1. A stationary alternator should not be connected to a live bus bar because it ?

will get short-circuited

will disturb generated e.m.fs. of other alternators connected in parallel

is likely to run as a synchronous motor

will decrease but-bar voltage though momentarily

Answer: will get short-circuited

Explanation:


2. If the steam supply of an alternator running in parallel with another identical alternator is increased keeping its excitation constant, then ?

it will supply greater portion of the load

the power factor would be decreased

it would over-run the other alternator

its rotor will fallback in phase with respect to the other machine

Answer: it will supply greater portion of the load

Explanation:


3. Which of the following is the common synchronous speed in r.p.m. between 50 Hz and be 60 Hz alternators ?

200

300

600

900

Answer: 600

Explanation:


4. Which of the following coils in an alternator will have e.m.f closer to sine waveform ?

Distributed winding in full pitch coils

Distributed winding in short pitch coils

Concentrated winding in full pitch coils

Concentrated winding in short pitch coils

Answer: Distributed winding in short pitch coils

Explanation:


5. An alternator running in parallel with other alternators all having automatic voltage regulators is to be taken off the bus. The usual procedure before opening the switch is to ?

reduce the power fed to the prime mover

reduce alternator excitation

increase alternator excitation

none of the above

Answer: reduce the power fed to the prime mover

Explanation:


6. In an alternator the armature reaction is mainly influenced by ?

the power factor of the load

short-circuit ratio

speed of the alternator

total current drawn

Answer: the power factor of the load

Explanation:


7. What kind of rotor is most suitable for turbo-alternators which are designed to run at high speed ?

Salient pole type

Non-salient pole type

Either (a) or (b)

None of the above

Answer: Non-salient pole type

Explanation:


8. The frequency of voltage generated in large alternators is ?

50 Hz

60 Hz

in kilo cycles

in mega cycles

Answer: 50 Hz

Explanation:


9. Fleming's left hand rule may be applied to an electric generator to find out direction of ?

magnetic field

induced e.m.f,

rotor rotation

none of the above

Answer: induced e.m.f,

Explanation:


10. The choice of field construction, in an alternator, is basically determined by ?

generated voltage needed by the customers

comparative cost of the field systems

supply frequency required by the consumers

the kind of energy source available in the geographic location

Answer: the kind of energy source available in the geographic location

Explanation: