网友您好， 请在下方输入框内输入要搜索的题目：
题目内容
（请给出正确答案）
单选题
The power factor of an AC generator operating singularly is determined by the （）
A
connected load
B
prime mover speed
C
field excitation
D
generators rated voltage
参考答案
参考解析
解析：
暂无解析
更多 “单选题The power factor of an AC generator operating singularly is determined by the （）A connected loadB prime mover speedC field excitationD generators rated voltage” 相关考题
考题
When voltage and current developed in an AC circuit reach their peak values at the same time, the power factor is _____.A.laggingB.leadingC.maximumD.minimum
考题
The frequency of an AC generator is controlled by theA.rheostatB.governorC.exciterD.capacitor
考题
The frequency of an AC generator is controlled by the ___.A.rheostatB.governorC.exciterD.capacitor
考题
The power factor of an AC generator operating singularly is determined by the_______ .A.connected loadB.prime mover speedC.field excitationD.generator's rated voltage
考题
材料：The field current supply in older machines comes from a lower voltage direct current generator or exciter on the same shaft as the alternator. Modern machines however are either statically excited or of the high-speed brush-less type. The exciter is required to operate to counter the effects of power factor for a given load. The power factor is a measure of the phase difference between voltage and current and is expressed as the cosine of the phase angle. With a purely resistance load the voltage and the current are in phase, giving a power factor of one. The power consumed is therefore the product of voltage and current. Inductive or capacitive loads, combined with resistance loads, produce lagging or leading power factors which have a value less than one.The power consumed is therefore the product of current, voltage and power factor. The alternating current generator supplying a load has a voltage drop resulting from the load. When the load has a lagging power factor this voltage drop is considerable. Therefore the exciter, in maintaining the alternator voltage, must vary with load current and also the power factor. The speed change of the prime mover must also be taken into account.问题： The word “machines” in the passage refers to _____.A.the direct current generatorB.the alternating current generatorC.the exciterD.the prime moverWhich of the following statements is true according to the passage ?A.With a purely resistance load, the power factor is zeroB.Inductive loads combined with resistance loads produces leading power factorsC.Capacitive loads combined with resistance loads produces lagging power factorsD.With a purely resistance load, the phase angle is zeroWhen the load has a lagging power factor this voltage drop is considerable. This sentence means that _____.A.with a purely resistance load, the voltage drops too muchB.there is a considerable voltage drop in the capacitive load combined with resistance loadC.when the load is the capacitive load combined with resistance load, the voltage drops to zeroD.when the load is the inductive load combined with resistance load, the voltage drop is fairly largeThe exciter must vary with: ① load current ② the power factor, ③ speed change of the prime mover.A.①B.②C.①②D.①②③请帮忙给出每个问题的正确答案和分析，谢谢！
考题
A laptop operates on battery power when connected with an AC adapter. Once the battery discharges, the computer turns off and will not turn back on. Which of the following are the MOST likely causes of the laptop issue? （）(Select TWO).A、The LCD monitor’s power inverter does not function properly.B、The operating system’s power settings prevent the battery from charging.C、The battery is not compatible with the laptop.D、The internal power connection on the motherboard is faulty.E、The power adapter is not working.
考题
单选题The purpose of DC generator brushes is to （）.A
neutralize armature reactionB
conduct electric current to an outside circuitC
convert DC current to AC currentD
provide excitation to a DC generator
考题
单选题A DC generator is used to supply direct current in order to maintain an AC generator field and is known as a/an （）A
rotorB
statorC
exciterD
armature
考题
单选题Excessive vibration in an operating diesel generator may be caused by （）A
electrical overloadB
surging at governed RPMC
loose engine mounting boltsD
coolant leaking into the cylinder
考题
单选题The division of the kilowatt load between two AC generators operating in parallel is controlled by the settings and characteristics of the （）.A
voltage regulatorsB
field rheostatsC
reverse power relaysD
prime mover governors
考题
单选题The load between two steam-driven alternators operating in parallel may be adjusted by varying （）A
the speed of the alternatorsB
the field strength of the machinesC
the power factor of the alternatorsD
steam supply to the prime movers
考题
单选题The power factor of an AC generator operating singularly is determined by the （）A
connected loadB
prime mover speedC
field excitationD
generators rated voltage
考题
单选题The power factor at which a paralleled AC generator operates is usually adjusted by the （）.A
connected loadB
prime mover speedC
field excitationD
generators rated voltage
考题
单选题When voltage and current developed in an AC circuit reach their peak values at the same time, the power factor is （）A
laggingB
leadingC
maximumD
minimum
考题
单选题When securing an AC generator, you should FIRST （）.A
open the generator circuit breakerB
switch the voltage regulator to “manual”C
decrease the field excitation to minimumD
reduce the load on the unit
考题
单选题The frequency of an AC generator is controlled by the （）A
rheostatB
governorC
exciterD
capacitor
考题
单选题To increase the frequency of an operating AC generator, you should （）A
increase the field excitationB
decrease the field excitationC
increase the number of magnetic polesD
increase the speed of the prime mover
考题
单选题Most often （） is attached to the engine-propeller shaft for efficient electric power generation.A
a variable-speed AC generatorB
a fixed-speed AC generatorC
an air blowerD
a DC generator
考题
单选题Emergency generator is installed on board mainly to （）A
connect to the busbar when the load increasingB
supply power specially to charging panelC
be put into operation during the ship arriving at or leaving portD
ensure the power supply to critical equipment after the main switchboard out of power
考题
单选题Why is it desirable to operate paralleled AC generators at the same power factor?（）A
Circulating currents are kept to a minimumB
Field excitation losses are kept to a minimumC
Generator rotors will have a lesser tendency to huntD
Because a power factor increase will decrease kilowatt output
考题
单选题The alternating current generator supplying a load has a voltage drop resulted from the loadWhen the load has a lagging power factor this voltage drop （）.A
is smallB
may be neglectedC
is usefulD
is considerable
考题
多选题A laptop operates on battery power when connected with an AC adapter. Once the battery discharges, the computer turns off and will not turn back on. Which of the following are the MOST likely causes of the laptop issue? （）(Select TWO).AThe LCD monitor’s power inverter does not function properly.BThe operating system’s power settings prevent the battery from charging.CThe battery is not compatible with the laptop.DThe internal power connection on the motherboard is faulty.EThe power adapter is not working.
考题
单选题A diesel generator has just been paralleled with an AC turbo-generator, but the load can not be properly divided.This could be caused by（）A
an incorrect diesel generator governor speed droop adjustmentB
a faulty reverse power relay within the main circuit breaker assemblyC
unsynchronized isochronous load distribution adjustmentsD
a different speed setting on each unit
考题
单选题To （） , the power is supplied by main switchboard directly not though sub-board.A
save network costB
improve the reliability of supplying power to important loadC
prevent sequence reverseD
increase the power factor of important load
考题
单选题To equalize the power factor of two alternators operating in parallel, the （）A
field excitation of both units is adjustedB
governors of both units are adjustedC
phase sequence is alteredD
kilowatt load is evenly divided
考题
单选题A constant output voltage from an AC generator is maintained by the （）.A
prime mover governorB
exciter generatorC
voltage regulatorD
reverse power relay
热门标签
最新试卷