1. When the load power factor is unity, the effect of armature reaction on the main field flux of an alternator is
- no effect
2. By matching which of the following individual machines, the load frequency control is achieved?
- Reactive power
- Turbine inputs
- Generated voltage
- Turbine and generator ratings
3. At lagging loads, the effect of armature reaction in an alternator is?
4. Magnetic field poles are the ________ part of an alternator.
5. Variable losses in alternator is determined by
- iron losses
- iron losses + armature losses
- armature losses + series field losses
- iron losses + mechanical losses
6. If a P-pole alternator rotates N completes rotations, it produces __________ cycles of generated voltage. (As N in the number of rotations made per second)
7. A 400 MVA, 20 kV synchronous generator has 0.3 per unit. synchronous reactance. The per unit synchronous reactance on the base values of 200 MVA and 40 kV is
- 2.2 p.u.
- 2.7 p.u.
- 2.6 p.u.
- 2.4 p.u.
8. Which one of the following is not a necessary condition to be satisfied for synchronizing an incoming alternator to an already operating alternator?
- Same voltage
- Same frequency
- Same prime mover speed
- Same phase sequence
9. A 200 MVA, 11kV, 3-phase, 6-pole synchronous generator has an inertia constant H equal to 2 MJ/MVA. What will be the magnitude of storage energy at synchronous speed?
- 200 MJ
- 100 MJ
- 2 MJ
- 400 MJ
10. In a 360 kV network, 280 kV is recorded at a 360 kV bus. The reactive power absorbed by a shunt rated for 50 MVAR, 360 kV connected at the bus is
- 40.8 MVAR
- 30.24 MVAR
- 33.67 MVAR
- 41.55 MVAR
11. When an alternator is running on no-load the power supplied by the prime mover is mainly consumed to
- produce induced emf in the armature winding
- meet iron losses
- meet copper losses
- meet all no-load losses
12. An alternator is said to be over-excited when it is operating at
- unity power factor
- leading power factor
- lagging power factor
- lagging to leading power factor
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
- the active component of the output is changed
- the power factor of the load remains constant
- the power factor of the load reduces
14. Fleming’s left-hand rule may be applied to an electric generator to find out
- the direction of rotor rotation
- the polarity of induced emf
- the direction of induced emf
- the direction of the magnetic field
15. The number of electrical degrees passed through in one revolution of a six-pole synchronous alternator is
16. A 10 pole AC generator rotates at 1200 rpm. The frequency of AC voltage in cycles per second will be
17. An alternator is generating power at 210 V per phase while running at 1500 rpm. If the need for the alternator drops to 1000 rpm, the generated voltage per phase will be
- 180 V
- 150 V
- 140 V
- 105 V
18. The frequency of voltage generated in an alternator depends on
- number of poles
- rotative speed
- number of poles and rotative speed
- number of poles, rotative speed, and type of winding
19. Salient poles are generally used on
- High-speed prime movers only
- Medium speed prime movers only
- Low-speed prime movers only
- Low and medium speed prime movers
20. Which kind of rotor is most suitable for turbo alternators which are designed to run at high speed?
- Salient pole type
- Non-salient pole type
- Both (a) and (b) above
- None of the above