1、When paralleling two alternators they must have:
A、All of the mentioned alternatives.
B、Same number of phases.
C、Same phase rotation.
D、Same frequency.
2、You have just synchronized a second alternator onto the main switchboard, and want to equally share the load between the 'on' and incoming alternators. What would you do first?
A、Lower the governor speed controller of the incoming alternator and increase the governor speed controller of the alternator already on the switchboard.
B、Trip the circuit breaker of the incoming alternator and check the voltage and speed adjustments before trying again.
C、Raise the governor speed controller of the incoming alternator and reduce the governor speed controller of the alternator already on the switchboard.
D、Adjust voltage rheostat for the incoming alternator on the front of the switchboard.
3、With two alternators operating in parallel at 75% load capacity, one trips without any warning. What is the first action that should be taken?
A、Restart the tripped alternator immediately.
B、Start and connect the emergency alternator.
C、Trip/stop all nonessential loads that are connected to the switchboard.
D、Check the circuit breaker of the tripped alternator.
4、At which point do you engage the main circuit breaker of the incoming alternator when paralleling two alternators?
A、With the pointer of the synchronoscope at 0(12 O'clock) and both synchronizing lamps dark (off).
B、With the pointer of the synchronizer stopped at any position and both synchronizing lamps bright (on).
C、With the pointer of the synchronoscope rotating fast and both synchronizing lamps flashing on and off.
D、In none of the mentioned alternatives.
5、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?
A、The alternators are not generating the same voltages and should be adjusted on automatic voltage regulator rheostats.
B、Alternator frequencies are different and should be adjusted on the governor speed controllers.
C、Alternators are out of phase and should be tripped and paralleled again.
D、One alternator has lost one of its phases.
6、With two alternators running in parallel, you wish to stop one. The first step is to:
A、Remove the load from the alternator to be stopped.
B、Make sure the load is evenly shared.
C、Trip the main circuit breaker.
D、Increase the frequency on the switchboard.
7、You are paralleling two alternators and the pointer of the synchronoscope slowly stops rotating and remains stopped in one position before the circuit breaker is closed. This would indicate:
A、The voltage of the incoming alternator is the same as that of the main switchboard.
B、The incoming alternator is in phase with the switchboard, but the frequency is not the same.
C、The frequency of the incoming alternator is the same as that of the main switchboard.
D、The synchronoscope is not functioning properly and should be checked.
9、A 450 volt, 859 kW rated generator has not been in operation for several weeks. Prior to starting, insulation resistance readings are taken. The minimum acceptable insulation resistance reading on the main stator winding to allow you to proceed with running the generator is:
A、1000 Ohms.
B、10000 Ohms.
C、10000000 Ohms.
D、10 Ohms.
10、On regular inspections of alternator windings it is found that windings are always covered with a heavy oil film coming from the atmosphere surrounding the auxiliary engine. After cleaning with an approved solvent, what do you do?
A、Take no additional action.
B、Blank off intake air filters.
C、Reinsulated the windings after each cleaning.
D、Improve material of intake air filters.
11、On routine daily inspection you notice that there is a light arching between an alternator's carbon brushes and rotor slip rings, with alternator operating at 70% load. Should you:
A、Reverse the polarity of the excitation voltage at the brush holder connection.
B、Move the position of the brushes around the slip rings to find the correct neutral position.
C、Check the surface of the slip rings, polish if necessary and bed in the brushes.
D、Increase the tension on the brushes.
12、What is the purpose of the alternator reverse power trip?
A、To prevent the alternator from being paralleled if it is out of phase with the main switchboard.
B、To give automatic disconnection of the circuit breaker when you are taking the alternator off the switchboard.
C、To prevent the alternator from 'motoring' by being supplied power from other parallel alternator.
D、To prevent parallel operation if the excitation field voltage is reversed.
13、If you alter the field excitation voltage of one alternator operating in parallel, this will cause change in that alternators:
A、Reactive load (KVAR).
B、Active load (kW).
C、Frequency.
D、None of the mentioned alternatives.
14、What determines the power factor of an alternator when it is connected singularity to the switchboard?
A、The generated voltage.
B、The excitation voltage.
C、Number of pairs of pole coils in the excitation winding.
D、The load connected to the switchboard.
15、The automatic voltage regulator is used to control the output voltage of the alternator at varying load conditions by:
A、Supplying variable current to compounding and no load transformers in the alternator stator winding circuit.
B、Varying the excitation field strength by regulating excitation voltage/current.
C、Regulating the voltage signal to the engine governor to regulate the speed to the desired load condition.
D、All of the mentioned alternatives.
16、The power requirements for the excitation winding/circuit for a 3-phase alternator operating at rated output power are supplied by:
A、Independent power supply and rectifier unit.
B、The main switchboard via a three phase rectifier.
C、The alternators output itself via the automatic voltage regulator.
D、Independent battery supply.
17、A 450 volt 3 phase brushless alternator will have the following combination of items mounted on the rotor:
A、3 phase excitation winding/rectifier bank/main field winding.
B、3 phase excitation winding/ main field winding.
C、Excitation field winding/rectifier bank/main field winding.
D、Excitation field winding/main field winding.
18、A three phase alternator is connected singularity to the main switchboard. The switchboard instruments show 440 Volts/950 amperes. With a power factor of 0.8 what will be the kW load?
A、522.5 kW.
B、905 kW.
C、579.2 kW.
D、334.4 kW.
19、Due to failure of one of the carbon brushes the excitation voltage is lost on one alternator that is operating in parallel. Will that alternator then:
A、Completely loose its share of the load causing the auxiliary engine to speed up.
B、Overload due to reduced voltage output and increased current.
C、Continue to share the active load (kW) but have very high reactive load (KVAR).
D、Try to take all the load and so trip the main circuit breaker.
20、Before taking insulation resistance readings of generator windings the automatic voltage regulators should be isolated and all semiconductor short circuited or disconnected in order to:
A、Prevent damage to sensitive electronic components from high voltage tester.
B、Protect insulation resistance tester from being damaged.
C、Prevent charging of capacitive components within the automatic voltage regulator causing false regulation when generator restarts.
D、Prevent operation of automatic voltage regulator during insulation testing.
21、When 3 phase alternators are operating in parallel, it is very important that the reactive load is evenly shared so that the total alternator loads are evenly shared. If the total alternator load is the vector sum of active and reactive loads, which side of the vector diagram shown represents the reactive load?
A、Either (X) or (Y).
B、(Y).
C、(X).
D、None of the mentioned alternatives.
联系客服
