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Premiere Issue

Premiere Issue

Celebrating the Launch of AE Power Systems Review Greetings from the President Progress in the Past Seven Years Highlights Technology Pros

pects New Technologies & Products
Development of 1,100kV 50kA Double-Break Gas Circuit Breaker 800kV 2,000MVA Transformer and 438Mvar Shunt Reactor Commercialization of Environmentally Friendly 72kV Dry-Air Insulated Switchgear Development of 24kV Cubicle-Type Dry-Air Insulated Switchgear Recent Technology Trend in Vacuum Circuit Breaker Preventive Maintenance Technology for Low-Viscosity Silicone-Fluid Immersed Transformers and Its Progress Development of Oil Palm Fatty Acid Ester Insulating Oil Trend of New Technologies for Insulation Diagnosis and Monitoring of Substation Equipment

TOPICS Affiliated Company in China Worldwide Network

Celebrating the Launch of AE Power Systems Review

Yasuji SEKINE
Professor Emeritus The University of Tokyo

I am pleased to hear the launch of the AE Power Systems Review. This good news indicates that AE Power Systems is about to enter the final stage in consolidating its foundations, seven years after its establishment in 2001. From what I hear, the business has been doing well since it was established, with export business performing well and with the company starting to earn profits from FY2006, which enables me to contemplate a brilliant future for AE Power Systems. Looking back over past years, the style of heavy electric machinery industry has changed, accompanied by a tendency toward deregulation of the electric power industry and drastic changes in the electricity business environment, which started in the latter half of the 1980s. While in Europe, ABB was established in 1988 through the merger of two giants, ASEA and BBC, in the United States, it was lamented that the United States no longer had major domestic companies that produced electrical power equipment, excluding gas turbines and other equipment. During the same period, Japan’s circumstance had been calm, supported by the increase in domestic demand, though Japan is said to have too many heavy electric machinery manufacturers compared to Europe or the United States. It is quite natural that after the turn of

the century, it also has followed the same trajectory as the international community. Internationally, the epicenter of activity in the electrical power industry has shifted from advanced countries to the three great regions of Africa, Asia and South America. Some thought that South America would be the first to become the driving force in the industry, but the tendency over these 20-30 years doubtlessly suggests that the center of its force has shifted to Asian countries such as China and India, though Brazil in recent years has shown rapid growth. Good evidence against this is the fact that, at the symposium of CIGRE (International Council on Large Electric Systems) held in Osaka, Japan in autumn last year, Dr. Ashok Manglick from Australia, who is the Chairman of AORC (AsiaOceania Regional Council), operated under the aegis of CIGRE, selected the topic of power grids in ASEAN countries for his keynote lecture, titled “ASEAN Power Grids.” The reason why Dr. Manglick selected the topic is not because symposium was held in Asia, but world’s attention is focused on Asia. In fact, it was AORC that held the first regional council of CIGRE. In his lecture, Dr. Manglick picked up the topic of the major international grid

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Celebrating the Launch of AE Power Systems Review

linking Southeast Asian countries and extensively discussed its related issues. Indeed, there is some debate concerning the problem of the term and the processes required for the project, but looking back on the history of electric power over the past 100 years or so, there is no doubt that this international grid will become reality at some point of this century. I would not be the only person to feel, while listening to Dr. Manglick, that this is where Japan comes in to make the project. We are in the era of globalization. The fact does not necessarily give us an advantage due to Japan being geographically close to Southeast Asian countries. However, it is certain that Japan has its own electrical power technological features that Europe and the United States do not have. This is evidenced by the following facts: Unlike China and India, Southeast Asian countries-the third greatest region in Asia following these two countries-consist of a large number of island nations and, in this sense, their geographical conditions are very close to those of Japan,and Japan’s electrical power technologies have been improved through natural disaster, such as earthquakes and typhoons, and the climactic conditions specific to this region, including monsoons. The coming years will be the very period of prosperity in the electrical power technologies that

have been developed over past decades by those who came before us. Furthermore, looking at ourselves 100 years ago as precedents and facing the present situation, it is not difficult to imagine that the innovative technology has come into actual use 100 years from now which seems to be impossible to conceive, There has been considerable debate in the world over what monozukuri (manufacturing) should consist of, but it is said that we are about to enter an era in which monozukuri (manufacturing) needs to be done based on research and marketing. Needless to say, technological development will provide a strong foundation for that. It is my sincerest hope that the AE Power Systems Review launched this time will serve as a great motive force for Japan AE Power Systems Corporation established in 2001-the first year of the new millennium-for the long struggle over the next 100 to 200 years.

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Greetings from the President

Takashi KANO
President and Director Japan AE Power Systems Corporation

worldwide to cover regions including the Middle East, Africa, North America, China and Southeast Asia, and I believe our mission is to contribute to the development of a social infrastructure from a global point of view. To manufacture products from the customer’s perspective and to provide finely textured services, efforts are also being made to ensure thorough quality control, that benefits from the synergy of the three companies’ technologies in research and development, integrating the experience, expertise and capabilities of the three long-established companies. This Premiere Issue of AE Power Systems Review presents some of the technological developments and achievements by our company in its efforts to contribute to society as an energy solutions company. The topics include the history of our company, trends with the latest technologies and some examples of environmentally-friendly products. Japan AE Power Systems Corporation is committed to continuing its efforts to create newly added value and to provide solutions to customers. Our company will aim at making further strides and will continue to strive for greater achievements without being satisfied with the status quo. I am pleased to present the Premiere Issue of AE Power Systems Review.

I would like to express my sincere gratitude to a range of people-including our valued customers, shareholders, our employees and their families, our business partners, and the people in local communities for the continuous and constant support they have provided us. Their support has allowed us to launch this AE Power Systems Review, which covers a series of technological topics of Japan AE Power Systems Corporation. Japan AE Power Systems Corporation is a company that supports the basis of the infrastructure for energy lifelines, and was established in July 2001, through a business collaboration among Hitachi Ltd., Fuji Electric Co., Ltd. and Meidensha Corporation in the transmission and distribution business field. As an “energy solutions company” that will play a key role in the next generation, we have set a basic policy of contributing to society in the area of electrical power infrastructure and is committed to working, looking ahead to the future. The business has now expanded

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Progress in the Past Seven Years

To become a Leading Company in the World

Seven years ago on July 1, 2001, Japan AE Power Systems Corporation was established through the merger of Hitachi Ltd., Fuji Electric Co., Ltd. and Meidensha Corporation, when transmission and distribution market has been exposed to increasingly harsh circumstances, and made a new start to become a leading company in the international arena. Here is seven years of the company’s history, in which AE Power Systems has made steady progress toward its goals by overcoming a number of challenges.

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Birth of AE Power Systems and the Consolidation of its Foundation
(2001 - 2002)
In the year 2000, the Japanese economy was in the midst of a chronic recession as a result of the collapse of bubble economy, and the manufacturers of heavy electric equipment were struggling in the harsh circumstances created by the restrictions on public spending and increasingly fierce global competition. There was also a growing awareness that too many heavy electric machinery manufacturers exist in Japan, despite the size of the domestic market. During this period, Hitachi Ltd., Fuji Electric Co., Ltd., and Meidensha Corporation had already established Japan Motor & Generator Co., Inc. through joint capital investment. The purpose of the company was to jointly develop high-voltage motors and small-medium size generators, and demonstrated that an integration of traditional technologies creates a great deal of power. In this context, Hitachi Ltd., Fuji Electric Co., Ltd. and Meidensha Corporation concluded to make a comprehensive business collaboration agreement regarding a partnership in the transmission and distribution field, and established a joint manufacturing company in January 2001 utilizing the experience that Hitachi Ltd. had accumulated from its achievements in large-capacity equipment in the transmission and distribution field, while Fuji Electric Co., Ltd. and Meidensha Corporation were competitive in medium-to-small capacity equipment. The new leading company integrated the advanced technologies that had been developed by the three companies. On July 1, 2001, Japan AE Power Systems Corporation (hereafter, “AE Power Systems”) was established with capital of six billion yen with its head office located at Chuo-ku, Tokyo. Initially, the focus was on consolidating the foundation of the new company and establishing its system, and started commissioned manufacturing. Then on October 1, 2002, through negotiations among the three companies, a business succession was

conducted with regard to products relating to transformers, high voltage switchgears, and medium voltage switchgears (VCB, VI). At that time, the capital was increased from six to twenty billion yen, and the Kokubu Administrative Division of Hitachi Ltd., the Chiba Administrative Division of Fuji Electric Co., Ltd., and the Numazu Administrative Division of Meidensha Corporation were officially inherited by the new company as its principal administrative divisions. The new company started to operate under a three-division system consisting of Transformer Business Division, High Voltage Switchgear Business Division and Medium Voltage Switchgear Business Division, and proceeded to eliminate and consolidate overlapping products and develop new products. In this way, Japan AE Power Systems embarked on a course to demonstrate the synergy of the business integration.

Progress in the Past Seven Years

Steps toward Independence
(2003 - 2005)
Japan AE Power Systems was launched in the manner described in the previous section. However, it was a trying start for AE Power Systems, even though, in 2003, the Japanese economy was finally emerging from its period of stagnation. To launch into full-scale independent business activities, AE Power Systems opened eight branches in Japan, and overseas, it established a series of representative offices, branches and sales subsidiaries in China (Shanghai), Singapore, the United States (Georgia), and the United Arab Emirates (Dubai). The domestic branches commenced independent business activities in February 2003, and AE Power Systems received its first order for two 275kV phase shifting transformers and two 300kV hybrid gas insulated switchgears from Tohoku Electric Power Co., Inc., as a major project for Japanese power utility company. AE Power Systems established in overseas a number of associated companies, namely, HVB

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Progress in the Past Seven Years

AE Power Systems, Ltd. in the United States, P.T. Japan AE Power Systems Indonesia (both of which are manufacturing and sales subsidiaries for gas circuit breakers (GCB) and gas insulated switchgears (GIS) and Shandong Luneng AE Power Systems Co., Ltd. (a joint venture company for manufacturing and selling GIS in China). AE Power Systems also established Shanghai AE Power Changcheng Switchgear Corporation in Shanghai, China in 2004 as a joint venture company for manufacturing and selling medium voltage, cubicle-type GIS. This is AE Power Systems’s first overseas joint venture that was established with a local partner, Tianshui Changcheng Switchgear Factory. While the different corporate cultures of the three companies were being gradually integrated, the first new recruits joined AE

Power Systems in April 2003, and each of them are now playing important roles. The major products developed during this period include the 66kV low-viscosity silicone liquid-immersed transformer, a product designed for disaster prevention that features superior flame resistance, as well as the 24kV dry-air insulated GIS,72kV dry-air insulated GIS and 72/84kV dry-air insulated dead tank type VCB, which are SF6 gas-free, environmentally-friendly units. Also the world’s first 120kV single-break dead-tank type VCB, the polymer insulator lightning arrester, which has superiority in earthquake protection, and 7.2kV VCB with magnetic actuator mechanism, which is among the smallest units in the industry, are the products developed by AE Power Systems. In October 2004, the High-Voltage, HighPower Testing Laboratory at Kokubu

Table 1. The History of Japan AE Power Systems Corporation and the Main Products Delivered/Developed

Manufacturing started (October 2001 –) The first new recruits Join the company (April 2003) AE Power Systems Business succession established (July 2001) (October 2002) [Capital: 20 billion yen] Shanghai AE established [Capital:6 billion yen] (January 2004) The comprehensive business Singapore Rep. Office and collaboration agreement signed Middle East Rep. Office Shanghai Rep. Office by Hitachi, Fuji, and Meidensha (January 2001) established (May 2003) established (April 2002)

800kV transformer and shunt reactor delivered to the Republic of South Africa 275kV phase-shifting transformer delivered to Tohoku Electric Power Low-viscosity silicone liquid-immersed transformers, sales starts

550kV GCB delivered to Egypt

72kV combined type vacuum switchgear (VFS) delivered 24kV dry-air insulated C-GIS, sales starts

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Administrative Division was accredited by the Japan Accreditation Board for Conformity Assessment (JAB) complying with ISO/IEC 17025, stipulating the requirements for competent testing and calibration laboratories. (Accreditation number: RTL01570).

Advance to Become a Global Company
(2006 - Present)
The Japanese economy has finally climbed out of the abyss of the lost decade, and the steady growth in corporate profits has led to continuous increases in private-sector capital investment, while public-sector capital investment remains subdued. The global market environment has also been rapidly improving due to the ascendancy of the BRICs countries, and in

particular, the remarkable growth of the Chinese economy. AE Power Systems has been implementing G-10 movement, a medium-term business plan leading up to the fiscal year 2010. AE Power Systems has, supported by the economic boom, and its orders and sales have been steadily increasing, as targeted in the medium-term business plan. In 2006, the amount of orders received exceeded 100 billion yen for the first time, and the export ratio reached 43%. In 2007, the amount of orders received continued to be favorable, exceeding 100 billion yen for two consecutive years and attaining new record highs, while the export ratio increased to 50%. Since its establishment, AE Power Systems has been setting up overseas manufacturing bases in an effort to become a global company, and in April 2007, established the AE Power (Suzhou)

Progress in the Past Seven Years

AE Asia established (September 2004) AE-HVB (USA) took over from Hitachi. (March 2005)

AE Indonesia took over from Hitachi. (August 2005) AE America integrated into AE-HVB (July 2005)

Shandong AE’s new 550kV building completed (November 2006) Suzhou AE established (April 2007)

AE America established (April 2004)

Semi-turnkey construction of 220/66/21kV substation in Bahrain Full-turnkey construction of 110/34.5kV substation in Saudi Arabia Full-turnkey construction of 380/110/13.8kV substation in Saudi Arabia 525kV 545MVA transformer delivered to Tokyo Electric Power 800kV transformer and shunt reactor delivered to the Republic of South Africa

220kV 250MVA site assembly transformer delivered to Kyushu Electric Power Hybrid cast resin transformers with noise reducers, sales starts 275kV 400MVA site assembly transformer delivered to Hokuriku Electric Power

First order for 550kV GCS received by Shandong AE First order for 550kV GIS received by Shandong AE 800kV GCB delivered to the United States 550kV GIS (with polymer bushing) 72kV gas-free GIS sales starts introduced to system at 550kV GIS delivered to Tohoku Electric Power Hokuriku Electric Power 266kV polymer insulator lightning arrester 345/138kV GIS delivered to the United States delivered to Tohoku Electric Power 72kV dry-air insulated VCB delivered to The Chugoku Electric Power 72kV dry-air insulated VCB delivered to the United States

General-purpose 7.2kV VCB with magnetic actuator mechanism, sales starts

120kV VCB delivered to The Chugoku Electric Power 7.2kV VCB with magnetic actuator mechanism, for power utilities, sales starts

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Progress in the Past Seven Years

EHV Switchgear Corporation in Suzhou, China, as a joint venture engaged in engineering and manufacturing of units for GIS and GCB. As Figure 1 shows, AE Power Systems has now established a global quadrilateral framework consisting of the Middle East, China, Southeast Asia and the United States. Notable orders received in the export businesses to include: 1) a continuous major contract for 800kV transformers and shunt reactors for the Republic of South Africa; 2) continuous major orders for transformers and GIS for Dubai and Bahrain in the Middle East and; 3) 800kV deadtank type GCB for the United States. AE Power Systems has also signed a technical collaboration agreement for 1,100kV GIS with New Northeast (Shengyang) High Voltage Switchgear Co., Ltd. in China-a company that had been collaborating with Hitachi Ltd. before AE Power Systems was established-and is conducting a trial transmission project for UHV (1,100kV) in China using equipment that was manufactured jointly with this company. For domestic power utility companies, the main products delivered by AE Power Systems include 550kV GIS for the Kamikita Substation

of Tohoku Electric Power Co., Inc., 220kV site assembly transformer for the Kami Shiiba Power Station of Kyushu Electric Power Co., Inc., and 275kV site assembly transformer for the Nakanoto Substation of Hokuriku Electric Power Company. At the annual shareholders’ meeting in June 2007, Mr. Takashi Kano took over as President from Mr. Masakazu Mori, who had been President and Director since the establishment of AE Power Systems. AE Power Systems has been making a concerted and united effort to be a company that meets the trust of its customers under the slogan of “Leap Forward to Become a Leading Global Company”.

