1. Hydro-Generators are generally employed to run at:
a) 500 rpm
b) 1000 rpm
c) 1500 rpm
d) 3000 rpm
2. In synchronous machine the stator frame serves the purpose of:
a) Holding the armature stampings in position and also in circulating cold water for cooling
b) insulating the armature windings
c) providing path to magnetic flux
d) providing the field winding
3. The stator core of the synchronous machine is laminated so as to reduce:
a) eddy current loss
b) hysteresis loss
c) both hysteresis loss and eddy current loss
d) copper loss
4. In a large synchronous generators, the damper windings are provided in order to reduce:
a) increase stability
b) reduce frequency fluctuations
c) reduce voltage fluctuations
d) both (a) and (c)
5. Smooth cylindrical rotors are usually designed for:
a) 2 or 4 pole
b) 8 pole
c) 12 pole
d) 24 pole
6. The rotor preffered for low speed hydro-generator is:
a) salient pole rotor
b) non salient pole rotor
c) wound rotor
d) none of the above
7. In an alternator short circuit current is limited by:
a) saturated synchronous impedance
b) unsaturated synchronous impedance
c) either of the above
d) none of the above
8. Unbalanced 3 phase stator currents cause:
a) vibrations
b) heating of the rotor
c) double frequency currents in the rotor
d) all the above
9. The armature reaction effect influences the:
a) operating speed
b) windage loss
c) generator voltage per phase
d) both (a) and (c)
Three phase alternators are always connected in star connection because of:
a) reduce the size of stator conductors used
b) increase the terminal voltage
c) reduce the magnetic losses
d) all the above
a) 500 rpm
b) 1000 rpm
c) 1500 rpm
d) 3000 rpm
2. In synchronous machine the stator frame serves the purpose of:
a) Holding the armature stampings in position and also in circulating cold water for cooling
b) insulating the armature windings
c) providing path to magnetic flux
d) providing the field winding
3. The stator core of the synchronous machine is laminated so as to reduce:
a) eddy current loss
b) hysteresis loss
c) both hysteresis loss and eddy current loss
d) copper loss
4. In a large synchronous generators, the damper windings are provided in order to reduce:
a) increase stability
b) reduce frequency fluctuations
c) reduce voltage fluctuations
d) both (a) and (c)
5. Smooth cylindrical rotors are usually designed for:
a) 2 or 4 pole
b) 8 pole
c) 12 pole
d) 24 pole
6. The rotor preffered for low speed hydro-generator is:
a) salient pole rotor
b) non salient pole rotor
c) wound rotor
d) none of the above
7. In an alternator short circuit current is limited by:
a) saturated synchronous impedance
b) unsaturated synchronous impedance
c) either of the above
d) none of the above
8. Unbalanced 3 phase stator currents cause:
a) vibrations
b) heating of the rotor
c) double frequency currents in the rotor
d) all the above
9. The armature reaction effect influences the:
a) operating speed
b) windage loss
c) generator voltage per phase
d) both (a) and (c)
Three phase alternators are always connected in star connection because of:
a) reduce the size of stator conductors used
b) increase the terminal voltage
c) reduce the magnetic losses
d) all the above
