单选题To increase the frequency of an operating AC generator, you should （）Aincrease the field excitationBdecrease the field excitationCincrease the number of magnetic polesDincrease the speed of the prime mover
单选题
To increase the frequency of an operating AC generator, you should （）
A
increase the field excitation
B
decrease the field excitation
C
increase the number of magnetic poles
D
increase the speed of the prime mover
参考解析
解析：
暂无解析
相关考题：
You are attempting to parallel two AC.generators, and the synchroscope pointer revolving in the fast direction.This indicates that the frequency of the incoming machine is A.higher than the bus equencyB.lower than the bus equencyC.the same as the bus frequency but out of phase with itD.same as the bus frequency and the circuit breaker may be closed at
You are attempting to parallel two AC generators and the synchroscope pointer is revolving in the slow direction. This indicates that the frequency of the incoming machine isA.higher than the bus frequencyB.lower than the bus frequencyC.file same as file bus frequency but out of phase with itD.the same as the bus frequency, and the circuit breaker may be closed at nay pointer position
The frequency of an AC generator is controlled by the ___.A.rheostatB.governorC.exciterD.capacitor
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
If you know that the vessel you are about to call on the VHF radio maintains a radio watch on both the working and the calling frequencies, which frequency should you call on ?______.A.Calling frequencyB.Distress frequencyC.Urgency frequencyD.Working frequency
Users are performing a large volume of inserts and deletes on the application tables in the APPS tablespace. You observe that there are several warning alerts being generated for the APPS tablespace space usage metrics. Currently， the warning threshold for the tablespace space usage metrics is set to 70%. To make the generated alerts more useful as a problem identification tool， you want to reduce the frequency of alert generation for the tablespace space usage metrics for the APPS tablespace. What should you do？（）A、disable SQL tracing for theAPPS tablespaceB、disable logging attribute for the APPS tablespaceC、modify the tablespace to be a dictionarymanaged tablespaceD、increase the critical threshold value for the tablespace space usage metrics for the APPS tablespaceE、increase the warning threshold value for the tablespace space usage metrics for the APPS tablespace
You find that the database performance degrades while you backup the PROD database using Recovery Manager （RMAN）. The PROD database is running in shared server mode. The database instance is currently using 60% of total operating system memory. You suspect the shared pool fragmentation to be the reason. Which action would you consider to overcome the performance degradation？（）A、Configure Java Pool to cache the java objects.B、Configure Streams Pool to enable parallel processing.C、Increase Shared Pool size to cache more PL/SQL objects.D、Increase Database Buffer Cache size to increase cache hits.E、Configure Large Pool to be used by RMAN and shared server.F、Increase the total System Global Area （SGA） size to increase memory hits.
You work as a database administrator for Certkiller .com. You find that the database performance degrades while you backup the Certkiller database using Recovery Manager （RMAN）. The Certkiller database is running in shared server mode. The database instance is currently using 60% of total operating system memory. You suspect the shared pool fragmentation to be the reason. Which action would you consider to overcome the performance degradation？（）A、Configure Java Pool to cache the java objects.B、Configure Streams Pool to enable parallel processing.C、Increase Shared Pool size to cache more PL/SQL objects.D、Increase Database Buffer Cache size to increase cache hits.E、Configure Large Pool to be used by RMAN and shared server.F、Increase the total System Global Area （SGA） size to increase memory hits.
单选题The purpose of DC generator brushes is to （）.Aneutralize armature reactionBconduct electric current to an outside circuitCconvert DC current to AC currentDprovide excitation to a DC generator
单选题If you know that the vessel you are about to call on the VHF radio maintains a radio watch on both the working and the calling frequencies，which frequency should you call on? （）ACalling frequencyBDistress frequencyCUrgency frequencyDWorking frequency
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 （）ArotorBstatorCexciterDarmature
单选题Excessive vibration in an operating diesel generator may be caused by （）Aelectrical overloadBsurging at governed RPMCloose engine mounting boltsDcoolant leaking into the cylinder
单选题A probable cause for a turbo generator tripping out on overspeed is a sudden（）Aloss of field excitationBtotal loss of loadClarge increase in loadDloss of steam pressure
单选题The instantaneous reduction in voltage of an AC generator, resulting from an increase in load, and prior to the automatic voltage regulator correcting the situation, is called voltage （）.AdroopBdropCdipDregulation
单选题The power factor of an AC generator operating singularly is determined by the （）Aconnected loadBprime mover speedCfield excitationDgenerators rated voltage
单选题When securing an AC generator, you should FIRST （）.Aopen the generator circuit breakerBswitch the voltage regulator to “manual”Cdecrease the field excitation to minimumDreduce the load on the unit
单选题When it is accepted to remain on the frequency indicated，you should say（）.AStanding by on VHF frequencyBComing to VHF frequencyCVHF frequency. is the best place for you to stay byDremaining in frequency. and do not change
单选题The frequency of an AC generator is controlled by the （）ArheostatBgovernorCexciterDcapacitor
单选题The frequency output of an operating alternator is controlled by the （）.Arelative speed of the rotor polesBnumber of turns of wire in the armature coilCstrength of the magnets usedDoutput voltage
单选题You are attempting to increase the checkpoint interval on your database. Each of the following choices will affect the duration and/or frequency of checkpoints, except one. Which is it?（）ASize of redo logs BNumber of datafiles CLOG_CHECKPOINT_INTERVAL DLOG_CHECKPOINT_TIMEOUT
单选题The frequency of an AC generator is adjusted by means of the （）Amain alternator field rheostatBexciter field rheostatCprime mover governor controlDequalizing reactor
单选题The frequency of the alternating current generated by a synchronous generator is governed by the speed and the（）Afull excitationBloadCpower factorDnumber of poles
单选题The purpose of the commutator and brushes on a DC generator is to（）Achange AC to DCcurrentBchange DC to AC currentCneutralize a armature reactionDcarry current to the outside circuit
单选题An increase in the load on a turbocharged diesel engine operating at constant speed will result in an increase in （）AexhaustBair box pressureCbrake main effective pressureDall of the above
单选题You are attempting to parallel two AC generators, and the syncope pointer is revolving in the fast directionThis indicates that the frequency of the incoming machine is （）.Ahigher than the bus frequencyBlower than the bus frequencyCthe same as the bus frequency but out of phase with itDthe same as the bus frequency and the circuit breaker may be closed at any pointer position
单选题When paralleling two AC generators, the frequency of the machine coming on-line, immediately prior to closing its breaker, should be （）Aslightly less than the oncoming generator frequencyBthe same as the bus frequencyCslightly greater than the bus frequencyDthe same as the bus voltage