<1> VCB: Vacuum circuit breaker <2> VI: Vacuum interrupter <3> GCB: Gas circuit breaker <4> GIS: Gas insulated switchgear <5> BRICs: Brazil, Russia, India and China, where major economic growth in the 21st century is anticipated.

Shandong Luneng AE Power Systems Co., Ltd.

GIS

Shanghai AE Power Changcheng Switchgear Corporation C-GIS, VCB AE Power (Suzhou) EHV Switchgear Corporation Shanghai Fuji Electric Transformer Co., Ltd. Shanghai Zonfa E Power EHV Equipment Co., Ltd. GIS, GCB, Engineering Cast resin transformer GIS, GCB

HVB AE Power Systems, Inc. Sales, Engineering, GCB, VCB Chang Shing Electric Co., Ltd. Transformers

AE Power Metal Engineering Sdn. Bhd. Transformer accessories

Meiden Electric (Thailand) Ltd.

Switchgears

Japan AE Power Systems Asia Pte. Ltd. Sales, Engineering Meiden Singapore Pte. Ltd. Tr., SWGR, C-GIS, VCB

P.T. Japan AE Power Systems Indonesia

GIS, GCB

Figure 1. AE Power Systems’s Overseas Bases

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View of a substation

The network system of the north area of Tohoku Electric Power Co., Inc. is a 500kV main transmission system, which will be newly constructed related with the recent development plan for building a nuclear power plant in the Shimokita district of Aomori Prefecture in Japan. The system is to deliver the generated power and the local region secures a stable power supply. AE Power Systems has supplied the following equipment to this new power network system. (1) 13 bays of 550kV gas insulated switchgear (2) 2 bays of 550kV hybrid gas insulated switchgear (3) 3 bays of 300kV gas insulated switchgear (4) 3 units of three-phase auto-transformer with OLTC (5) 16 bays of gas insulated switchgear for tertiary circuit of main transformer Considering the importance of the network system of the north area, several design concepts have been carefully considered under the special conditions of

the site location and transportation restrictions, such as total economical advantages, easy maintenance and ultimate system reliability. Features of the equipment are as follows. 1. 550kV Gas Insulated Switchgears (1) A verification test of the interrupting performance for long line faults (LLFs) has been carried out for this unit. The test verified that the unit provides stable, long-distance transmission for a large capacity of electricity, which had been a technical challenge. (2) An optimal layout consisting of the best combination of components, featuring the use of a horizontal type (L-shaped) single-break GCB (for transmission lines and transformer lines) that offers strong anti-seismic protection and economic efficiency, and a vertical type singlebreak GCB used for the bus tie circuit. (3) The long gas insulated bus (GIB) comes with the optimum arrangement of bellows that absorb the displacement and the thermal expansion and

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500kV Substation Equipment Delivered to the Main Network System of the North Area of Tohoku Electric Power Co., Inc.

Highlights

Verification test of 550kV GIS

contraction caused by an earthquake. (4) Application of compact bushing which features superior anti-seismic protection and economic efficiency (5) Use of a upgraded lightning arrester (LA) with extra-high voltage elements. 2. Three-Phase Auto Transformer with OLTC (1) The site assembling method of the main tank has been applied considering the substations site requirements, transport conditions and installation space. (2) Improved seismic protection enabled by lowering the position of the connecting part of the primary and secondary sides into GIS. (3) A fire fighting system using nitrogen gas, which features superior versatility, stable supply and high economic efficiency. (4) The switchgears of the tertiary circuit are directly connected to the transformer, which permits streamlining of the peripheral devices arranged in the neighborhood.

These and other technologies of AE Power Systems for electrical power transformation are combined and reflected in the equipment.

550kV GIS at site

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800kV Dead-Tank Type GCB for the United States

800kV GCB

AE Power Systems has completed the 800kV deadtank type GCB for major power utility company in the United States, and shipped the first unit in January 2008. It was the first order received for a 800kV-class GCB to the United States. Since the widespread Northeast Blackout of 2003, power utilities in the United States have been reinforcing the power system networks. One of the major power utility companies, has been promoting an interstate transmission project. This project uses 800kV power transmission line spanning approximately 890km from the state of West Virginia to New Jersey. The widely used, conventional 800kV-class GCB drives four breaker units to interrupt the current in the event of an failure. But the new GCB shipped to the United States this time is capable of interrupting the current by driving only two breaker units. This has permitted the new GCB to achieve smaller size, higher reliability and reduced cost. In conducting the verification tests of the new GCB, the required conditions were more severe than those stipulated by American Standards. However, the GCB successfully passed all items in the witness tests that were conducted multiple times. AE Power Systems’s technologies were given high marks, leading to the order for the 800kV dead-tank type GCB. The new 800kV GCB consists of two latest-model 420kV GCB units that AE Power Systems had delivered to the utility companies. The two units are

connected in series, and sharing the interrupting part, the operating mechanism part, and many of the mechanical linkage parts. This scheme has resulted in reduced cost, greater reliability, and shorter development period. To downsize the unit, the distribution of electrical field strength has been optimized through three-dimensional electrical field strength analysis. Additionally, the new GCB features an operating characteristic and the structure of the interrupting part that ensure stable current interrupting performance under various conditions, ranging from small to large current. AE Power Systems achieved them by making full use of its analysis technologies, such as operating analysis and hot gas flowing analysis. In China, a project has been underway to connect the coastal areas, where there is heavy consumption of electrical power , and the major power supplies in inland areas. The areas will be connected with 800kV and 1,100kVclass power transmission lines. Also, improvement of 800kV-class transmission network is ongoing in the Republic of South Africa, while the construction of a 1,200kV-class transmission network is being considered in India. In this way, ultra highvoltage power transmission technologies are attracting greater levels of attention around the world and demand for such technologies is growing on a global scale. The completion of the new 800kV GCB will contribute to AE Power Systems’s business expansion in those new markets.

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220/66kV Substation Project at Kingdom of Bahrain
Highlights

150MVA Transformer

220kV GIS

The Kingdom of Bahrain is an island country with a population of about 760,000. The country consists of 33 large and small islands located in the Persian Gulf to the east of the Arabian Peninsula. This country has been undergoing continuous substantial development. In addition to crude oil exports, the country has been engaged in petroleum refinery and aluminum smelting as its major industries since an early period. Bahrain is also striving to become the financial center of the Middle East. This development has allowed a population growth of about 2% per year, spurring large-scale projects for city planning and enhancements to electrical power infrastructure. To play a major role in the development of Bahrain, AE Power Systems has set up a Bahrain project office in 2002, and has been engaged in the delivery and installation of equipment for a large number of 220kV and 66kV substations, which constitute the primary network systems of the country. Electricity & Water Authority (EWA), which has a dominant role in most of the power generation and all of the power transmission and distribution in the country, has been making ongoing orders for 220kV and 66kV substations as semi-turnkey projects. AE Power Systems has delivered and installed GIS and transformers at fifteen 220kV substations and four 66kV substations (work is ongoing at additional 12 substations) for the EWA. The market share of AE Power Systems in the country is very high at

approximately 50%, and its products are widely spread in the 220kV network systems in Bahrain. AE Power Systems has also delivered a large number of GIS and transformers to aluminium smelter, one of the most important industry in the country, as well as for other development projects by the private sector. Because of its highly stable operation, the reliability of AE Power Systems’s equipment has become highly regarded in the country. In this way, a large number of new substations has been constructed or expanded every year since 2002, and AE Power Systems has been contributing to the client’s scheduled operation plans. This is attributed greatly to the work of its local project office. The Bahrain Project Office has been coordinating all processes for the projects, from planning stage to installation tests. This office comprises of staff that come from various countries, including Japan, Bahrain, Europe and Asia, and ensures smooth implementation of the projects through close collaboration with client, technical consulting firms and local subcontractors.

66kV Substation building

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Successive Shipments of Large Transformers
250MVA Site assembly transformer for the Kami Shiiba Power Station of Kyushu Electric Power Co., Inc.

In 2007, AE Power Systems consecutively shipped a number of large transformers both for Japan and overseas countries. In Japan: 1) AE Power Systems shipped a 500kV 1,300MVA main transformer to the Kamikita Substation of Tohoku Electric Power Co., Inc., and started installation. Constituting part of Tohoku Electric Power’s project for improving its 550kV primary network system, the shipment and installation of the equipment is one of the most important projects that the company has undertaken. The installation work will be completed in 2009.; 2) AE Power Systems shipped a 220kV 250MVA main transformer to the Kami Shiiba Power Station of Kyushu Electric Power Co., Inc., and a 275kV 400MVA main transformer to the Nakanoto substation of Hokuriku Electric Power Company. Both of these units are site-assembly transformers. The site-assembly transformer was developed for regions and sites where the space for installation is limited or where transportation is made difficult by bridges, tunnels or road conditions. The latest siteassembly transformer delivered this time incorporates new technologies that allow the installation to be performed in a more confined space and more quickly than with previous units.; 3) AE Power Systems shipped a number of step-up transformers to thermal and nuclear power plants, including the 275kV 545MVA step-up transformer for a thermal power plant of Tokyo Electric Power Company, Inc. and 230kV 490MVA step-up transformers for nuclear power plants in Japan. Overseas: 1) AE Power shipped 110/34.5kV 120MVA, 150MVA main transformers and others to

primary substations as offsite utilities for petrochemical plant in the Kingdom of Saudi Arabia. It was a project requiring an exceptionally short delivery time, but it was completed in time for the contracted delivery date. 2) Many shipments were also made to Middle East countries, where rapid infrastructure development has been in progress. AE Power Systems shipped total of 56 units, including 132kV 50MVA transformers and 132kV 30Mvar shunt reactors, for Dubai Electricity and Water Authority (DEWA). 3) The electrical power infrastructure has been actively developed in the Republic of South Africa, which will host the FIFA World Cup in 2010. AE Power Systems shipped three 765/ 3kV, 2,000/3MVA single-phase transformers (one bank) and six 800/ 3kV, 438/3Mvar single-phase shunt reactors (two banks) for the 800kV Primary Substations of the state-owned utility, ESKOM. AE Power Systems is scheduled to ship many more transformers and shunt reactors for ESKOM until 2011; 4) AE Power Systems also shipped two 220kV 250MVA transformers to the Republic of Azerbaijan, which is a former Soviet satellite state. It was the first shipment by AE Power Systems to the country. In addition to the above, AE Power Systems shipped a large number of transformers in 2007, which was a boom year for transformers for the company.

Transformer tank being hauled to petrochemical plant in Saudi Arabia

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40.5kV C-GIS Delivered to Qingzang Railway in China
Highlights

Tuotuohe Station located at 4,547m above sea level

The Qingzang Railway runs between Golmud (altitude: 2,828m) in Chinghai Province, a mountainous area in the western China, and Lhasa (altitude: 3,641m) in the Tibet Autonomous Region. The total length of this railway is 1,140km, and it has the highest elevation in the history of railways with a summit at 5,072m. For this reason it is also called Tianlu (Road to Heaven). For the Qingzang Railway, AE Power Systems delivered in January 2006 a total of 11 sets (33 panels) of 40.5kV, 1,250A, and 31.5kA cubicle-type GIS (C-GIS) , which were developed as models that

suit the Chinese market. It was the first order received by Shanghai AE Power Changcheng Swichgear Corporation (Shanghai AE), a new jointly owned company of AE Power Systems in China. The construction of Qingzang Railway is a national project in China, and has attracted attention not only in China but also around the world. First train ran on July 1, 2006, and became an international news topic. Of the 1,140km railway, 546km passes through permafrost, and 958km passes through high-altitude areas in excess of 4,000m above sea level. At 4,000m, atmospheric pressure drops to about two-

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thirds that at ground level. Specific measures for highlands, countermeasures against low temperature in the permafrost, long-distance transport, and other issues made it exceptionally difficult to perform the installation and testing in these areas. However, AE Power Systems led by Shanghai AE collaborated with its local partner, Tianshui Changcheng Switchgear Factory, and completed the delivery without problem before the scheduled deadline, thereby contributing to the start of the railway’s operation. Shanghai AE’s technical capabilities and management of the delivery date were highly regarded, and an additional order for 60 units was received in May 2006. Installation of the 60 units was

completed without any problem. There is a plan to construct the branch lines and further orders for Shanghai AE can be expected thanks to its highly regarded achievements concerning the project above. Shanghai AE is determined to conduct its business through cooperation with related parties, with the aim of receiving more orders from the country.

