Induction Motor Quiz

If a 4-pole 50 Hz 3-phase induction motor run at 1440 rpm, then value of slip is

• 0.04%

• 3.30%

• 4.00%

• 6.00%

The power scale of circle diagram of an induction motor can be found from

• stator resistance test

• no-load test only

• short-circuit test only

• Stator resistance and No load test

When the rotor of 3 phase induction motor is blocked, the value of slip will be

• 0

• 0.1

• 0.3

• unity

When the rotor of three phase induction motor is blocked, its rotor induced emf is

• 0

• minimum

• unity

• maximum

When the rotor of a three phase induction motor is blocked its rotor frequency will become

• 0

• half of supply frequency

• equal to supply frequency

• very high

In a capacitor start induction motor, the capacitor is connected in series with

• starting winding

• running winding

• main winding

• compensating winding

With the increase in supply voltage, the starting torque of a 3 phase induction motor

• increases

• decreases

• remains same

• remains constant

When a three-phase alternator supplies capacitive load, armature reaction flux will be

• Opposing the main magnectic field

• Helping the main magnetic field

• Either (a) or (b)

• zero

For a short pitch coil, the pitch factor is

• Less than 1

• Equal to 1

• More than 1

• Zero

If the speed of an alternator is reduced by half, its generated emf will become

• double

• same

• half

• one fourth