Electrical Machines-II Quiz

For a Three phase induction motor, when the rotor is blocked the slip =?

• 1

• 3

• 4

• 2

The stator of a 3 phase induction motor has six slots per pole per phase. what is the total number of stator poles produced?

• 12

• 6

• 3

• 18

In a split phase motor, the running winding should have

• (a) high resistance and low inductance

• (b) low resistance and high inductance

• (c) high resistance as well as high inductance

• (d) low resistance as well as low inductiance

If the capacitor of a single-phase motor is short-circuited

• (a) the motor will not start

• (c) the motor will run in reverse direction

• (b) the motor will run

• (d) the motor will run in the same direction at reduced r.p.m.

In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to

• (a) improve power factor

• (b) increase overload capacity

• (c) reduce fluctuations in torque

• (d) to improve torque

In a split phase motor

• (a) the starting winding is connected through a centrifugal switch

• (b) the running winding is connected through a centrifugal switch

• (c) both starting and running windings are connected through a centrifugal switch

• (d) centrifugal switch is used to control supply voltage

Which of the following is NOT true of parallel operation of Alternator

• Increases in Reliability

• Increase in Losses

• Increase in efficiency

• proper load sharing

Alternators are usually designated to generate which type of AC voltage?

• with fixed frequency

• with variable frequency

• fixed current

• fixed power factor

In Synchronous machines, the salient poles are

• rotating field winding

• stationery field winding

• rotating armature winding

• stationery armature winding

The Two methods of Synchronising an alternator are ?

• Loading effect and phase sequence

• Lamp method and synchroscope method

• Two Bright and one dark lamp method

• Hysteresis loss and friction loss method