40.5kV C-GIS

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IEC Type Test Certificate Granted for the Cast Resin Transformer

Highlights

Certificate

A notable feature of a cast resin transformer is its flame resistance, which is due to the epoxy resin that covers the surface of the winding. This transformer is widely used for high-rise buildings, plants, public facilities and other applications, as a transmission and distribution facility with superior disaster prevention properties. In 2004, the IEC 60076-11 (dry-type transformer) was revised. The major purpose of the revision was the addition of three new special test items: climatic test (crack resistance test), environmental test (humidity resistance test), and fire behavior test (flame resistance test). To engage in these type tests, AE Power Systems produced a prototype for a threephase 1,000kVA cast resin transformer. At CESI, the official testing institute in Italy, AE Power Systems passed all the special items of IEC type tests, recording a first for a Japanese manufacturer, and was granted the IEC type test certificate. In the newly

added fire behavior test (flame resistance test), a cast resin winding is put into a test container and ethyl alcohol is ignited, thereby confirming that the temperature increase at the measurement site in the chimney is within the specified range. In other words, this test simulates a fire to assess the flame resistance of the cast resin winding. AE Power Systems’s cast resin transformer passed this test with a figure that is far below the criteria. The unit also passed the climatic test (crack resistance test) and environmental test (humidity resistance test), which provided renewed proof of its superior resistance against flames, cracking and humidity. This achievement was made possible by joint research with Fuji Electric Systems Co., Ltd. The IEC type test certificate provides evidence of the high performance, high quality and high reliability of AE Power Systems’s cast resin transformers.

Fire behavior test (unit on fire)

Fire behavior test (fire has been extinguished after the test)

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Technology Prospects
Japanese electrical industry passed a turning point when Japan’s bubble economy depressed in 1990. In terms of technologies, two large-scale projects, development of UHV-AC 1,100kV and HVDC±500kV equipment, were promoted, aggregating all the technologies of the 20th century in this field. And in the 21st century, Japan AE Power Systems Corporation (hereafter AE Power Systems) was established in the period that the mergers and acquisitions became active in various business fields. The development of technologies for a “safe and secure society” and for “the global society” is required in the area of transmission and distribution, as well. AE Power Systems has been engaged in developing products and technologies that will meet such requirements by combining advanced technologies of the three long-established companies. AE Power Systems is committed to continue its efforts for their early realization.

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1. Preface
The electrical industry passed through a turning point when the Japan’s bubble economy depressed 1990. In terms of technologies for electrical power transmission and distribution , two large-scale projects, development of UHV-AC 1,100kV and HVDC±500kV equipment were promoted, aggregating all the technologies of the 20th century developed in this field. On the demand side, the Japanese domestic market faced a downturn in the demand for electrical power due to the emphasis in conserving energy and achieving safety. It was also the beginning of a new era that spread more dispersed power sources and accelerating the electric utility deregulation. Also, the price collapse that hit both the domestic and overseas markets started to affect the electrical industry as well. Under these circumstances, companies in the industry were forced to take measures to win their survival. Internally, they took measures such as cost-reduction and initiatives that included early retirement programs. Externally, they embarked on overseas operations or became involved in mergers and acquisitions with other companies in the same field.(1)

It was in this context that AE Power Systems was established in 2001 by amalgamating the transmission and distribution divisions of Hitachi Ltd., Fuji Electric Co. Ltd., and Meidensha Corporation.

2.Circumstances Surrounding the Transmission and Distribution Equipment and Measures Taken by AE Power Systems
Technology Prospects

Figure 1(1) shows the circumstances that have been surrounding transmission and distribution equipment since the end of the 20th century. The circumstances have changed a great deal due to the policies for energy conservation etc., market trends toward deregulation, globalization and liberalization, and the global community with its increasing emphasis on perceptions of the public and environmental friendliness. Figure 2 shows the major trends of technologies for substation equipment during the 20th and 21st centuries. The technological development in the initial period was focused on a high level of functionality, high performance and economic

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efficiency, which involved working to achieve higher capacity with smaller equipment size amongst other attributes. The demand for a high level of reliability, environmental friendliness and safety increased further with the arrival of the information society in the latter half of the 20th century. In the 21st century, achieving a safe, secure society as well as a global society has been the technical issue. The specific technical matters to be promoted are the listed in Figure 2. AE Power Systems has been devoting itself to the development of new technologies geared for the respective technical goals, based on the superior technologies inherited from each of the three companies and by utilizing the synergies of those technologies. AE Power Systems is committed to continue its efforts for their early realization.

following sections describe the specific measures that have been taken in response to these situations. 3.1 Evolution of Vacuum Technologies Vacuum technologies hold the key to environmental protection. Especially in terms of the current breaking technology there is the prospect of introducing solid state circuit breakers that apply semiconductors or superconductivity. However, it is expected that it will take some more time to achieve loss reduction and to develop superconductivity technology that functions at normal temperatures. Consequently, there are rising expectations for achieving higher voltage and larger capacity for vacuum interruption technologies that do not have an interruption medium.

3.The Prospects for Ecological Technologies in Achieving a Safe and Secure Society
Countermeasures against global warming constitute an urgent issue for environmental protection. This has also called for demands for safety measures to provide protection against earthquakes and fires and for the prevalence of energy-saving devices. The

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Technology Prospects

Figure 3 shows a vacuum interrupter (VI) and an electrode (vertical magnetic field electrode system) which are the most vital device of a vacuum circuit breaker. Improvements in VI have also been enabled by improvements in the electrode which has allowed us to develop single-break units of up to 145kV, so further development is expected. 3.2 Development of New Insulation Materials New insulation materials for substation equipment include those for environmental protections and for disaster prevention. (1) For Transformers New insulation materials for transformers are intended for reducing damage to the environment in the event that the insulation medium spills out and for ensuring flame resistance to prevent fires (it is difficult to make liquid inflammable). Transformers using silicon liquid or vegetable oil (Figure 4(1): palm oil) whose firing points are 250 or more while that of mineral oil is 145 are being developed at the moment, and are expected to become popular in the future.

in Kyoto, Japan in 1997. Materials to act as substitutes to SF6 gas have been studied for a long time, but the issue remains a great challenge for the industry because each alternative has its own rawbacks and advantages. In recent years after COP3, the use of CO2, N2, dry air, CF3I gases and the aforementioned vacuum technologies have been studied, and the combination of dry-air insulation and a vacuum circuit breaker has actually been used for equipment of a relatively lowvoltage class. However, many issues have yet to be resolved before it can be applied to high-voltage, high-capacity equipment. Therefore, the results of further research and development is awaited, including those for mixed gases. (3) Common Technologies One of the technologies that is common to all substation equipment is composite insulation technology. As a means of applying this technology, the use of composite insulator (a fiber-reinforced plastic tube whose outer surface comes equipped with silicone rubber that is highly water repellent) has increased as an alternative to porcelain insulators. Verification tests for composite insulators, including those in Figure 5, have been conducted, allowing them to be actually used for bushing insulators for 500kVclass equipment. Recently, its use has further increased to trial use for UHV level. The composite insulator is light-weighted and prevents splashing. Therefore, it is hoped that this insulator will be applied to high-voltage, highcapacity equipment, ensuring long-term reliability

Technology Prospects

(2) For Switchgears For switchgears, insulation materials using SF6 gas, which features outstanding insulation and interruption performance, have been developed and widely used since the beginning of the 1970s. However, the Global Warming Potential (GWP) of SF6 gas is so high at 23,900 that it was designated a greenhouse gas at the 3rd Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change(COP3) that was held

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even in a country such as Japan that experiences frequent earthquakes. 3.3 Top Runner Program One of the social initiatives to conserve energy is the Top Runner Program. For oil-immersed transformers for high-voltage transmission and distribution, the program was established in April 2006 (with the program for cast resin transformers being established in April 2007). This is aimed at significantly reducing power loss (by approx. 40% compared with the conventional JIS standard) which will contribute to the reduction of CO2. AE Power Systems released a series of cast resin transformers ahead of other companies, achieving smaller size, lighter weight, reduced noise and even greater reliability using vacuum-cast winding.

4.Prospects for High-Performance and Highly Reliable Technologies for the Global Society
Technologies for substation equipment that have been developed so far . including those for up to UHV (1,100kV) transformers and circuit breakers have been widely applied in Japan as a matter of course. However, it is also important to introduce these technologies to the BRICs, where economical development is booming. AE Power Systems is pioneering its realization with high-performance, highly reliable products. 4.1 Development of Products of 500kV and above There has been growing demand for highperformance, large-capacity equipment as transmission and distribution technology to support the globalized information society. Such equipment is needed, for example, to reinforce the 500kV network systems in Japan, to stabilize and improve the network systems in the United States, and to provide assistance to developing countries. (1) Reinforcement of network systems for 500kV and above

The 500kV equipment, with the highest voltage in Japan, now needs to have its capacity reinforced or to be replaced to meet the growing demand for electrical power and to ensure higher reliability. AE Power Systems will respond to the situation by recommending equipment with higher reliability including, for example, superior anti-seismic characteristics. (2) Development of 800 1,000kV equipment to accommodate UHV equipment The application of UHV transmission, although its introduction has been postponed in Japan, has been underway overseas. In recent years, the improvements to 800kV systems in the United States and South Africa and construction for the experimental transmission project of 1,100kV power in China have reached their most climax. AE Power Systems has been developing the equipment for these projects by applying its state-of-the-art technologies to optimize the design. It is thought that further globalization of AE Power Systems’s activities, including its advance into India, will be necessary over the next few years. Figure 6 shows the development test of circuit breakers for the above projects.

(3) Measures to Accommodate Various Installation Environments Installation environments and transport conditions for substation equipment have also been changing. In Japan, site assembly technologies for transformers have been developed to cope with transport constraints. The demand for replacing transformers is

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expected to increase in the future, and these technologies will be further improved. Concerning switchgears, a space-saving GIS has been the most prevalent form of equipment in Japan. But this has not necessarily been the case in overseas, where AIS system (porcelain-type air insulated equipment) and hybrid GIS (with air insulation bus system) are used in many cases. Development efforts need to be continued to meet these overseas demands as well. 4.2 Improvement of Reliability and Economic Efficiency Japan’s technologies for ensuring the reliability of electrical power systems have high international standing. Reliability to prevent abnormal voltages caused by lightning or accidents, as well as the economic efficiency of the facilities, have been experiencing ongoing progress in the form of “Insulation co-ordination”. The underlying technology is that used in high-performance lightning arresters that were originated in Japan. Feature upgrades and development of associated equipment have been achieved for units up to the UHV class. The proportion of aged equipment that have supported growth of Japanese economy for 30 to more than 50 years will increase in the coming years. Therefore, it is also an important task to maintain the high reliability of the electrical power system preventing problems incorporating these aged devices and by ensuring their smooth replacement. (1) Insulation Reduction The mainstream technology used around the world for the lightning arrester is the zinc-oxide surge arrester, which is a Japanese origin. Improved reliability through the superior performance of the arrester and the downsizing of units by reducing the insulation has been conducted for units up to the UHV class. In recent years, further downsizing of the equipment has become possible by improving the arrester element.
Reference

(2) Improvement in Diagnostic Technologies To maintain superior reliability, it is essential to develop technologies to prevent abnormalities in the equipment in advance, and the development of such technologies has been continually underway. In the early stage development efforts were focused to detect the abnormal condition at high sensitivity. More recently, however, the development of diagnostic technologies is mainly focused to improve risk assessment and guidance capabilities to provide users with appropriate instructions concerning how to respond when abnormalities are detected. (3) Increased Need for Handling Aged Equipment The demand for transformers and circuit breakers, which are the main substation equipment, had been growing through the high-growth period until the mid 1990s. The growth in demand has been slowing down since that time, but the proportion of aged equipment, which have been used for 30 to 50 years, has increased and has become a major issue for both users and manufacturers. In terms of the technologies, it is important to develop products and renewal technologies that meet the requirements for renewal and to develop greater precision in the diagnosis of aging equipment and the insulation life of the equipment. Therefore, it seems necessary to tackle these issues through cooperation and joint research with users and by making full use of the accumulated technologies.

Technology Prospects

5. Postscript
Judging from the recent social environment, transmission and distribution technologies in the 21st century will be primarily directed toward ecological technologies for a safe and secure society and technologies to provide high levels of performance and reliability for the global society. AE Power Systems is committed to continue its efforts to achieve these goals as soon as possible by combining the advanced technologies of the three long-established companies.

(1) Yamagiwa, T. Shinjidai no Denki Sangyo no Yakuwari. The 2007 Annual Meeting Record of I.E.E. Japan, Chapter 7. Energy Conversion and Transportation, 2007, p.7-S11 (18-21). (in Japanese)

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New Technologies & Products

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Development of 1,100kV 50kA Double-Break Gas Circuit Breaker
Rei HEMMI Michiru ONODERA Kunio HIRASAWA Hirohiko YATSUZUKA

New Technologies & Products

[ Figure 1 ] Dielectric test configuration of 1,100kV GCB

AE Power Systems has developed a new 1,100kV, 50kA double-break SF6 gas circuit breaker (GCB) without resistor interrupter used in gas insulated switchgears (GIS). Type tests for items, such as dielectric, breaking and mechanical performance, have been carried out and successfully completed. The new GCB will be applied to GIS for China and will be in service at the end of 2008.

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New Technologies & Products

Introduction
In recent years, there have been projects, such as those in China, involving ultra high voltage (UHV) transmission exceeding 800kV. AE Power Systems has developed a new 1,100kV, 50kA double-break SF6 gas circuit breaker (GCB) without the resistor interrupter used in gas insulated switchgears (GIS). The development of UHV-GCB is based on the technology used in 550kV single-break GCB, and the new GCB has two interrupter units, without opening resistor units, located in series in the enclosure.

Ratings and Features of 1,100kV GCB
Table 1 indicates the ratings of the 1,100kV GCB. The appearance of the new GCB is shown in Figure 1. In Table 1, two types of UHV-GCB with different interrupting method are compared as well. The new GCB is smaller in volume and more lightweight than the other. Although the double-break configuration is applied to both types of UHV-GCB, the newly developed GCB without an opening resistor clearly has a more severe breaking duty than the GCB with opening resistor and its auxiliary interrupter. However, the high performance of the interrupter

[ Table 1 ] Ratings, specifications and features of 1,100kV GCB

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used in the 550kV, 63kA single-break GCB enables the new UHV-GCB to have enough breaking capability. An oil-immersed hydraulic operating mechanism has been selected and incorporated in the new 1,100kV GCB. The hydraulic mechanism is adjusted to have the same opening and closing travel characteristics of moving contacts of the 1,100kV GCB as those of the 550kV single-break GCB. The height at the center of the newly developed GCB is the same as that of the conventional GCB with opening resistor units, enabling the new 1,100kV GCB to be installed in a GIS equipped with the conventional GCB.

