Alternator MCQ | Synchronous Generator MCQ

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

1. almost zero lagging
2. unity
3. about 0.6 lagging
4. None of these

132. Alternators are classified into

1. Salient pole & non-salient pole
2. Slip-ring & squirrel cage
3. Self-starting & separately starting
4. 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

1. Synchronous reactance
2. Transient reactance
3. Sub transient reactance
4. None of these

134. Alternators are rated at

1. kW
2. kVA
3. kVA or kW
4. kWh

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

1. Increased
2. Decreased
3. Increased or decreased
4. Kept same

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

1. Short circuit characteristic and open circuit characteristic
2. Open circuit characteristic and armature impedance
3. Armature impedance
4. 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

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

138. An alternator has

1. Rotating armature and stationary field
2. Stationary armature and stationary field
3. Rotating armature and rotating field
4. Stationary armature and rotating field

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

1. (Vector sum of induced emf per coil) x (Arithmetic sum of induced emf per coil)
2. (Vector sum of induced emf per coil)/(Arithmetic sum of induced emf per coil)
3. (Vector sum of induced emf per coil)+(Arithmetic sum of induced emf per coil)
4. (Vector sum of induced emf per coil)−(Arithmetic sum of induced emf per coil)

140. Damper windings are provided to

1. Prevent hunting in synchronous motors and provide starting torque in generators
2. Prevent hunting in generators and provide starting torque in synchronous motors
3. Provide starting torque in synchronous motors and generators
4. Prevent hunting in both generators and synchronous motors