SYNCHRONOUS GENERATOR

In an alternator, voltage drops occurs in

• (A) armature resistance only

• (B) armature resistance and leakage reactance

• (C) armature resistance, leakage reactance and armature reaction

• (D) armature resistance, leakage reactance, armature reaction and earth connections.

The magnitude of various voltage drops that occur in an alternator, depends on

• (A) power factor of the load

• (B) load current

• (C) power factor x load current

• (D) power factor x (load current)2.

The power factor of an alternator depends on

• (A) Load

• (B) Speed of rotor

• (C) Core losses

• (D) Armature losses.

Which kind of rotor is most suitable for turbo alternators which arc designed to run at high speed ?

• (A) Salient pole type

• (B) Non-salient pole type

• (C) Both (A) and (B) above

• (D) None of the above.

Salient poles are generally used on

• (A) high speed prime movers only

• (B) medium speed prime movers only

• (C) low speed prime movers only

• ( D) low and medium speed prime movers.

The frequency of voltage generated in an alternator depends on

• (A) number of poles

• (B) rotative speed

• (C) number of poles and rotative speed

• (D) number of poles, rotative speed and type of winding.

The frequency of voltage generated by an alternator having 8 poles and rotating at 300 rpm is

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

• (A) reactive component of the output is changed

• (B) active component of the output is changed

• (C) power factor of the load remains constant

• (D) power factor of the load reduces.

An alternator is said to be over excited when it is operating at

• (A) unity power factor

• (B) leading power factor

• (C) lagging power factor

• (D) lagging to leading power factor.

When an alternator is running on no load the power supplied by the prime mover is mainly consumed

• (A) to meet iron losses

• (B) to meet copper losses

• (C) to meet all no load losses

• (D) to produce induced emf in armature winding.