3-2 Breaking Performance The breaking performance of the interrupting unit was investigated, and the interrupter of the 550kV, 63kA single-break GCB was reviewed. Figure 2 is a typical example of the numerical analysis of the breaking performance. It shows time variation of hot gas distribution between the conductor and enclosure after the current interruption. High power tests to investigate the various interrupting performances of the GCB have been carried out and the new GCB was proven to have good interrupting capability. Figure 3 indicates a

Investigation and Development Test
Investigations into the various types of performance and the development tests on the 1,100kV GCB have been carried out.
(a) 10ms after current interruption
New Technologies & Products

3-1 Dielectric Performance The dielectric performance was confirmed through 2D and 3D electric field simulation for phase-to-earth and across the interrupter. Dielectric tests of the power frequency, the lightning impulse and the switching impulse for the specifications shown in Table 1 were carried out and the UHV-GCB successfully withstood the related voltages for phase-to-earth and across the circuit breaker. Partial discharge (PD) measurement was also performed. The PD level was proven to be very low, at less than 3pC (noise level) at the applied voltage of 1.2E.

(b) 20ms after current interruption

(c) 40ms after current interruption

[ Figure 2 ]
Time variation in distribution of hot gas temperature after interruption.
(Duty T100a, interrupting current = 50kA, arcing time = 1.5cycles)

[ Figure 3 ] Typical waveforms of breaking test (T100s) (1)

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New Technologies & Products

typical example of the waveforms in the breaking test for the T100s. Type tests, which comply with the relevant IEC and Chinese standards, were also carried out at an independent neutral testing laboratory. The tests were successfully completed and the breaking performance of the interrupter was verified(1). Figure 4 shows the breaking test configuration performed at the Xi’an High Voltage Apparatus Research Institute (XIHARI) in China. The main items of the breaking tests, including the full-pole test, were carried out at this laboratory. 3-3 Other Types of Performance Some other tests were conducted on the 1,100kV GCB, such as temperature rise, operation characteristics and mechanical endurance, and the GCB was proven to have good performance.

Application to Product
Two circuit breakers will be installed as part of the GIS in Nanyang switching station, which is one of the pilot plants in the 1,100kV transmission project in China. The switching station is planned to be in service in December, 2008.

Conclusion
A new 1,100kV 50kA double-break GCB without an opening resistor has been developed. The type tests have been successfully completed and it was confirmed that the GCB has the performance needed for the various specified duties.

References
(1) R. Hemmi, et al. Development of 1,100kV 50kA Double-Break Dead Tank Type Gas Circuit Breaker. The 2008 Annual Meeting Record I.E.E. Japan, Vol. 6, 2008, p.339.

Authors

Rei HEMMI
Design Department, High Voltage Switchgear Business Division Doctor of Engineering A member of the Institute of Electrical Engineers of Japan

Michiru ONODERA
Design Department, High Voltage Switchgear Business Division

[ Figure 4 ]
Breaking test configuration of new 1,100kV GCB
(The main items of breaking tests were carried out at XIHARI, China.)

Kunio HIRASAWA
High Voltage Switchgear Business Division A member of IEEE, CIGRE, and the Institute of Electrical Engineers of Japan

Hirohiko YATSUZUKA
President P.T. Japan AE Power Systems Indonesia A member of the Institute of Electrical Engineers of Japan and the Japan Society of Mechanical Engineers

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800kV 2,000MVA Transformer and 438Mvar Shunt Reactor
Michinobu FUKUI Keizo KAWANISHI

New Technologies & Products

[ Figure 1 ] 800kV Transformer

[ Figure 2 ] 800kV Shunt Reactor

AE Power Systems has recently completed the manufacturing of single-phase 765/ 3kV, 2,000/3MVA auto-transformers and 800/ 3kV, 438/3Mvar shunt reactors for inter-grid 765kV substation , whose voltages are among the highest, and capacities are among the largest in the world. The points to be considered in designing a transformer include 1) countermeasures for leakage flux, 2) enhancing the optimum insulation, and 3) measures for mechanical strength, all of which are to be applied as appropriate for high-voltage, large-capacity equipment. The points to be considered in designing a shunt reactor include 1) countermeasures for mechanical oscillation and noise, 2) countermeasures for local heating of leakage flux and fringing flux, amongst others. AE Power Systems has overcome a number of design issues and manufactured the units under strict quality control. Consequently, AE Power Systems has secured adequate quality and accumulated a great deal of design and production technologies for the future.

Introduction
In 2004, AE Power Systems has completed manufacturing of six single-phase 765/ 3kV, 2,000/3MVA auto-transformers and seven 800/ 3kV, 438/3Mvar shunt reactors, whose voltages are among the highest, and capacities are among the largest in

the world. The units are used for inter-grid 765kV substation. Thereafter, in 2007, AE Power Systems received orders for seven auto transformers and 22 shunt reactors with the same respective specifications as those of the units mentioned above, and these units are now being manufactured. The transformers and reactors are made aiming at achieving further

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New Technologies & Products

reliability, based on the experience in producing single-phase 765/ 3kV, 2,000/3MVA autotransformers and single-phase 800/ 3kV, 438/3Mvar shunt reactors in 1985, giving careful consideration to the design and production processes. The following sections outline this transformer and shunt reactor.

Specifications and External Configuration
The specifications of the transformer and reactor are shown in Table 1 and Table 2. The 2,000MVA transformer bank capacity and 438Mvar reactor bank capacity are both among the largest in the world. The insulation levels are 1,950kV lightning impulse test, 800/693kV long duration induced AC voltage test, and 1,425kV switching impulse test. The external view of the transformer is shown in Figure 1, and the shunt reactor is shown in Figure 2.
[ Table 1 ] Specifications of the transformer

return path legs. The yoke and return path leg come with an oval cross-section, which equalizes the flux flows and the distribution of the clamping force. This results in favorable properties and improved oscillation and noise characteristics. Within the crosssection of the cores, three cooling ducts are installed in parallel with the lamination layer, and one installed vertically, which permits superior cooling characteristics. 3-2 Winding The main leg consists of two legs, in which exciting winding, common winding, and series winding are arranged concentrically, with the exciting winding at the innermost and the series winding at the outermost. One of the return path legs has tertiary winding and tap winding arranged concentrically with the former at the inner side. The capacity of the tertiary winding is 2/3MVA, which is as small as 1/1,000 of the primary capacity. Therefore, to reduce the short circuit current in the event of a short circuit on tertiary system, the tertiary winding is arranged in the return path leg to increase the short-circuit impedance. The series winding and common winding both use interleaved winding, which features superior insulation, cooling, and mechanical characteristics. The series winding has a lead out for high voltage line in the center, which is aimed at lowering the voltages at the edges of the upper and lower winding, thereby simplifying the insulation. Concerning the conductor, the unit comes with a rectangular copper conductor with more than 230MPa as 0.2% proof stress which will meet the strict requirement over the short circuit strength. Especially, the common winding uses self-bonded, low- chip epoxy electrical wire (composite rectangular wire that has been strengthened with the thermal curing of epoxy (see Figure 3)) this is aimed at improving the mechanical strength.

[ Table 2 ] Specifications of the shunt reactor

Transformer
3-1 Cores The unit is a four-legs core construction type. For the core material, 0.3mm-thick, grain-oriented Hi-B silicon steel is applied. To clamp the cores, a bandclamping system using epoxy resin impregnated glass band tape is applied for both the main legs and the

[ Figure 3 ] Low-chip epoxy electrical wire

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3-3 Insulation The multilayer insulation system using an insulation barrier made of pressboard is applied to both the inside and outside of the coil. Generally, the relationship between the gap length and the break down voltage has V-d characteristics, which provide an inversely proportional relationship between the gap length and the break down voltage. Therefore, the configuration and arrangement of the insulation barrier are determined after detailed calculations were made concerning the electrical field in each gap that is conducted through electrical field mapping as shown in Figure 4.

mechanical oscillation have resonance points. Therefore, the clamping force for winding is determined by considering the electromagnetic mechanical force in the event of a short circuit and the oscillation property under normal conditions.

[ Figure 5 ] Multi-nodes oscillation system

[ Figure 4 ]
Electrical field mapping at the bottom of the winding

3-4 Countermeasures for Leakage Flux and Mechanical Oscillation in Winding The leakage flux generated from the winding increases in proportion to the capacity of each leg. This unit comes with a 2,000MVA capacity that is among the world’s largest, and AE Power Systems has applied two-leg type construction for main windings with the optimal construction applied in consideration of local heating caused by leakage flux, stray loss, etc. As measures to reduce the eddycurrent loss inside the winding, the optimal dimensions of the conductor were determined by considering the distribution of leakage flux, and a silicon steel shield, which absorbs the leakage flux, is provided on the inner surface of the tank. Another problem caused by the leakage flux is the mechanical oscillation and noise generated in the winding. To analyze the mechanical oscillation of the winding while the unit is in operation, dynamic analysis using the multi-nodes oscillation system, as shown in Figure 5, has been conducted. Because the insulator is nonlinear, the clamping force for winding and its

3-5 Insulation at the Lead and at the End of Bushing On the 800kV side, the surface of the lead is wrapped in insulating paper to control the electrical field on the surface. The lead is then covered with a multilayer insulation barrier to separate the oil gap, a measure aimed at improving the withstand voltage. The joint of the lead and the bushing is covered with a specially shaped, pulp molded insulation barrier to improve the dielectric strength. This special barrier is molded kraft pulp. It is highly suitable for insulation because it permits great flexibility in shaping to make die and features high dimensional accuracy. The 800kV bushing is of a draw-rod type. Connection with the lead is made at this rod, which facilitates quick connection. 3-6 Cooling System For the cooling system, panel radiators are used, and the transformer has a self-cooling capacity of 60%. When the capacity is 100%, an ODAF type system is applied using the cooling fan and cooling pump.

New Technologies & Products

Shunt Reactor
4-1 Radially Laminated Core Grain-oriented silicon steel is used for the core and features a configuration with a center leg and gapped core. It is a radially laminated core that has a proven

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record of achievement. Figure 6 shows the external view of the radially-laminated core packet. The core packets produced here are larger than the previous ones. Therefore, the experimentally produced core packet was subjected to a resin impregnate test prior to actual production to confirm that the core packet has adequate adhesive strength and longevity corresponding to those of the previous ones. 4-2 Improvement of the Lamination Factor of the Core Packet To reduce the size and weight of the gapped-core reactor, which uses a radially-laminated core, it is important to improve the lamination factor of the core packet. The grain-oriented silicon steels used for the core packet are laminated in the manner shown in Figure 7. Figure 8 shows the relationship between the per-block angle, “ ,” and the lamination factor. As this example shows, an improved lamination factor for the core packet and a smaller external diameter are possible by choosing an appropriate per-block angle.

4-3 Oscillation and Noise Characteristics The oscillation of the shunt reactor is caused by the magnetic attractive force generated at the core gaps or by the electromagnetic force of the winding. Measures taken for the core are as follows: (1) The flux distribution in the gaps is equalized. In other words, the density of magnetic flux at the gaps is made equal by differentiating the dimensions of the gaps at the center of the main legs from the dimensions of those at the end. (2) The gaps use alumina ceramics, which features a module of elasticity that is the same or higher than the core packet and is highly resistant to deterioration over time. (3) The whole core is rigidly clamped in the direction toward the shaft. Empirically, the clamping force here has been set at a much higher level than the magnetic attractive force. For the oscillation at the winding, the appropriate clamping force has been determined through dynamic analysis using a computer, as in the case of the transformers. The measures above have enabled production in full compliance with the specifications in terms of oscillation and noise characteristics.

[ Figure 6 ]
Radially-laminated core packet

[ Figure 7 ]
Lamination pattern of the radially laminated core

[ Figure 9 ] Magnetic field mapping

[ Figure 8 ] Per-block angle,

(degrees)

4-4 Loss All forms of loss, other than the winding resistance loss, are caused by the magnetic flux. Its effect is especially serious with large-capacity equipment, and therefore it is important to precisely determine the magnetic field distribution and resultant loss. To ensure this, magnetic field mapping has been applied to determine the material class and arrangement of each construction material. Figure 9 shows the results of magnetic field mapping.

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4-5 Core Temperatures To reduce the core yoke temperature, the yoke is made wider toward the outer diameter of the packet. Possible causes of the core temperature increasing include the main flux, the leakage flux from the winding and the fringing flux between the core packet and the yoke. Therefore, multiple measures were taken against these factors. For the main flux, the appropriate flux density was set and the cooling ducts were arranged appropriately. As a countermeasure against a temperature increase due to leakage flux, magnetic field mapping was used to optimize the distance between the winding and the yoke. For the fringing flux, magnetic field mapping was also applied to calculate the perpendicular flux to yoke against the fringing flux. The yoke width was optimized in this way, which made it possible to control the magnetic fields that are vertical to the fringing flux and the leakage flux. The temperature at each part was confirmed by setting optical fiber temperature sensors on the core, and no problem was found with the temperature increase at each part. Figure 10 shows the optical fiber temperature sensors mounted on the core.

Postscript
The transformer and shunt reactor features capacities that are among the highest in the world, and AE Power Systems designed and manufactured the units under strict quality control. The tests conducted at the plant showed positive results that comply with the design values. In designing and manufacturing the transformer and the shunt reactor, AE Power Systems has obtained and accumulated a great deal of related technologies. These technologies will play a key role not only in 800kV transformers, but also in a wide range of highvoltage, large-capacity equipment both in Japan and overseas. The technologies will also greatly promote higher reliability, lower loss and smaller size in the future production of transformers and shunt reactors.

New Technologies & Products

Authors

Michinobu FUKUI
Design Department Large Power Transformer Business Unit Transformer Business Division

Keizo KAWANISHI
Manager Design Department Large Power Transformer Business Unit Transformer Business Division

[ Figure 10 ]
Optical fiber temperature sensors mounted on the reactor core

Tests
To test the 800kV reactor, a testing transformer (single-phase 200MVA, 800/ 3/66/18kV) was produced and the necessary facility improvements were made. A long duration induced AC voltage test was conducted at 800/693kV as stipulated by IEC, and it was confirmed that no corona was present in the reactor. It was also confirmed that the reactor is fully capable of enduring the lightning impulse test and the switching impulse test.

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New Technologies & Products

Commercialization of Environmentally Friendly 72kV Dry-Air Insulated Switchgear
Kenji AOYAGI Takeshi IWAIDA Takashi OOMORI

[ Figure 1 ] Environmentally-friendly 72kV dry-air insulated switchgear

AE Power Systems has successfully developed and commercialized the world’s first 72kVclass switchgear that is free of SF6 gas, which is designated as a greenhouse gas. As an alternative, the unit uses highly-pressurized dry-air as the insulation medium. AE Power Systems has overcome the problem associated with the fact that dry air has a lower dielectric strength and lower current switching capability than SF6 gas, while keeping the same external dimensions as conventional SF6 gas insulated switchgears. This switchgear was developed and commercialized to meet the user demand for environmentally-friendly products.

