2014 － 2015 学年第 二学期期中考试
34、core 铁芯 35、short ring 短路环 第二版 37、comparator 比较器 39、sensor 传感器 41、object 目的 43
、offset 偏移 45、detector 探测器 47、deviation 偏差 49、reaction 反应，回应
考试方式：闭卷 题 得 号 分 考试时间： 90 分钟 一 二 三 四 卷面总分：100 分 总分 合分人
I vocabulary（共 50 题，每题 0.5 分，共 25 分）
38、closed loop 闭环 40、regulator 调节器 42、confine 限制 44、desired value 期望值 46、controller 控制器 48、transmitter 传感器 50、variable 可变的
1、prime mover 原动机 2、magnetic field 磁场 3.winding 绕 组 4.stator 定 子 5、rotor 转子 6、induced current 感应电流 7、phase 相位 8、exciting voltage 励磁电压 9、iron-loss 铁损 10、power loss 功率损耗 11、leakage flux 漏磁损 12、shunt 分流 13、speed regulation 调速 14、armature current 电枢电流 15、reactive power 无功功率 16、synchronize 同步 17、trip 跳闸开关 18、relay 继电器 19、instrumentation 测试设备 20、optimum 最佳的 21、parameter 参量 22、AVR 自动电压调整器 23.switch 开关 24、circuit breaker 断路器 25. commutator 换向器 26、brusher 机械刷 27、reactor 电抗器 28、resistor 电阻器 29、capacitor 电容器 30、contactor 接触器 31、starting torque 起动转矩 32、slip 滑动 33、inductor motor 作为发动机的感应电动机
II、multiple choice（共 50 题，每题 1 分，共 50 分）
1、 The coil of wire rotating in the magnetic field produces the __C___ .
A. voltage B. power C. current D. frequency 2. The main factor determining
2、 An emergency generator is diesel driven and located __D__.
A. inside of the engine room C. bottom of the steering gear B. top of the bridge house D. outside of the machinery space
3、 The correct statement about the generator?s paralleling off operation is __B____.
A. push the paralleling off button directly B. transfer the load and then perform the paralleling off operation C. push the paralleling off button when the power is nearly zero D. do nothing but just wait for paralleling off B 4、 When you want to stop one generator after parallel operation, the first step is to( ).
第 1 页 共 1 页
A. turn off the engine immediately B. remove the load from the off-going generator C. increase the frequency on the switchboard D. ensure the load is evenly shared 5、 A circuit breaker is ___D___. A. a distribution device switch 6、 The purpose of the reverse power relay, provided on a ship?s service alternator panel, is to trip the circuit in the event of __D____. A. main circuit overload motorization B 7、 Ammeters and voltmeters used in sinusoidal AC power systems indicate which of the following values of the waveforms measured? A. Peak value B.Root-mean-square value. C. Average value. D.Maximum value. B. high power transfer C. generator over-speeding D. alternator B. A lighting equipment C. the indicating instrument D. an isolating
by the settings and characteristics of the __D__. A.voltage regulators B.field theostats C.reverse power relays D.prime mover governors
13、 Prior to starting an AC generator prime mover, the voltage regulator cutout switch should be placed in the__A__. A. manual position B. bus neutral position C. raise voltage position D. transfer position
14、 With a purely resistance load the voltage and current are in phase, giving a power factor of __A__. A. one B. less than one C. more than one D. negative one
15、 Excessive humming of AC contactors may be caused by ___C____. A. burnt arc shields B. shorted armature coils C. a broken shading coil D. high voltage
16、 Insufficient brush pressure on a DC motor may cause ___D____. A. generator overload brushes A 17、 What type of electric motor is most commonly used on board ship? A. Non-synchronous electric motor C. Fully enclosed electric motor B. Synchronous electric motor D. Watertight electric motor B . excess residual magnetism C. water vapor absorption D. sparking of the
8、 In electronic circuitry, the abbreviation ?PCB? commonly means __ _B____. A. pulse coded binary B. printed circuit board C. poly-coated braid D. personal computer bits
9、 If the length of a wire is halved and the cross-sectional area is doubled, the resistance will be __A__. A. quartered(四分之一) B. Unchanged C. doubled D. quadrupled(四倍)
C 18、 How many types of controller action are usually used in control systems? A. Two B. Three C. Four D. Five
19、 The overcurrent relay __C__the motor contractor when the motor exceeds its rated current. A. connects B. Fouls C. trips D. distracts
D 10、 Which of the listed conditions could indicate the need for cleaning electrical insulation? A. Low ambient temperature C. High dielectric strength B. Low operating temperature D. Low megger readings
20、 The __D__ is a measure of the phase difference between voltage and current and is expected as the cosine of phase angle. A. power B. efficiency C. effective power D. power factor
11、 The starting current of a motor is __C___the rated current. A. the same as B. less than C. much larger than D. none of the above
21、 The power factor of an AC generator operating singularly is determined by the __A__. B. prime mover speed C. field excitation D. generators rated voltage
