Alternator Quiz

When the speed of an alternator increases

• The frequency decrease

• The frequency increases

• The frequency remains same

• The frequency changes

In alternators the standard practice, now a days is to have

• Rotating field

• Rotating armature

• Both A & B

• Static Field

In an alternator, the armature reaction will be completely magnetizing in case the load power factor is

• Zero lagging

• Zero leading

• 0.866

• Unity

In an alternator the voltage generated per phase is proportional to

• Number of turns in coil

• stator current

• rotor current

• stator resistance

An alternator is capable of delivering power at a particular efficiency. The frequency can be increased by

• Reversing the armature rotation

• Reversing the field polarity

• Increasing the current supplied to the field electromagnets

• Increasing the armature speed

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

Regulation of an alternator supplying resistive or inductive load is

• Always negative

• Always positive

• Both Positive and Negative

• zero

In an alternator short pitch coils are used

• To reduce the stray losses

• To reduce the size of the machine

• To provide accurate phase difference of 1200 between

• To reduce the harmonics in generated e.m.f.

In an alternator terminal voltage rise will be more

• When leading load is thrown off

• When lagging load is thrown off

• When unity power factor load is thrown off

• No change in load

If the input to the prime mover of an alternator is kept constant but the excitation is increased, then

• kVA will be lagging

• >kVA will be leading

• >kVA will be changed

• The power factor of the load remains constant