Introduction
SF6 gas, which features outstanding dielectric strength and current switching capability, has been widely used as an insulation and interruption medium. However, the Global Warming Potential

(GWP) of SF6 gas is so exceptionally high – approximately 23,900 times higher than that of carbon dioxide (CO2) – that it was designated as a greenhouse gas at the 3rd Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change (COP3) that was held

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in Kyoto, Japan in 1997. The designation came into effect in February 2005, and since then, SF6 gas has been subject to control. Therefore, reducing the use and emission of SF6 gas has been a great issue to overcome. As a part of the efforts to overcome the problem, research and development of alternatives to SF6 gas have been actively conducted. AE Power Systems had already developed 72/84kV-class tank-type vacuum circuit breakers (VCB) that use dry-air as an alternative to SF6 gas. While VCB is a stand-alone device to switch load current and interrupt fault current, GIS consists of the disconnecting switch (DS) and earthing switch (ES) needed for maintenance work etc., and main bus, lightning arrester (LA), cable head (CH), etc., in addition to VCB. These devices are housed together in a metal enclosure filled with insulating gas, to enable the equipment to be restricted to a compact size. GIS is used mainly for facilities where the installation space is limited. AE Power Systems focused its attention on dry-air as an alternative to SF6 gas, and had been proceeding with development of technologies for using dry-air. Dry-air has a major weak point, that is, much lower dielectric strength and current switching capability compared to SF6 gas. AE Power Systems has made researches over the calculation of acceptable value for insulation designing in dry-air and current switching capability of switchgears. Consequently, AE Power Systems succeeded in developing a SF6 gas free GIS , the world’s first in the 72kV class, by applying a hybrid insulation configuration that combines highly pressurized dry-air and insulating coating of the conductor surface, optimizing the shapes of the conductors and container, etc. An outline of the GIS is given in the following sections.

angles, and selected dry-air as the alternative to SF6 gas because its dielectric strength is the highest of these candidates’ and its GWP is zero. Moreover, there is no risk of accident caused by lack of oxygen during maintenance work.

[ Figure 2 ]
Relationship between GWP and dielectric strength of various gases

Specifications and Construction
Table 1 shows the major specifications of the newly developed GIS. Its rated voltage is 72kV, rated current is 1,200A, and rated short circuit breaking current is 25kA. The rated gas pressure of dry-air is 0.45MPa at the VCB section and 0.5MPa at the bus section, while its minimum gas pressure is 0.4MPa. In accordance with JEC standards, AE Power Systems has conducted a continuous-switching test (10,000 times) for VCB and DS, an interrupting test for VCB, and capacitive-current-switching test, insulation test, short-time withstand current and peak withstand current test, temperature rise test etc. for DS. It was confirmed through these tests that the newly developed GIS satisfies the specified performance requirements.
[ Table 1 ] Specifications of the new GIS

New Technologies & Products

Selection of the Alternative Gas
Figure 2 shows the relationship between GWP and dielectric strength. The value on the vertical axis is set as the standard value, based on the SF6 gas value. The dielectric strength of natural gas existing on the earth, such as dry air (Air) and nitrogen (N2), is about one-third that of SF6 gas. AE Power Systems studied dry-air, N2, CO2 gas and their mixture from various

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Figure 3 shows a cross-section of the newly developed GIS. It is an example of a unit with cable connection. The DS are located above and below the vertically positioned VCB via the three-phase common spacer for gas section, and are connected to the main bus and CH. Arranged between the CH and DS are the ES for earthing power supply side and LA for controlling excess voltage.

can withstand its pressure. This ensures the high reliability of VCB. High reliability of the equipment has been realized by arranging insulating materials like the spacer vertically, and adopting the structure that prevents metallic particles, created by switching of DS, ES, etc., adhering to the insulating materials. Accelerated deterioration tests were conducted to check the oxidization of insulating materials, O-rings, grease, etc. It was confirmed that the tested materials could be used without problems for a longer period than conventional GIS. 4-3 Safety Consideration was also given to the potential pressure increase in the event of ground fault or internal short circuit of GIS. The pressure increase in the dry-air is two to four times larger than in SF6 gas. Therefore, AE Power Systems installed rupture disks in the GIS to prevent the damage to the enclosure and insulating materials in the event of an internal pressure increase. 4-4 Maintainability The gas section for the VCB is separated from the main bus and DS section. This means that, when VCB is inspected or replaced, the gas processing for the main bus and DS section is not necessary, and the main bus and other circuits do not have to be disconnected because the insulated state is retained.

[ Figure 3 ] Cross section of the new GIS

Features
4-1 Compact Size For the newly developed GIS, AE Power Systems has applied a gas/solid hybrid insulation configuration that combines the highly pressurized dry-air and insulating coating of the conductor surface. This has made it possible to achieve nearly the same external dimension as those of SF6 gas insulated switchgears from AE Power Systems. The optimum arrangement of the conductors and the use of cast conductors and containers have realized equipment with compact dimensions, eliminating the unnecessary space for the gas. In addition, AE Power Systems has developed a plug-in type LA that facilitates attachment and removal from outside of the GIS. This has also contributed to the compact dimensions of the new GIS, because it eliminated the need to install an LA disconnector, which was necessary with the conventional configuration. 4-2 Reliability To install the VCB in highly pressurized (0.45MPa) dry-air, AE Power Systems developed bellows that

Summary
In developing the new GIS, AE Power Systems focused its attention on dry-air as an alternative to SF6 gas, and succeeded in developing the world’s first 72kV class SF6 gas free GIS. The development was made possible by a hybrid insulation structure that combines the highly pressurized dry-air and insulating coating of the conductor surface, the optimized shapes of the conductors and container and etc. The external dimensions of the new GIS are almost the same as those of the conventional GIS that adopts SF6 gas. The new GIS meet the users environmentally-friendly requirement. Since the operation of the first unit started in June 2005, AE Power Systems has delivered the newly developed

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GIS to railroad companies, public facilities, and other users. AE Power Systems will continue its efforts to promote this new GIS.

Reference
(1) Rokunohe, T. et al. Development of 72kV GIS in High Pressure Air with Vacuum Circuit Breaker. I.E.E. Japan Transactions on Power and Energy, Vol. 125-B, No.12, 2005, p.1270-1277.

Authors

Kenji AOYAGI
Design Department, High Voltage Switchgear Business Division A member of the Institute of Electrical Engineers of Japan

Tekeshi IWAIDA
Design Department, High Voltage Switchgear Business Division A member of the Institute of Electrical Engineers of Japan and the Japan Society of Mechanical Engineers
New Technologies & Products

Takashi OOMORI
Manager Design Department, High Voltage Switchgear Business Division A member of the Institute of Electrical Engineers of Japan

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New Technologies & Products

Development of 24kV Cubicle-Type Dry-Air Insulated Switchgear
Nobuaki TAMAKI Kazunori NAITO Terumichi CHOU

[ Figure 1 ] 24kV Cubicle-type dry-air insulated switchgear

AE Power Systems developed an environmentally-friendly 24kV cubicle-type dry-air insulated switchgear, which does not use SF6 gas, specified as Global Warming Potential. The following sections show the results of the basic test and compare the structures and features of the new switchgear with those of conventional switchgear using SF6 gas.

Introduction
AE Power Systems commercialized SF6 gas insulated switchgears that use 24 to 204kV vacuum circuit breakers from the 1980s, and has delivered them to electric power utililies and private industries. However, AE Power Systems is currently developing a variety of equipment that is free of SF6 gas based on

the findings of research into dry-air insulation, which AE Power Systems has been engaged in to reduce the amount of SF6 gas used. The following sections present the details and technologies of environmentally-friendly 24kV cubicle-type dry-air insulated switchgear with low gas pressure, which has been produced in such trends.

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Dry Air Insulation Technology
Gases that have a minimal burden on the environment include air, nitrogen (N2), and carbon dioxide (CO2). However, the dielectric strength of these gases is only about one-third that of SF6 gas under a quasi-uniform electric field. Therefore, to use these gases for switchgear without making it larger than the equipment currently used, the gas pressure needs to be increased and composite insulation such as coating needs to be applied. The developed 24kV cubicle-type dry-air insulated switchgear, features the appropriate arrangement of devices in the tank and allowed dry-air insulation at low gas pressure by optimizing the conductor shapes, and incorporating composite insulation technologies including coated conductors. In selecting the insulating gas, CO2, a greenhouse gas, was eliminated as a candidate, and an insulating performance test was conducted to compare air and N2 gas, which have the same level of dielectric strength. As a result, dry-air was selected because its lightning impulse withstand voltage was found to be more stable. Subjects of the basic research of alternative gas insulation, such as this dry-air insulation, include basic insulation properties of insulation materials, electrical field dependence, and the dielectric breakdown mechanism of composite insulation. Figure 2 shows an example of the results of the basic insulation property test of insulation materials with a needle-plane electrode (under a relatively non-uniform electric field).

New Technologies & Products

[ Figure 2 ]
Basic insulation properties of insulation materials

Construction and Rating
Figure 3 shows the construction of the incoming panel, and Table 1 shows the rating of each device. The construction of the incoming panel features the separate gas sections for the VCB compartment and the main busbar compartment – which is same as that of conventional GIS. The VCB compartment houses the vacuum circuit breaker (VCB), disconnecting switch with earthing switch (EDS), earthing switch (ES), and lightning arrester (LA). Bushings are used for the connection with the metering outfit.
[ Figure 3 ] Structural drawing of the incoming panel

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3-1 Complete unit of C-GIS Conventional GIS uses SF6 gas. Therefore, it was necessary to strengthen the tank to prevent the gas leak in the event of an internal arc fault, which causes a rapid increase in pressure and may fracture the tank. But the new cubicle-type GIS (C-GIS) uses dry-air, which may be discharged externally. Therefore, AE Power Systems installed a pressure relief device in the unit to prevents the damage caused by pressure increase inside the tank in the event of an internal arc fault. This enabled the tank walls to be thinner, thereby reducing the tank weight by 20% – 30%. The

unit also comes with a small-sized LA using highresistance element, which is placed within the bottom of the tank. This eliminated the need to modify the structure in a direction toward the cable from the main circuit, permitting a standard design for the new C-GIS (see Figure 4). 3-2 Vacuum Circuit Breaker (VCB) The vacuum interrupter (VI) is positioned vertically, not horizontally, in order to downsize the unit. An improved Cu-Cr electrode material is used for the VI in the arc-extinguish chamber, which makes

[ Table 1 ] Rating

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Features
4-1 Shorter Installation Period The lightweight nature of this product allows multiple units to be transported at one time, and a shorter installation period. Additionally, the low gas pressure permits the C-GIS to be transported to the site maintaining the condition of its shipment from the factory (i.e., the unit permits transportation with the rated amount of dry-air charged in the tank), and the quality of the unit, is not degraded even after installation at site. For example, in the case of a standard single line with two incomings, two transformer banks and one metering panel (2L-2B-1VCT), the units can be simply set in position and fasten them. This is possible by installing the 2L and 2B on both sides of the metering panel. Even when multiple units are are transported separately, dry-air processing is necessary only for the connections between the units on site because the dry-air is appropriately sectionalized inside the unit. 4-2 Safety and Conservation of Resources and Energy The insulating material of this C-GIS is dry-air. Unlike SF6 gas, dry-air does not cause global warming when it leaks into the atmosphere, and it also ensures the safety of the workers. The main circuit conductors are optimized and composite insulation is minimized in consideration of the recycling rate (percentage weight: 75%) at the time of replacement or disposal. 4-3 Maintainability and Inspections The unit uses a VCB that permits easy maintenance and inspection. The main circuit portion is housed in a hermetically sealed grounded metal enclosure which keeps it unaffected by the external atmosphere containing water contents and dust. This permits maintenance-free operation of the main circuit. The monitoring device and the operating mechanism parts are all positioned in front for improved maintainability. The only required maintenance work is lubrication and measurement tests (insulation resistance test, switching characteristics test, etc.) of the operating mechanism for each unit.

New Technologies & Products

[ Figure 4 ]
Comparison of structures – Conventional GIS and the Cubicle-type dry-air insulated switchgear

the unit more reliable in terms of anti-adhesiveness, interruption performance, and insulation. This also reduces the power required for operation. Moreover, even when the charged pressure is reduced to the level of atmospheric pressure, the unit’s insulation design enables it to endure a nominal operation voltage and transient recovery voltage caused by fault current breaking, permitting switching operations. 3-3 Disconnecting Switch with Earthing Switch (EDS) The structure of this device features a combined disconnecting switch and earthing switch, to downsize the unit. To optimize the shape of the disconnecting switch, AE Power Systems has succeeded in applying in dry-air a blade-shaped three-position system (earthing, disconnecting, and connecting position) that has been used for the conventional GIS.

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To check the vacuum degree, where conventional method is to measure the withstand voltage across the contacts, the unit is equipped wiht vacuum monitoring device which enables to monitor the vacuum degree without shutting down the unit. The principle of the vacuum monitoring device is shown in Figure 5, and its external view is shown in Figure 6.

[ Figure 5 ] Measurement principle

References
(1) Saito, H. et al. Impulse Partial Discharge and Breakdown Characteristics of Rod-Plane Gaps in Air and N2 Gases. I.E.E. Japan Transactions on Power and Energy, Vol. 123-B, No. 2, 2003. p.169-174. (2) Akiyama, S. 24kV Ky?bikurushiki Kuukizetsuen Kaiheisouchi. Denki to Kouji (Magazine of Electrical Construction Engineering), Ohmsha, Ltd., November Issue, 2005.(in Japanese)

[ Figure 6 ] Vacuum monitoring device

Authors

Conclusion
Given the increasing problem of global warming, environmentally-friendly products are becoming increasing demand. AE Power Systems intends to increase the line-up of environmentally-friendly products that apply dry-air insulation technologies. By providing the customers with such products, AE Power Systems will contribute to the prevention of global warming and a reduced burden on the environment.

Nobuaki TAMAKI
General Manager Design Department Medium Voltage Switchgear Business Division A member of the Institute of Electrical Engineers of Japan

Kazunori NAITO
Manager Design Department Medium Voltage Switchgear Business Division

Terumichi CHOU
Manager QA & Inspection Department Medium Voltage Switchgear Business Division A member of the Institute of Electrical Engineers of Japan

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Recent Technology Trend in Vacuum Circuit Breaker
Hitoshi SAITO Yoshihiko MATSUI Masayuki SAKAKI

New Technologies & Products

[ Figure 1 ] Recent Product Trends and Basic Technologies of VCB

This article introduces the recent technological trends of vacuum circuit breakers (VCB), focusing on; (1) higher voltage and larger capacity of VCB and technologies for interruption and electrode materials; (2) dry-air insulation technologies that satisfy the demand for equipment that does not use SF6 gas, and the application of those technologies for the development of ecologically-friendly circuit breakers; (3) trends toward lower total lifecycle costs (LCC) (technologies for solenoid operating system with permanent magnet latch mechanism), and; (4) new applications and entering to the new markets with products applying the features of VCB. Future prospects of the trend are also given in the final section of this paper (see Figure 1).

