AC Motor Drives_2

Main advantage of an ac motor as compared to a DC motor is

• less maintenance

• expensive

• can work in any environment

• controllability

Which of the following is the advantage of double squirrel cage rotor as compared to the round bar cage rotor?

• Large slip

• Lower starting torque

• Higher efficiency

• Higher power factor

The advantages of a group driver electric drive are

• High efficiency

• Low Noise

• Constant speed

The starting torque of a squirrel-cage induction motor is

• Full-load torque

• Slightly more than full-load torque

• Low

• Negligible

A 50 Hz, 3-phase induction motor has a full load speed of 1440 r.p.m. The number of poles in the motor is

• 2 pole

• 4 pole

• 6 pole

• 8 pole

Which of the following motor has high starting torque?

• Slip ring Induction motor

• Squirrel cage induction motor

No load test of 3-phase induction motor used to determine

• Variable loss

• Constant loss

• Eddy current loss only

• Hysteresis loss only

Introducing the external resistance increases

(i) speed

(ii) output power

(iii) starting torque

• (iii)

• (ii),(iii)

• (ii)

• (i), (ii), (iii)

The maximum EMF is induced in the rotor of a 3-phase induction motor when it

• No-load

• Full-load

• Half-load

• rotor is blocked

Which type of braking can be used for saving energy?

• dynamic

• plugging

• regenerative