131. Under short circuit conditions, the power factor of an alternator is

- almost zero lagging
- unity
- about 0.6 lagging
- None of these

132. Alternators are classified into

- Salient pole & non-salient pole
- Slip-ring & squirrel cage
- Self-starting & separately starting
- None of these

133. If a 3 phase alternator is short-circuited at its terminal, then the initial value of short circuit current will be limited by

- Synchronous reactance
- Transient reactance
- Sub transient reactance
- None of these

134. Alternators are rated at

- kW
- kVA
- kVA or kW
- kWh

135. To reduce the peripheral speed of an alternator, the diameter of the rotor is

- Increased
- Decreased
- Increased or decreased
- Kept same

136. To determine voltage alternator the following experimental results are required

- Short circuit characteristic and open circuit characteristic
- Open circuit characteristic and armature impedance
- Armature impedance
- Short circuit characteristic and open circuit characteristic and Armature impedance

137. During the operation of a connecting a busbar in parallel with an incoming alternator the

- Terminal voltage and speed of the incoming alternator should be same as that of busbar but the phase can be different.
- Terminal voltage and phase of the incoming alternator should be same as that of the busbar but the speed can be different.
- Terminal voltage, speed and phase of the incoming alternator need not be same as that of the busbar.
- Terminal voltage, speed and phase of the incoming alternator should be same as that of the busbar.

138. An alternator has

- Rotating armature and stationary field
- Stationary armature and stationary field
- Rotating armature and rotating field
- Stationary armature and rotating field

139. The pitch factor or chording factor of a short pitch winding in an alternator is defined as

- (Vector sum of induced emf per coil) x (Arithmetic sum of induced emf per coil)
- (Vector sum of induced emf per coil)/(Arithmetic sum of induced emf per coil)
- (Vector sum of induced emf per coil)+(Arithmetic sum of induced emf per coil)
- (Vector sum of induced emf per coil)−(Arithmetic sum of induced emf per coil)

140. Damper windings are provided to

- Prevent hunting in synchronous motors and provide starting torque in generators
- Prevent hunting in generators and provide starting torque in synchronous motors
- Provide starting torque in synchronous motors and generators
- Prevent hunting in both generators and synchronous motors