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Introduction
Due to its small size, small operating force, easy maintenance, frequent current breaking capability, and other benefits, VCBs, mainly in the medium- to low-voltage classes, below 72kV have been widely used for electrical power systems. In addition to these properties, VCBs have found widespread application due to the fact that no SF6 gas, designated as a greenhouse gas, is used to interrupt the current. The following section describes the recent trend and basics of technologies of VCBs.

with the magnetic field analysis and measurement (see Figure 2).

Basic Technologies and Product Trends
2-1 Higher Voltage and Larger Capacity VCB started to be widely used in the 1960s. Efforts to increase the voltage were already made during this initial period, and 84kV single-break units and 168kV double-break units were produced in the 1970s(1). These circuit breakers represented a breakthrough in those days, but the transverse magnetic field electrodes were used, and the vacuum interrupter (VI) was large with complex shield structures. In the 1980s progress was seen, such as the introduction of Cu-Cr electrode material and the application of axial magnet field electrode, which features superb interrupting capability, and the development of 72/84kV ceramic VI in the latter half of the 1990s. Then in the 21st century, 120kV/31.5kA single-break VCB and 168kV/40kA double-break VCB were developed through the experimental production of 145kV single-break VCB(2). The following paragraphs outline the technologies that contributed to the development. (1) Larger Capacity The larger interrupting capacity was made possible by the development of axial magnet field electrodes. These new electrodes feature less partial melting of the electrode surface than the previous transverse magnetic field electrodes, which is advantageous for the application to the high-voltage and large-capacity range. To optimize the structure of the new electrodes, arc observation has been conducted along

[ Figure 2 ]
Examples of magnetic field analysis of axial magnet field electrode and arc observation

(2) Higher Voltage To ensure higher withstand voltage, Cu-Cr alloy with high Cr content was adopted, which improved not only the withstand-voltage performance but also the current-carrying performance. In addition, AE Power Systems has achieved a withstand-voltage performance that is higher than conventional units. This was enabled by combining the conditioning effect, which eliminates the oxidative products and minute projections on the electrode surface, and with the optimization of the shape by electrical field strength analysis (see Figure 3).

[ Figure 3 ] Example of electrical field analysis

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(3) Application to Circuit Breakers The benefits of a dead-tank type circuit breaker include higher anti-seismic characteristics compared to the live-tank type circuit breaker and bushing CT can be directly mounted. But its disadvantage is that the VI’s withstand voltage across contacts is lowered by the effect of the grounded tank. This was overcome by applying technologies of raising the VI voltage, which allows the unit to have sufficient performance over the withstand voltage across contacts even when it is installed inside the tank. Consequently, the world’s first 120kV single-break dead-tank type VCB was produced successfully (see Figure 4). The 168kV double-break dead-tank type VCB is equipped with a grading capacitor for equalizing the voltage of respective VI.

only about one-third that of SF6 gas under the same pressure. Therefore, to allow a dry-air insulated VCB to have the same physical dimensions as those of conventional units, a higher gas pressure is used and a composite insulation technology, which provides an insulating coating on the conductor surface, is applied for the VCB (see Figure 5).

New Technologies & Products

[ Figure 5 ] Composite insulation & dry-air

[ Figure 4 ]
Sectional drawing of 120kV single-break dead-tank type VCB

2-2. SF6 Gas Free Units (1) Air Insulation System Because VCB uses a vacuum in the arc extinguish chamber, it becomes a complete SF6 gas free circuit breaker when dry-air is used for insulation. Generally, the insulating performance of dry-air is

(2) VI with High Withstanding Pressure When the VI is set under a high gas pressure, it is subject to excessive stress caused by the pressure difference from the vacuum. What needs to be overcome in particular is the buckling of the bellows, which is used to keep the vacuum when the VI is opened or closed. AE Power Systems developed an external pressure system, which adds pressure to the bellows from the outside. This permits a higher withstanding pressure, because it is less likely to cause buckling of the bellows than the conventional internal pressure system (see Figure 6). A verification test was conducted by repeating the

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New Technologies & Products

switching operations with a pressure difference of six atmospheres, which verified that the unit is able to perform 10,000 switching operations during its life. Applying this VI with high a withstand pressure, AE Power Systems developed a 72/84kV dry-air insulated dead-tank type VCB for the first time in the world(3). The technologies for this VCB have been applied more widely, and are now also used for the interrupting part of 72kV dry-air insulated GIS(4).

2-3 Less Total Life Cycle Cost (LCC) (1) High-Efficiency Solenoid Operating Mechanism with Magnetic Latch Mechanism AE Power Systems developed a solenoid operating system with permanent magnet latch mechanism, which permits exceptionally easy operation with no complicated gears or mechanical latches(5). This mechanism features a ring-shaped Nd-Fe-B (neodymium iron boron) permanent magnet, closing and tripping coils, a shaft bush, etc. housed in a container, with the plunger integrated into the operating shaft and the shaft bush positioned at the center and the opening spring mounted on top (see Figure 7). The total number of parts is only 18, which is much fewer than that of the conventional spring operation mechanism consisting of 50 parts. Additionally, oil-less bearings are used for the sliding parts of the operating shaft and the plunger. This reduces troublesome maintenance work that arises with the use of grease.

[ Figure 6 ]
Cross sections of conventional VI and VI with high withstand pressure (The colored parts are vacuum.)

(3) Dry Air Insulation with Low Gas Pressure A cubicle-type gas insulated switchgear (C-GIS) uses low gas pressure and its conductors have a nonuniform electric field. Therefore, the insulation for CGIS is designed with a different idea to that for designing GIS. The corona stabilization effect can be expected at around range of two atmospheres from the atmospheric pressure, allowing the breakdown voltage of the air at two atmospheres to be almost the same level as that of SF6 gas at atmospheric pressure. Making use of this feature, AE Power Systems developed a cubicle-type dry-air insulated switchgear with a 24kV rated voltage. Because this unit uses dry-air with a 0.1MPa rated gas pressure as the insulating gas, the VI for the unit does not have to be designed for high withstanding pressure and standard VI can be used, which reduces cost.

[ Figure 7 ]
Structure (closed position) of solenoid operating system with magnetic latch mechanism and result ofgripping force analysis

(2) Lower Operating Current For the above solenoid mechanism, AE Power Systems has conducted flux control and optimization of its magnetic circuit, based on the recent improvement in permanent magnet materials and the development of coupled analyses that use electromagnetic field transient analysis techniques and of mechanism analyses. This has made it possible to maximize the energy of the coil. Consequently, AE

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Power Systems has succeeded in reducing the peak value of the operating current to less than 50% compared with the original value, and made it unnecessary to use the electrolytic capacitor for assisting the power supply, which needs regular replacement. 2-4 Broader Applications The following section shows examples of the broader applications of VCB, which is enabled by a variety of features. (1) 24kV High-Speed Vacuum Circuit Breaker for Phase Modifying Operation The Hokkaido-Honshu HVDC link (which started operation in December 1979), operated by the Electric Power Development Co., Ltd., uses an external commutated inverter. Therefore, the link consumes the inductive reactive power. Facilities performing the phase modifying operation are required to stabilize the system voltage. At the Hokkaido-Honshu HVDC link, the circuit breaker that performs the phase modifying operation will be replaced because it has been in operation for more than 27 years. For the replacement, AE Power Systems has developed a 24kV high-speed vacuum circuit breaker for phase modifying operation, which follows shutting down and rebooting the transducer in the event of a fault in the AC system and permits multiple switching operations in a short time (conducts each closes and opens operation four times each in two seconds) (see Figure 8)(6). To enable the existing circuit breaker to be replaced with the new unit, AE Power Systems has ensured complete compatibility of the newly developed product in terms of the high-voltage conductor part and connections with the panel. In addition, the spring operation system of the old equipment was replaced with magnetic operations to permit four closing and opening movements in two seconds.

[ Figure 8 ]
High-speed vacuum circuit breaker for phase modifying operation

achieve higher voltage and larger capacity in the future, it is necessary to overcome the issues of higher cost and smaller current-carrying capacity due to poor cooling efficiency in the vacuum, as compared with GCB. VCB is ecologically friendly equipment, and units that use dry-air as an alternative to SF6 gas for insulation will become the majority. Units up to 72kV will be adopted even more widely. The more energy conservation and lifecycle costs increases, the greater the demand for improved maintainability without the use of grease etc., and for a shift in the diagnostic function from TBM[1] to CBM[2]. Regarding the operating mechanism, reducing the operating current is an important issue, and it is expected that products that apply solenoid operator with magnetic latch mechanism, mainly units in the low-voltage class, will be used more widely.

New Technologies & Products

Conclusion
This article provided the outlines of recent technological and product trends in VCB, including the trend toward higher voltage and larger capacity, a reduction in the burden on the environment, lower LCC, and broader applications. The future prospects for the and trends were also given in this paper.

Future Trends and Issues
Expectations have increased for VCB as the only high-voltage, large-capacity circuit breaker that does not use SF6 gas as an interruption medium. To

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References
(1) Takashima T. et al. 168kV class Vacuum Circuit Breakers. Meiden Review. No.2 1979 p.9-16. (2) Matsui Y. et al. Development and Technology of High Voltage VCBs; Breaf History and State of Art. Discharges and Electrical Insulation in Vacuum, 2006, ISDEIV '06, International Symposium on. vol.1, 2006, p.253-256. (3) Nagatake, K. et al. Development of Environmentally Benign Type 72/84kV Vacuum Circuit-Breaker, the 2003 Annual Meeting Record of Power and Energy Society of I.E.E. Japan, Vol. B, 2003, p.143144. (4) Rokunohe, T. et al. Development of 72kV GIS in High Pressure Air with Vacuum Circuit Breaker. I.E.E. Japan Transactions on Power and Energy, Vol. 125-B, No.12, 2005, p.1270-1277. (5) Tsuruta, T. et al. Technology of highly effective Electromagnetic Actuator wiht magnetic latch system for VCB. the 2007 Annual Meeting Record of Power and Energy Society of I.E.E. Japan, 2007, p.11-19, 11-20. (6) Ota, A. et al. Development of 24kV phase of Modified High Speed Vacuum Switch. the 2008 Annual Meeting Record of I.E.E. Japan, Vol. 6, 2008, p.333.

Authors

Hitoshi SAITO
Development Department Medium Voltage Switchgear Business Division Doctor of Engineering Member of the Institute of Electrical Engineers of Japan

Yoshihiko MATSUI
Chief Engineer Development Department Medium Voltage Switchgear Business Division Senior member of the Institute of Electrical Engineers of Japan

Masayuki SAKAKI
Director Development Department Medium Voltage Switchgear Business Division Member of the Institute of Electrical Engineers of Japan

[1] Time based maintenance [2] Condition based maintenance

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Preventive Maintenance Technology for Low-Viscosity Silicone-Fluid Immersed Transformers and Its Progress
Akira YAMAGISHI Hiroyuki SAMPEI Katsunori MIYAGI Yukiyasu SHIRASAKA

New Technologies & Products

[ Figure 1 ]
(a) 66kV 5,000kVA low-viscosity silicone fluid-immersed transformer (b) Internal structure

Silicone fluid, its featured characteristics being fire safety and low environmental impact, has drawn attention as an insulating and cooling medium for transformers. AE Power Systems, ahead of other transformer companies, has selected low-viscosity silicone fluid (kinetic viscosity: 20cSt @ 25 ) that features: (1) high flash point (over 250 ) for fire safety; (2) degradability in soil for low environmental impact, and; (3) nearly equivalent insulating and cooling properties to those of mineral oil. This allowed AE Power Systems to complete the first unit of a low-viscosity silicone-fluid immersed transformer (hereinafter called a silicone-fluid immersed transformer) in the 22kV class in 2003. In 2005, AE Power Systems commercialized a 66kV compact size silicone-fluid immersed transformer using high-temperature insulation material. AE Power Systems improved the preventive maintenance technology for silicone-fluid immersed transformers and enabled the diagnosis similar to that used for mineral-oil immersed transformers.

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[ Table 1 ] Dissolved gas concentration threshold levels for silicone fluid and mineral oil (ppm)

1 : IEEE Std C57.146-2005, IEEE Guide for the Interpretation of Gases Generated in Silicone-immersed Transformers, p. 6. 2 : Electric Technology Research Association (Japan), “Maintenance management for oil-immersed transformers,” Denki Kyodo Kenkyu, Vol. 54, No.5 (1), 1999, p. 45. (in Japanese)

Preface
To improve the preventive maintenance technology and to ensure further reliability of silicone fluidimmersed transformers (see Figure 1), AE Power Systems has studied the possibility of applying abnormality diagnosis and life diagnosis that are similar to those used for mineral-oil immersed transformers.

Study of Abnormality Diagnosis

model, and Figure 2 (c), a needle-plane electrode model, show that methane (CH4) tends to be predominant when the partial discharge energy is low. It is similar to the pattern for overheating caused by poor electrical continuity or leakage current in mineral oil. IEEE suggests guidelines for abnormality diagnosis of silicone fluid using gas analyses (see Table 1). The guidelines show that the threshold level of carbon monoxide (CO) is larger than the threshold level for mineral oil as stipulated by the Electric Technology

The gas pattern diagnosis of mineral-oil immersed transformers was applied to study the gas patterns of silicone-fluid immersed transformers. Figure 2 (a), a kraft paper model, shows that hydrogen (H2) becomes predominant and the amount of acethylene (C2H2) also increases. Figure 2 (b), an aramid paper model, and Figure 2 (c), a needle-plane electrode model, show H2 is predominant and C2H2 increases when the total partial discharge energy is high. H2 predominant pattern often indicates faults caused by partial discharge or electrical arc in the case of mineral oilimmersed transformers. Figure 2 (b), an aramid paper

[ Figure 3 ]
Relationship between the amount of CO2+CO in silicone fluid and retained tensile strength of kraft paper after accelerated aging test

[ Figure 2 ]
Relationship between total partial discharge energy and gas patterns for kraft paper model, aramid paper model, and needleplane electrode model in low-viscosity silicone fluid

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Research Association (Japan). Its reason is believed to be in the difference in chemical reaction processes.