A. connected load 12、 The division of the kilowatt load between two AC generators operating in parallel is controlled
第 2 页 共 2 页
22、 In the event of failure of an auxiliary such as a lubricating pump, the standby pump is started and put on the line automatically. “the line” in this sentence refers to_____B_____. A. fuel manifold B. lubricating pipe line C. auxiliary engine pipe line D. generator output line
glass stem. A. to fall down B. to boil C. to rise up D. to evaporate
31、 When two D.C. generators operate in parallel, they are protected against motorizing
23、 In a pneumatic automation system, a unit producing a signal to govern the position of the by_____D_____. controller of the measured variable, relative to the value of the measured variable, is said to have (B ). A. reset action B. proportional action C. two position action D. rate action A. blow out coils B. governor relay C. under voltage trips D. reverse current trips
32、 The quantity or condition which is measured and controlled is known as the(A ). A. controlled variable B. manipulated variable C. set point D. control point
24、 If a DC motor runs hot, the cause may be ___C____. A. high mica condition B. low ambient temperature D. an open in the shunt field
33、 To repaire small electrical motor that has been submerged in saltwater, you should __A__. A. wash it with fresh water and apply an external source of heat B. renew the windings
C. send it ashore to an approved service facility 25、 A motor speed regulator maintains the motor speed at a ___A____value despite variations in D. rinse all electrical parts with a carbon tetrachloride(四氯化碳)cleaning solvent and then blow dry load torque. A. constant B. change C. Appropriate D. accurately the motor with compressed air 34、 You are attempting to parallel two AC generators and the synchroscope pointer is revolving
C. clogged ventilation ducts
26、 In a three-phase, open-delta connected transformer, the line current is equal to ____A___. in the slow direction. This indicates that the frequency of the incoming machine is __B__. A. the phase current B. three times the phase current D. the difference of any two phase current A. higher than the bus frequency B. lower than the bus frequency C. the same as the bus frequency but out of phase with it D. the same as the bus frequency, and the circuit breaker may be closed at any pointer position 35、 When two different metals are joined to form a closed circuit and exposed to different temperatures at their junctions __A__ which can be used to measure temperature. A. a current will flow B. a heat will flow C. a power will develop D. a pressure will produce
C. the sum of any two phase currents
27、 The main switchboard is made up of following parts except ___C___. A. bus-bar B. paralleling panel C. shore power box D. machinery panel of the main generator
B 28、 The first requirement for logical troubleshooting of any system is the ability to ____. A. collect all available data on a casualty B. recognize normal operation D. isolate the faulty component
C. identify the probable cause of a symptom
C 29、 What type of rotor is used in split-phase motors? A. Drum. B. Salient pole (凸极). C. Squirrel-cage (鼠笼式). D. Wound-rotor.
36、 When the current in a power transmission line is increased, the power loss _A______. A. increases as the square of the current current 第 3 页 共 3 页 B. decreases as the square root of the current D. increases in direct proportion as the
30、 A increase in temperature causes the liquid in a Glass thermometer___C___ in the narrow
C. remains the same, as it is independent of current flow
A 37、 Which of the listed devices is used to measure pressure and convert it to an electrical signal? 44、 The instantaneous reduction in voltage of an A C generator, resulting from an increase in A. Transducer(传感器). B.Reducer(减压器). C. Transformer（变压器）. D.Rectifier(整流器). load, and prior to the automatic voltage regulator correcting the situation, is called voltage( C). B. Drop C. dip D. regulation
38、 A diesel generator has just been paralleled with an AC turbo-generator, but the load can not A. droop be properly divided. This could be caused by(A ). A. an incorrect diesel generator governor speed droop adjustment B. a faulty reverse power relay within the main circuit breaker assembly C. unsynchronized isochronous load distribution adjustments D. a different speed setting on each unit 39、 A constant output voltage from an AC generator is maintained by the __C__. A.prime mover governor B.exciter generator 40、 Remote control means that ___C___. A. the system is manned manually B. the system is controlled automatically D. all the above C.voltage regulator D.reverse power relay __D____.
