AC Motors Revision

1. Which item below determined the frequency of maintenance for AC motors?

• Size of supply cables

• Stability of motor

• Use of motor

• The frequency of supply power

1. Chose the item in below which is the first to be identify prior to dismantling the motor.

• Location of motor eye bolt

• Location of nameplate

• Location of stator

• Location of power supply source

1. An AC motor is an electric motor driven by an -------------.

• Direct current

• Armature

• Alternate current.

• Both alternate and Direct current

Starters are used in induction motor because………..?

• Its starting torque is high

• It is run against heavy load

• It cannot run in reverse direction

• It reduce the inrush current

1. We should use IP washer to maintain the IP rating of terminal box when glanding

• True

• False

The starting torque of an indication motor is maximum when

• Rotor resistance equals rotor reactance

• Rotor resistance is twice the rotor reactance

• Rotor resistance is half the rotor reactance.

• Rotor resistance is R₂ times the rotor reactance.

In which area the motor rotation be changed?

• Stator

• Rotor

• Terminal Box

• Capacitor

The speed of AC motor when not connected to the Load is provided by ?

• Frequency

• Frequency and current

• Number of poles and frequency

• Number of poles and voltage

To increase starting torque in some AC motors

• The rotor bars are angled.

• The supplied current increase

• The Supplied Voltage increase

• The stator windings segregate

With increase of load, the speed of induction motor operating in the stable region is…………?

• Increases and then becomes constant

• Remains constant

• Decreases

• Increase