Study of Life Diagnosis
The indexes on aging used for the life diagnosis of mineral oil-immersed transformers, which are the amount of CO2+CO and furfural content, are applied for a silicone fluid-immersed transformer. Figure 3 is the data from using a kraft paper model in silicone fluid. It shows that a correlation is found between the amount of CO2+CO and retained tensile strength after an accelerated aging test. This enables estimating the degree of paper aging. Figure 4 shows a correlation is found between furfural content and average degrees of polymerization for kraft paper. As furfural is not caused by aging of silicone fluid, it is possible to accurately estimate the degree of paper aging. Figure 5 is the data from using the aramid paper

model in silicone fluid. It shows that the aramid paper hardly deteriorates after an accelerated aging test. As cyclic siloxane (D3+D4+D5) of polydimethylsiloxane is generated by the aging of silicone fluid, it is applied as an index of silicone fluid aging.

Summary
The preventive maintenance technology for silicone fluid-immersed transformers was established by applying the diagnosis similar to that used for mineral oil-immersed transformers. The aging index that is specific to silicone fluid made further improvements in reliability. Acknowledgement AE Power Systems would like to thank The Kansai Electric Power Co., Inc., Nagoya University, Shin-Etsu Chemical Co., Ltd., and Hitachi Ltd., for their cooperation in this research.
New Technologies & Products

Authors

Akira YAMAGISHI
Design Department, Medium Power Transformer Business Unit Transformer Business Division Member of the Institute of Electrical Engineers of Japan

Hiroyuki SANPEI
Deputy Senior Manager Medium Power Transformer Business Unit Transformer Business Division Member of the Institute of Electrical Engineers of Japan

[ Figure 4 ]
Relationship between furfural content and average degrees of polymerization retained in kraft paper after accelerated aging test

Katsunori MIYAGI
Manager Research & Development Management Department Research & Development Division Doctor of Engineering Member of the Institute of Electrical Engineers of Japan

Yukiyasu SHIRASAKA
Chief Engineer Large Power Transformer Business Unit Transformer Business Division Member of the Institute of Electrical Engineers of Japan Member of CIGRE

[ Figure 5 ]
Relationship between the amount of cyclic siloxiane (D3+D4+D5) in silicone fluid and volume resistivity of silicone fluid after accelerated aging test

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Development of Oil Palm Fatty Acid Ester Insulating Oil
Environmentally-Friendly Vegetable Oil-Based Insulating Oil for Transformers
Hidenobu KOIDE Tomoyuki HIKOSAKA Yasunori HATTA Akina YAMAZAKI

In response to the growing trend in recent years toward regulating the use of fossil resources to protect the global environment, AE Power Systems has developed vegetable oil-based oil palm fatty acid ester insulating oil ( PFAE) to be used for transformers as an alternative to mineral oil. PFAE features low-viscosity (60% that of mineral oil) and high relative permittivity (1.3 times higher than that of mineral oil). When applied to oil-immersed transformers as insulating oil, PFAE ensures superior supply stability, insulating performance, and cooling characteristics. It has been demonstrated that PFAE is promising insulating oil for transformers, which ensures improved performance while meeting environmental protection requirements.

Preface
There has been a growing trend in recent years toward regulating the use of fossil resources as countermeasures against environmental degradation. In the field of transformers, interest in using environmentally-friendly insulating oil as an alternative to the mineral oil, which has been widely used, is increasing. In a joint development project with Lion Corporation, AE Power Systems has developed PFAE for transformers by using palm oil. PFAE ensures superior supply stability, insulating performance, and cooling characteristics. The properties of PFAE are described in the following sections.

Properties of PFAE
2-1 Supply Stability Because transformers are operated for decades, stable supply of insulating oil is essential. Oil palms, the base material of PFAE, are grown in tropical areas and their fruits are harvested in clusters called bunches. Palm oil is taken from the palm fruits and the palm kernel oil is extracted from the seeds (see Figure 1). The amount of oil palm production is 36 million tons per year; most produced vegetable oil in the world. Oil palms also have an outstanding rate of harvest per unit area, much higher than other plants (see Figure 2), which resolves any problems in terms of supply stability.

[ Figure 1 ] Oil palm (tree and fruit)

[ Figure 2 ] Supply stability

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[ Figure 3 ] Results of oxidation stability tests (in accordance with JIS C2101)

2-2 Property Comparison between PAFE and Mineral Oil Table 1 compares the properties of PFAE with those of mineral oil. PFAE has the following advantages: (1) Its low viscosity ensures higher cooling efficiency when used in transformers. (2) It features high relative permittivity, and increases breakdown voltage of the oil impregnated insulation system through the effect of matching the permittivity with the insulation material. (3) Its flash point is higher than mineral oil. (4) Because it is vegetable-based oil, it ensures stable supply without the possibility of exhaustion. (5) Since it is biodegradable, even if it leaks into the soil, it immediately degrades into H2O and CO2. When PFAE is used for transformers, the properties above are expected to ensure higher insulating characteristics, higher cooling characteristics, and smaller equipment size than the transformers using mineral oil.

2-3. Oxidation Stability AE Power Systems has conducted oxidation stability tests of mineral oil and PFAE in accordance with Japanese Industrial Standard, JIS C2101. Figure 3 indicates photographs of mineral and PFAE before
New Technologies & Products

[ Table 1 ] Property comparison

[ Figure 4 ] Acidity comparison

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New Technologies & Products

and after the tests conducted under three different treatments of insulating oil. As the photographs show, mineral oil turns reddish brown under any of the three treatments, while PFAE shows no change in color after the tests, remaining transparent under all three kinds of treatment. Comparisons of acidity were also conducted before and after the tests, and it was found that PFAE underwent no change in acidity and retained low values (see Figure 4). This demonstrates that PFAE has superior oxidation stability characteristics. 2-4 Insulating Characteristics AE Power Systems has conducted AC and lightning impulse voltage withstand tests by using an intersection model (see Figure 5) as a composite insulation model for transformers. The wire used for the model is a 3 mm x 13 mm rectangular copper conductor insulated with 0.3 mm thick kraft paper. A 4.5 mm-thick high-density pressboard was used as the spacer. Figure 6 shows the results of the tests. The partial discharge voltage of AC and lightning impulse was 1.3 to 1.5 times higher when PFAE was used than when mineral oil was used. This seems to be attributable to the reduced charge of voltage on the wedge-shape oil gap, due to the permittivity matching effect between the PFAE and the insulating paper.

[ Figure 6 ] Partial discharge voltage of inter-section model

Authors

Hidenobu KOIDE
Manager Administration Department Transformer Business Division Member of the Institute of Electrical Engineers of Japan

Tomoyuki HIKOSAKA

Yasunori HATTA [ Figure 5 ] Form of inter-section model
Administration Department Transformer Business Division Member of the Institute of Electrical Engineers of Japan

Postscript
Akina YAMAZAKI

It was demonstrated that the PFAE developed by AE Power Systems is environmentally-friendly insulating oil, excellent in supply stability, insulating characteristics, cooling characteristics and durability. AE Power Systems will further contribute to the society by commercializing PFAE for transformers.

Administration Department Transformer Business Division Member of the Institute of Electrical Engineers of Japan

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Trend of New Technologies for Insulation Diagnosis and Monitoring of Substation Equipment
Katsunori MIYAGI Yujiro YAGI

With the large number of aging substation equipment in service, the effective performance of maintenance has been studied, and there has been growing demand for advanced external diagnosis technologies that will enable meticulous monitoring of equipment conditions. This article describes the research progress in: (i) technology for diagnosing the partial discharge of oil-immersed transformers using a wavelet analysis processor for signals detected by an AE sensor; (ii) technology for diagnosing the partial discharge of GIS using a neural network processor for UHF sensor output signals, and; (iii) technology for diagnosing the vacuum degradation of vacuum interrupters using a vacuum monitoring system that applies the Paschen's Law on discharge voltage and vacuum level.
New Technologies & Products

Introduction
A large number of substation equipment installed in Japan’s high-growth period will soon exceed 30 years in age, and its deterioration with age are expected to increase. Also, in the era of deregulation of the electricity market , the improvement of effective diagnosis and maintenance technologies is becoming increasingly important to ensure extended use of those facilities without affecting the power supply

reliability. In overseas countries, the setting of a new standard has been considered concerning partial discharge measurement using an AE and UHF sensors, and its development will be closely watched(1). Generally, a substation consists of gas insulated switchgears (GIS), transformers, and switchgears. The following sections describe the new insulation diagnosis and monitoring technologies regarding the preventive maintenance of this substation equipment.

[ Figure 1 ] Skeleton of partial discharge monitoring system

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[ Figure 3 ] Wavelet analysis of AE sensor signals

Technologies for Insulation Diagnosis of Oil-Immersed Transformers
A partial discharge (PD) in an oil-immersed transformer creates not only electrical pulse currents but also acoustic waves that have a wide range from audio frequencies to ultrasonic frequencies . Therefore, the PD is checked either by detecting the electrical pulse or by detecting the acoustic waves transmitted through the insulating oil. The following paragraphs describe a technology for partial discharge diagnosis, which enables the PD signal detected by AE sensor and other signals to be distinguished by using a wavelet analysis. 2-1 Partial Discharge Monitoring System Figure 1 illustrates the conventional PD monitoring system, which consists of: (i) the electrical pulse method that detects electrical pulses using a highfrequency CT installed in the grounding wire of the transformer , and; (ii) AE measuring system that detects acoustic pulses using an AE sensor mounted on the outer wall of the transformer’s tank. This system detects the location of the PD by comparing the electrical pulse signals with acoustic pulse

signals(2). Figure 2 shows the example of an AE sensor. 2-2 Partial Discharge Detector that Applies Wavelet Analysis PD detection using AE sensor permits easy measurement and is resistant to electromagnetic noise. However, this method is affected by noise generated by surrounding physical sound, such as rain or wind. Therefore, AE Power Systems has attempted to eliminate noise by using wavelet analysis, which is widely known as an effective method of analyzing vibration. The wavelet analysis is a type of time-frequency analysis that the detected waveform data is used for two-dimensional analysis (on time and frequency axes) to obtain the waveform energy distribution. Figure 3 (a) shows an example of the result of wavelet analysis, which was performed for signals detected by AE sensor when a mechanical pencil lead was broken to simulate the PD sound. As shown by the result of this analysis, remarkable signals are observed between 100kHz and 140kHz, and the range of the detected signals is so wide as to include those at 40kHz. Figure 3 (b) and Figure 3 (c) show the results of calculation of signals detected by AE sensor when a discharge occurred at a void in oil. The electrical charges of the PD are around 20pC and around 50pC, respectively. In both examples, the signals fell in the frequency range between 80kHz and 180kHz, with the remarkable signals detected between 130kHz and 150kHz, allowing the PD sound to be distinguished from noise sound(3). The AE partial discharge detector applying the wavelet signal conversion process, developed by AE Power Systems this time, allows PD signals to be

[ Figure 2 ] An example of AE sensor

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distinguished from noise signals. Application of the newly developed detector in the field is expected.

Technology of Diagnosing the Insulation of GIS
Generally, GIS uses SF6 gas, and the frequency of signals for a PD that occurs within GIS is as high as several hundred MHz, or even higher (UHF band). This permits highly sensitive detection of the signals using an antenna or similar devices. The signals in this frequency range can be detected even when they are very weak, and even in a place like a substation where there is relatively high noise. The following paragraphs describe the technology for diagnosing the GIS insulation, which features high sensitivity and a high SN ratio. 3-1 UHF Partial Discharge Sensor There are two types of PD sensors: (i) internal sensors that are built in the GIS during its production, and, (ii) external sensors that are mounted on the outside of GIS when the signals are measured. As shown by Figure 4, internal sensors are generally more sensitive than external mount type(4). Figure 5 shows an example of a sensor installed on the equipment(5). According to the reduction in size, weight, and cost as well, simpler configuration of sensors achieved in recent years, internal sensors are provided as standard accessories.

3-2 Insulation Diagnosis Device that Applies UHF Method PD output from the UHF sensor is diagnosed using frequency analysis and phase analysis. In frequency analysis, the frequency range of output signals from the UHF sensor is specified with the spectrum analyzer, and signals that appear in the frequency range are quantified. On the other hand, phase analysis develops the patterns of causes and types of abnormalities based on the UHF sensor outputs’ phase spectrum patterns that vary among PD sources. Figure 6 shows examples of the causes of abnormality and phase spectrums from the UHF sensor. The phase spectrum patterns are specific to each cause of the abnormality, which permits the sources of the detected UHF signals(6) to be identified. Figure 7 shows a conceptual diagram of the diagnostic devices used for actual equipment. As the diagram shows, these devices apply a diagnostic algorithm that has a neural network structure for conducting split diagnosis based on the frequency spectrum and phase spectrum. It has been confirmed that these devises ensure an accuracy rate of 97% or higher for diagnosing the presence/absence of PD that of 90% or higher for identifying the cause of PD(6). These diagnostic system include portable PCsized units, as well as fixed-type system for online monitoring. Application of portable devices for maintenance check, etc. is expected.

New Technologies & Products

[ Figure 5 ] UHF sensor installed [ Figure 4 ]
Sensitivity characteristics for PD detection with a UHF sensor

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[ Figure 6 ] Phase spectra of causes of abnormality

Technology for Monitoring the Vacuum Level of VI
Vacuum circuit breakers (VCB) interrupt the electric current by using the superior arc-extinguishing performance of the vacuum. It is therefore essential to maintain a vacuum at a high level to ensure the performance of the VCB. However, a vacuum interrupter (VI) consists of moving and fixed electrodes, bellows, an insulating envelope, an arc shield, and other components contained in a vacuum container. Since it is difficult to confirm the internal vacuum level of a VI in operation, the levels have been inspected through regular withstand voltage tests. The following paragraphs describe the technology for monitoring the vacuum leakage of a VI, which focuses on the discharge signals occurred at the operating voltage. 4-1 Principle and Sensor for Detecting Vacuum Degradation When the vacuum level drops during VI is closed, discharge will occurr between the electrode and the arc shield. In this case, the electrical potential of the arc shield changes , which is detected by a capacitive coupling sensor shown in Figure 8(7). This principle is

based on Paschen's Law. The example of the relationship between the discharge voltage and the vacuum level (Paschen Curve) is shown in Figure 9. The minimum value of the discharge voltage at around 20Pa is called “Paschen Minimum.” The vacuum level area in which discharge can occur (can be detected) is between 1Pa and 20kPa. Even when the vacuum is at the level at which the discharge may occurr, the detection of a discharge will not immediately cause a serious accident that will deactivate the functions of VCB. This is because the insulation of the VI-to-earth is kept by the gap.

[ Figure 8 ]
Diagram of the principle for detecting vacuum levels

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[ Figure 7 ] Sample system configuration for insulation diagnosis of GIS

However, the interruption operation of the VCB should be avoided as much as possible because it lowers the VI’s current interruption performance. 4-2 Vacuum Monitoring Device Figure 10 is an external view of a vacuummonitoring device that was developed using the principle mentioned above(7). AE Power Systems simplified the configuration and reduced the size of the device to allow it to be housed in the VCB control panel. Generally, the vacuum level decreases by leakage through tiny holes, which may take from several hours to several years. Online monitoring makes it possible to detect vacuum leakage, because it covers the vacuum level area in which discharge is occurred.

