THREE PHASE INDUCTION MOTORS QUIZ

Zero frequency

The same frequency as the slip frequency

The same phase as the rotor e.m.f.

High value for the satisfactory speed control

Has simple and rugged construction

Provides high starting torque

Provides fine speed control

None of the listed here

Star-delta starting

Direct on line

By auto transformer starting

None of the listed here

Lower winding is more effective

Lower cage winding has low reactance

Outer cage winding has good pf

None of the listed here

Magnitude of supply voltage

Supply frequency

Phase sequence of supply voltage

Number of poles

K × torque with direct switching

k2/torque with direct switching

K2 × torque with direct switching

k/torque with direct switching

Rotating

None of the listed here

Steady

Alternating

Copper loss will reduce

Bearing friction will reduce

Windage losses will be more

The power factor will be low

None of the listed here

It requires less maintenance

It is inexpensive

External resistance can be inserted in the rotor circuit

The motor will run at reduced speed

The motor will not run

The motor will run in reverse direction

The motor will burn