单选题An alternator switchboard has a synchroscope and synchronizing lamps, if the synchroscope is broken, which of the steps listed is the most essential before an alternator can be paralleled with the bus （）AThe breaker should be closed when one synchronizing lamp is dark and the other is brightBThe breaker should be closed when both synchronizing lamps are brightCThe frequency meter should be used to determine that the incoming alternator frequency is slightly higher than the busDA portable phase sequence indicator must be used to verify the information from the lamps
单选题
An alternator switchboard has a synchroscope and synchronizing lamps, if the synchroscope is broken, which of the steps listed is the most essential before an alternator can be paralleled with the bus （）
A
The breaker should be closed when one synchronizing lamp is dark and the other is bright
B
The breaker should be closed when both synchronizing lamps are bright
C
The frequency meter should be used to determine that the incoming alternator frequency is slightly higher than the bus
D
A portable phase sequence indicator must be used to verify the information from the lamps
参考解析
解析：
暂无解析
相关考题：
any pointer positionDue to failure of one of the carbon brushes the excitation voltage is lost on one alternator that operating in parallel.Then that alternator will() A.completely loose its share of the load causing the auxiliary engine to speed up.B.overload due to reduced voltage output and increased currentC.continue to share the active load(kw)but have high very reactive loadD.try to take all the load and so trip the main circuit breaker
Where could you monitor the correct instant for synchronizing without aid of synchroscope or synchronizing lamp? A.Distribution boardB.Section boardC.Emergency switchboardD.Main switchboard
An alternator is being paralleled with one on the line At the instant the circuit breaker is close, the frequency of the incoming alternator will normallyA.increaseB.not changeC.decreaseD.be exactly 60 hertz
单选题（）is not installed on the emergency switchboard.AAmmeter and changeover switchBSpeed governor deviceCSynchroscopeDWattmeter
单选题With No~1 and No~2 alternators running in parallel and the KW loads equally shared, one alternator is drawing much higher current than the other.What does this indicate?（）AThe alternators are not generating the same voltages and should be adjusted on automatic voltage regulator rheostatsBAlternator frequencies are different and should be adjusted on the governor speed controllersCAlternators are out of phase and should be tripped and paralleled againDOne alternator has lost one of its phases
单选题The frequency of an alternator is controlled from the main switchboard by adjusting the（）Afrequency meterBvoltage regulatorCgovernor controlDsychroscope switch
单选题An indicator on the main switchboard should show （） the emergency battery is in service or not.AthatBwhenCifDwhether
单选题A switchboard, for a AC electrical distribution system, will be provided with which of the following components （）.AFrequency meterBAmmeterCVoltmeterDAll of the above
单选题（） is a machine by which electrical energy is transformed into mechanical energy.AAn alternatorBAn electric motorCA diesel engineDA main switchboard
单选题（）is not a part of the main switchboard.ABusbarBLoad panel of main generatorCParalleling panelDShore connection box
单选题（）is power supplied by main switchboard directly not through sub-board.ADeck machineryBLittle power loadCSome important loadDstationary submersible pump
单选题The purpose of a main switchboard circuit breakers reverse-power trip is to （）.Aprevent main circuit overloadBprotect the circuit breaker blowout coilCprevent alternator motorizationDprevent low voltage tripout
单选题（）is not installed on the emergency switchboard.AControl panelBParalleling panelCLoad panelDBusbar
单选题（）is a function of the reactive / resistive characteristics of the load items and cannot be adjusted by manipulating the alternator control devices.APower factorBPower ratioCcompression ratioDCompression factor
单选题The frequency of an alternator at a given RPM is determined by the （）.Anumber of turns of wire in the armature coilBnumber of magnetic polesCstrength of the magnets usedDoutput voltage
单选题The correct phase rotation of a three-phase alternator can be checked with a（）AdynamometerBpower factor meterCthree-phase motorDpolyphase voltmeter
单选题A switchboard for an AC electrical system requires the use of which of the following devices（）.AFrequency meterBOhmmeterCInduction voltage regulatorDCurrent transformer governor
单选题The separate supplies are connected in either star or delta formationThe star formation is most commonly used and requires（） slip-rings on the alternator.AtwoBthreeCfourDfive