AC Machines

Which three of the following are types of three-phase rotor?

• Axial cage

• Dual cage

• Extended rotor

• Squirrel cage

• Wound rotor

A three-phase squirrel cage induction motor will produce maximum torque when:

• The shape of the rotor is maximised for the greatest torque

• Motor resistance is at a maximum

• Rotor resistance equals rotor reactance

• Rotor reactance is at a maximum

Complete this sentence - As the load on an induction motor increases:

• both the efficiency and the power factor increase.

• efficiency increases but power factor decreases.

• efficiency decreases but power factor increases.

• both the efficiency and the power factor decrease.

Which two of the following characteristics of a split-phase motor can be used to identify it?

• High starting torque

• Two dissimilar windings

• Low starting current

• Three-phase power supply

Which motor has a starting winding with high resistance and low reactance?

• Washing machine motor

• Ceiling fan motor

• Air compressor motor

• Refrigerator motor

Which motor is known for the best starting and running torque?

• Capacitor start/capacitor run

• Permanently split capacitor motor

• Shaded Pole

• Universal motor

Which single phase motor is commonly used to drive an industrial floor polisher?

• Capacitor start/capacitor run

• Permanently split capacitor motor

• Shaded Pole

• Universal motor

Which motor type is typically used for applications requiring low starting torque?

• Capacitor start/capacitor run

• Permanently split capacitor motor

• Shaded Pole

• Universal motor

Which motor type is often used in small fans and blowers?

• Capacitor start/capacitor run

• Permanently split capacitor motor

• Shaded Pole

• Universal motor

Which motor type is most suitable for applications requiring high speed and low torque?

• Capacitor start/capacitor run

• Permanently split capacitor motor

• Shaded Pole

• Universal motor