45、 The unit of electrical power is the __C__. A.ampere B.kilovolt C.watt D.farad(法拉)
46、 Loss of or weak residual magnetism in an alternator or generator can be corrected for by
A. running the rotor in the opposite direction for 5 minutes B. allowing the generator to run at 10% of normal speed for 5 minutes C. running the generator at normal speed with the field rheostat fully counterclockwise D. using a storage battery or battery charger to ?flash? the field 47、 A mode of control, whereby the speed of motion of the final control element is linearly proportional to the deviation of the controlled variable from set point, is called __ B__.
C. the system is situated remotely from the operator 41、 A feedback is an input(D ).
A. which governs the state of a variable variable
B. which provides a visual and audible alarm D. which measures the state of the controlled
A. rate control
B. derivative control
C. two position control
D. integral control
C. which indicates values of controlled variables
48、 ____D____of the emergency generator at a low voltage value is usual on modern installations. A. Manually start up B. Automatic stop C. Automatic paralleling D. Automatic start up
C 42、 For lubricating oil cooling controller, which statement is right? A. The three way by-pass valve in the oil line controlled from a sensor at the outlet from the engine controls the cooling. B. This valve should be fail-safe with all the oil going through the cooler. C. Most the filters are placed after the coolers. D. Temperature monitoring would be carried out on the common inlet temperature, thrust inlet temperature, and blower outlet temperatures, most having alarms for high temperature. A 43、 Which of the following detectors will you choose for detecting smoke from fire? A. Ionization type B. Thermometer C. Thermocouple D. Strain gauge
C 49、 The insulation of electric generators during short idle periods should be _______. A. allowed to cool slowly to ambient temperatures B. flashed with direct current to remove any residual magnetism C. kept warm by using strip or space heaters D. relieved of all capacitive charge by grounding the conductors 50、 The load sharing characteristics of two diesel generators operating in parallel are mostly dependent on their governor __D__. A. load limit settings B. idle speed settings C. speed limit settings D. speed droop settings
第 4 页 共 4 页
得分 Ⅲ、Reading（共 4 题，每题 2.5 分，共 10 分）
Circuit breakers must be capable of making an breaking under normal conditions and also abnormal conditions such as short circuit. As the circuit breaker must be able to withstand closing onto a fault conditions without sustaining damage, it is of heavy construction. Fitted with an over current release and overloads with time lags, a circuit breaker can be used as follows: to control the output of a generator , as a direct on-line starter and control outgoing feeder circuits. On modern switchboards, “ draw out” circuit breakers may be fitted. In the open position the whole circuit breaker can be wound clear of the bus bars, thus full inspection and maintenance can be achieved without the necessity of de-energizing the bus bars. The “plug in” contacts joining the circuit breaker to the bus bars are not capable of taking before any attempt is made to withdraw it. A mechanical interlock is fitted arranged to trip the circuit breaker before the winding handle can be inserted. The breaker also has a mid position. In this position the control circuits are still connected with the bus bar connection isolated. The electrical operation of the breaker can then be tested. Circuit breakers are normally fitted with under voltage protection and tripping is accomplished by shorting, which releases the latching in mechanism. The no-volt coil may also be open circuited by a reverse power relay and an overload trip fitted with a time delay. 1. A circuit breaker can be used as follows except ___C_____. A. to control outgoing feeder circuits B. to act as a direct on line starter C. to take the breaking load on line D. to control the output of a generator
2. A “draw out” circuit breaker refers to a circuit breaker ____A____. A. which can be made clear of the bus bars by using a winding handle B. which can be made clear of the bus bars by plugging in contacts C. whose test can be carried out with the control circuit still connected D. whose test can be carried out with the bus bar connection isolated 3. A mechanical interlock is fitted ____B_____. A. to take the breaking load when the circuit breaker is being withdrawn B. to put the circuit breaker, before being withdrawn, in the open position C. to put the circuit breaker, before being withdrawn, in the mid position D. to take the breaking load when the contacts join the circuit breaker to the bus bars 4. According to this passage, the electrical operation of this kind of circuit breaker can be tested when _____D____. A. the control circuits are connected B. the bus bar connection is isolated C. either A or B D. both A and B IV、Translation（共 3 题，每题 5 分，共 15 分） 1.Any deviation between the desired and actual drum level and any deviation between feed and steam flow will result in controller action to adjust the feed water control valve.
2. Electrical motors applied in agriculture eliminated human and animal
muscle power from such tasks as handling grains or pumping water.
3. More number of generators are used to facilitate load sharing
and to prevent wear down due to excessive load.
第 5 页 共 5 页
第 6 页 共 6 页