Synchronous Generator Objectives part 01
01 . In an alternator, voltage drops occur in armature resistance, leakage reactance and armature reaction.
02 . The magnitude of various voltage drops that occur in an alternator, depends on load current.
03 . In an alternator, at lagging power factor, the generated voltage per phase, as compared to that at unity power factor must be more than the terminal voltage
04 . The power factor of an alternator depends on Load.
05 . Which kind of rotor is most suitable for turbo alternators which are designed to run at high speed ? Non-salient pole type
06 . Salient poles are generally used on low and medium speed prime movers.
07 . The frequency of voltage generated in an alternator depends on number of poles and rotative speed.
08 . The frequency of voltage generated by an alternator having 8 poles and rotating at 250 rpm is 16 2/3 Hz.
09 . An alternator is generating power at 210 V per phase while running at 1500 rpm. If the need of the alternator drops to 1000 rpm, the generated voltage per phase will be 140 V.
10 . A 10 pole AC generator rotates at 1200 rpm. The frequency of AC voltage in cycles per second will be 100
11 . The number of electrical degrees passed through in one revolution of a six pole synchronous alternator is 1080
12 . Fleming’s left hand rule may be applied to an electric generator to find out direction of induced emf
13 . If the input to the prime mover of an alternator is kept constant but the excitation is changed, then the reactive component of the output is changed
14 . An alternator is said to be over excited when it is operating at lagging power factor
15 . When an alternator is running on no load the power supplied by the prime mover is mainly consumed to meet all no load losses
16 . As the speed of an alternator increases the frequency increases
17 . For an alternator when the power factor of the load is unity the armature flux will be cross-magnetising
18 . The driving power from the prime mover driving the alternator is lost but the alternator remains connected to the supply network and the field supply also remains on. The alternator will behave as a synchronous motor and will rotate in the same direction
19 . If the input of the prime mover of an alternator is kept constant but the excitation is changed, then the reactive component of the output is changed
20 . For 50 Hz system the maximum speed of an alternator can be 3000 rpm.