EXAMINATION : GENERATOR

1. When paralleling two alternators they must have:
 All of the mentioned alternatives. (Same number of phases, Same phase rotation,& Same         frequency).

2. You have just syncronized 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?
Raise the governor speed controller of the incoming alternator and reduce the governor speed controller of the alternator already on 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?
Trip/stop all non essential loads that are connected to the switchboard

4. At which point do you engage the main circuit breaker of the incoming alternator when paralleling two alternators?
With the pointer of the synchronoscope at 0° (12 O'clock) and both synchronizing lamps dark (off)

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?
The alternators are not generating the same voltages and should be adjusted on automatic voltage regulator rheostats

6. With two alternators running in parallel, you wish to stop one. The first step is to:
Remove the load from the alternator to be stopped

7. You are paralleling two alternators and the pionter of the synchronoscope slowly stops rotating and remains stopped in one position before the circuit breaker is closed. This would indicate:
The frequency of the incoming alternator is the same as that of the main switchboard

8. 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:
10 000 000 Ohms

9. 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?
Improve material of intake air filters

10. On routine daily inspection you notice that there is a light arching between an alternator's carbon brushes and rotor sliprings, with alternator operating at 70% load. Should you:
Check the surface of the sliprings, polish if necessary and bed in the brushes

11. What is the purpose of the alternator reverse power trip?
To prevent the alternator from "motoring" by being supplied  power from other parallel alternator

12. If you alter the field excitation voltage of one alternator operating in parallel, this will cause change in that alternators:
Reactive load (kVAR)

13. What determines the power factor of an alternator when it is connected singularily to the switchboard?
The load connected to the switchboard

14. The automatic voltage regulator is used to control the output voltage of the alternator at varying load conditions by:
Varying the excitation field strength by regulating excitation voltage/current

15. The power requirements for the excitation winding/circuit for a 3-phase alternator operating at rated output power are supplied by:
The alternators output itself via the automatic voltage regulator

16. A 450 volt 3 phase brushless alternator will have the following combination of items mounted on the rotor:
3 phase excitation winding/rectifier bank/main field winding

17. A three phase alternator is connected singularily 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?
579.2 kw

18. 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:
Completetly loose its share of the load causing the auxilliary engine to speed up

19. 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:
Prevent damage to sensitive electronic components from high voltage tester

20. 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?
(Y)