Currently, the application of this device is expanding to various models, achieving substantial track record in the field.
New Technologies & Products

Postscript
While many items of substation equipment have outlived the expected design life, the issues are how to make the best use of their performance and how to use them to the limit of their life span. This article described part of the research progress for the technologies for insulation diagnosis and monitoring, which are most important for substation equipment. AE Power Systems will continue its studies to improve the precision of the maintenance data.

[ Figure 9 ]
Relationship between discharge voltage and vacuum level

[ Figure 10 ]
Vacuum monitoring device (prototype)

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References
(1) IEC62478 Ed. 1.0: High-voltage test techniques: Measurement of partial discharge by electromagnetic and acoustic methods, 42/229/DC, 2007 (2) Technical Report in I.E.E. Japan, Henatsuki no shiken, sokutei gijutsu no genjou to sono doukou. No. 816, 2001, p.45-53. (in Japanese) (3) Hatta, Y. et al. Development of partial discharge detector by wavelet transform function with AE sensor. Proceedings of the Fifteenth Annual Conference of Power & Energy Society, I.E.E. Japan, 2004, p.11-19, 11-20. (4) Kato, T. et al. Sensitivity Calibration of UHF Partial Discharge Monitoring System in GIS. I.E.E. Japan Transactions on Power and Energy. vol.122-B, No.11, 2002, p.1226-1231. (5) Shinohara, R. et al. Development of Dipole-Type Partial Discharge Sensor and its application to the GIS. The 2001 Annual Meeting of the I.E.E. Japan, 2001, p.2585. (6) Kato, T. et al. Development of UHF Insulation Diagnosis System of GIS. I.E.E. Japan on Power and Energy. Vol. 119-B, No.4, 1999, p.458-463. (7) Saitoh, H. et al. Discharge-detecting Vacuum-monitoring Device for Vacuum Circuit Breakers. CMD2006. PT-80, 2006.

Authors

Katusnori MIYAGI
Manager Research & Development Management Department Research & Development Division Doctor of Engineering Member of the Institute of Electrical Engineers of Japan

Yujiro YAGI
Deputy General Manager, Business Operation Division General Manager of the Substation Engineering Department Member of the Institute of Electrical Engineers of Japan

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TOPICS
Commercial Operation Starts at 345/138kV GIS S/S in New York City 120kV Dead-Tank Type Vacuum Circuit Breaker

New 72/84kV Dry-Air Insulated Dead-Tank Type Vacuum Circuit Breaker 55kV Two-Pole Live-Tank Type VCB for Railway Substation in China 110/34.5kV Substation Delivered to Saudi Arabia

500kV GIB Mount Type Large-Capacity Transformer

Mobile Transformer Incorporating Hybrid Insulation Technologies Top Transformer Market Share in Dubai

Donation of a Freight Car for Transporting Ultra-Large Power Transformers Participating in the International Symposium on International Standards for Ultra High Voltage

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TOPICS

Commercial Operation Starts at 345/138kV GIS S/S in New York City
Commercial operation of the 345/138kV gas insulated switchgears (GIS), delivered to substation in United States, started in May 2007. This substation is an important primary substation located in Bronx, New York City, and the start of commercial operation was reported on national TV news. AE Power Systems delivered 345kV GIS (8 bays) and 138kV GIS (12 bays). These GIS incorporate the state-of-the-art technologies, which target improved equipment reliability. They apply, for example, a closing method with a resistor to stabilize the voltage of the power network system and are also equipped with highly sensitive partial discharge detectors.

120kV Dead-Tank Type Vacuum Circuit Breaker
AE Power Systems has delivered a 120kV single-break deadtank type vacuum circuit breaker (VCB), the world’s first 120kVclass equipment of its kind, to Kabe Substation of The Chugoku Electric Power Co., Inc. Operation of the VCB was commenced in January 2006. This product applies a vacuum interrupter (VI) that incorporates the latest high-voltage and large-capacity technologies based on AE Power Systems’s accumulated special high-voltage technologies. This VCB also applies an operating system that has an output corresponding to the optimized opening contact travel to improve the breaking performance. The unit also features the optimum combination of components, which enables fully assembled transportation. AE Power Systems will continue its efforts to improve its high-voltage, large-capacity technologies and will expand the lineup of such products.

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New 72/84kV Dry-Air Insulated Dead-Tank Type Vacuum Circuit Breakers
AE Power Systems has developed new 72/84kV dry-air insulated dead-tank type vacuum circuit breakers (VCB) that do not use SF6 gas, which has been designated as a greenhouse gas. The products have been delivered to the United States and Australia. Dry-air insulated dead-tank type VCB uses highly pressurized air inside the tank for insulation. Therefore, conventional units have a larger bellows part for the vacuum interrupter (VI) to allow it to withstand the high pressure. Moreover, the equipment tends to become large because the pressure fluctuation requires higher operating power. In developing the new VCB, AE Power Systems has overcame these issues by applying a dual-pressure system. The units also feature aluminum tanks and covers that do not need painting. What’s more, dry-air is difficult to liquefy even at low temperatures, which allows the VCB to be used at temperatures as low as minus 50 degrees C.

Topics

55kV Two-Pole Live-Tank Type VCB for Railway Substation in China
The 55kV two-pole live-tank type vacuum circuit breaker (VCB), developed by AE Power Systems for a railway substation in China, incorporates the latest vacuum interrupter (VI). This has enabled by reducing the operating power of the operating system to half, allowing a sufficient reduction in vibration generated by the operation, an issue pertaining to the frequent switching operation. In addition, thermal control measures with downsized VI and optimized component layout have enabled to increase the rated current from 1650A to 2000A. Concerning transportation, the height of VCB was made low enough to allow fully assembled shipment by truck in China, which reduced the amount of site installation work.

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TOPICS

110/34.5kV Substation Delivered to Saudi Arabia
These substations are 110/34.5kV primary transmission and distribution facilities located within the site of a huge petrochemical complex under construction in Saudi Arabia. They were delivered and completed in July 2007. The main facilities for these substations include 110/34.5kV, 120MVA and 150MVA main transformers, 20MVA, 3,000kVA, 1,250kVA, 500kVA station service transformers, 34.5kV/13.8kV C-GIS, and 34.5kV GIB. The project was a full-turnkey project of all the construction works for completing the substations, including civil engineering, equipment production, equipment transportation, installation, and testing on site. AE Power Systems brought together all its system technologies and completed two substations in just a 16month period, while meeting the demands special specifications for use in chemical plant, including the explosion-proof construction of the substation buildings and improved reliability of the equipment.

500kV GIB Mount Type Large-Capacity Transformer
The requirements for locating substations and power stations have been becoming increasingly strict in recent years, making it necessary to minimize the installation space of the transformers. AE Power Systems has recently delivered a GIB mount type transformer to the Futtsu Power Station of Tokyo Electric Power Company Inc. for the use at its fourth CCGT plant. This equipment features three threephase 545MVA main transformers installed close to each other in the minimum space, and their 500kV side terminals are taken out in a batch as a common gas insulated busbar (GIB). These are then connected directly to the gas insulated switchgear (GIS) at the transmission end via a CV cable. This has permitted a reduction in the total space required for installation to approximately 70% of that for conventional transformers. To ensure reliability and safety, AE Power Systems has also optimized the configuration and layout of the 500kV GIB and transformers through modeling of the entire equipment and dynamic analysis of the seismic resistance strength.

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Mobile Transformer Incorporating Hybrid Insulation Technologies
Due to the demand for trucks to comply with emission control, mobile transformers to be carried around on trucks are required to have lighter weight, smaller dimensions, and a lower center of gravity. AE Power Systems has manufactured 17MVA mobile transformers that can be loaded on 25ton trucks, which apply hybrid insulation (IEEE and IEC standards have been applied) with high-temperature insulation material (thermal class 220) used in windings. These transformers were manufactured for use at Sunagawa Substation and Kino Substation of Hokkaido Electric Power Co., Inc. The features and specifications of the transformers are : (1) Transformer capacity is 17MVA; (2) Average winding temperature limit over ambient temperature is 95K ; (3) Noise level is lower than 55dB, and; (4) using silicon mold impregnated bushing.

Topics

Top Transformer Market Share in Dubai
Dubai, a member of the United Arab Emirates, has been enjoying rapid economic growth led by international trade, finance, logistics and tourism. This has created a construction boom in Dubai where a large number of mega projects are underway. Demand for electric power is also growing rapidly here and many substations are being constructed every year. AE Power Systems has earned accolades in Dubai, and has been receiving continuous orders for substation equipment since 2002, delivering a large number of transformers (mainly, 132kV 50MVA units) and shunt reactors. AE Power Systems enjoyed a market share of approximately 50% in Dubai during the period from 2002 to 2007, and delivered a total of 56 transformers and reactors in 2007. Cumulative shipments to Dubai will exceed 200 units in 2008.

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Donation of a Freight Car for Transporting Ultra-Large Power Transformers
AE Power Systems has donated a Schnabel type rail car to the Freight Railway Museum at Inabe City, Mie Prefecture in Japan. This rail car, designed to transport a large power transformer weighing up to 130 tons had been stored in the AE Power Systems’s Chiba works. The Freight Railway Museum exhibits various freight cars that were actually used. The museum was established by railway fans in 2003, and has been retained and managed by railway fan volunteers. The Schnabel type rail car applies a special transportation method with the car split into two and the transformer suspended between the two ends of the cars by lifting arms. The car had been used for transporting transformers for 43 years since it was manufactured in 1955. It is representative of large cargo transportation, at one-time, and is the oldest car of its kind that remains in Japan.

Participating in the International Symposium on International Standards for Ultra High Voltage
The International Symposium on International Standards for the Ultra High Voltage (UHV) was held at Beijing in China from July 18 to 22, 2007. This symposium was jointly organized by IEC and CIGRE, and attended by more than 300 participants from China and abroad. What was discussed at this symposium was the adoption of UHV for power transmission system and its international standardization as a response to the growing demand for electrical power on the global level, mainly in BRICs countries. A total of 52 international papers were presented in 11 sessions, and AE Power Systems co-authored seven papers submitted by parties from Japan. The presentations were made by Mr. Yamagiwa, the General Manager of Research & Development Division. What’s more, Chief Engineer Shirasaka from Transformer Business Division worked as a member of the steering committee of this symposium and chaired the transformer session. Reflection of UHV items to the standard of each product is planned to be reviewed in the future.

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Affiliated Company in China

Shandong Luneng AE Power Systems Co., Ltd. (Shandong AE) is located in Jinan city of Shandong Province in China. It is a joint venture corporation among Japan AE Power Systems Corporation, Shandong Luneng Development Group Co., Ltd. – AE Power Systems’s local partner in China, and Fuji Electric Systems Co., Ltd. Shandong AE produces and sells 110kV to 550kV SF6 Gas Insulated Switchgears (GIS) for the China market. The capital of Shandong province, Jinan city, is a beautiful ancient city with a history of 2600 years starting back in the Chunqiu era. Currently, more than 50 Japanese companies are operating in Jinan city. Since its establishment in 1999, Shandong AE has been operating its businesses on the management principle: “Strive for excellence, be diligent in one’s duties, and improve customer satisfaction through competitive and world-leading GIS.” The company has delivered a large number of GIS to power utility companies in China. The products are operating well and their qualities are highly regarded by our customers. Currently, Shandong AE has about 300 employees (including seven Japanese staff members). The employees are thoroughly disciplined under the 5S slogan – Seiri (organization), Seiton (tidiness), Seisou (cleaning and sweeping), Seiketsu (cleanliness), and

Shitsuke (discipline) – and the administrative requirement of strictly adhering to the rules. By maximizing the ability of each employee, Shandong AE has been providing top-level GIS and services to the brisk Chinese market. Shandong AE’s GIS has recently been adopted as power supply facilities for the 2008 Beijing Olympic Games. Thanks to the tremendous economic growth in China, the demand for electric power in the country is increasing rapidly. To satisfy the surging demand for GIS, Shandong AE completed a new building for producing 550kV GIS in 2006, and is expanding its production capacity, with the production of UHV (1,100kV) GIS in view. Shandong AE has also established a new plant for producing molded products such as spacers, one of the major components of GIS, and is enjoying a booming business. Under these circumstances, Shandong AE strives to promote AE Power Systems’s technologies and the AE Power Systems’s brand name in China, and by supplying more GIS, contribute to the development of electricity infrastructure in China.
Takashi FUJI President Shandong Luneng AE Power Systems Co., Ltd.

Corporate Profile
Location Changqing, Jinan, Shandong Province, China Founded May 1999 Capital 1.759 billion yen (as of the end of FY2007) Business descriptions Production and sales of 110kV to 550kV GIS for China market

550kV GIS under impulse test

Opening ceremony of the new building (March, 2007)

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Worldwide Network
8-3, Nishi-Shimbashi 3-chome, Minato-ku, Tokyo, 105-0003, Japan Tel +81-3-5405-3400

Kokubu works

(Hitachi city, Ibaraki-Prefecture) (Ichihara city, Chiba-Prefecture) (Numazu city, Shizuoka-Prefecture)

Chiba works

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Numazu works

3F No.801 Chung Cheng Road, Chung Ho City, Taipei Hsien, Taiwan

7250 McGinnis Ferry Road Suwanee, GA 30024, U.S.A. 16 Collyer Quay, #23-02 Hitachi Tower, Singapore 049318 EJIP Industrial Park Plot 8E, Cikarang Selatan, Bekasi 17550,Indonesia Lot 6, Peringkat 3,Kawasan Perindustrian Alor Gajah 78000 Melaka, Malaysia Luneng Industrial Park Changqing, Jinan, Shandong Prov. 250300, P.R.C.

Premiere Issue
Printed on : July 20, 2008 Published on : August 1, 2008

Editor and Publisher

Kinzo OKAZAKI
Published by

No.1018, He Zuo Road, Jiading Industrial Zone, Shanghai 201821, P.R.C. No.458 CHAO-HONG Road, Suzhou New District Jiangsu 215129, P.R.C.

Japan AE Power Systems Corporation 8-3, Nishi Shimbashi 3-chome, Minatoku, Tokyo, 105-0003, Japan
Phone

+81-3-5405-3400
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< Head Office > 8-3, Nishi-Shimbashi 3-chome, Minato-ku, Tokyo 105-0003 Japan Tel:+81-3-5405-3400 Fax:+81-3-5405-3404


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