AC Motor Additional Revision

When installing an AC motor, why is it important to align the rotor shaft up correctly?

• Reduce lateral loads and premature failure of the bearings

• Reduce stator imbalance

• The motor will only require two bolts in the mounting feet

• It will allow maintenance to be schedules to be lengthened

In an application where high starting torque is required, what would be the best type of AC motor to be used?

• Star connected three phase motor

• Synchronous three phase motor

• Delta connected three phase induction motor

• Capacitor start, single phase motor

On a three phase induction motor, what is meant by the term 'slip'?

• The difference between the synchronous speed and the actual motor

• The motors ability to change speed quickly

• The type of motor coupling

• How the motor is fastened to the bedplate

The photo shows the end plate from a single phase motor with a switch fitted. How is the switch used in the operation of the motor?

• To give over current protection

• To indicate when full speed has been achieved

• To open circuit the start winding after start up

• To cut the motor supply if it over speeds

In the photo, the links mean the motor is connected in which configuration?

• Capacitor run

• Capacitor start

• Star

• Delta

The photo shows a 3 phase motor name plate, what does the item identified relate to?

• The motor power factor

• The motors maintenance schedule

• The internal motor impedance

• Minimum acceptable insulation resistance value

State what the abbreviation DOL means with regard to electrical motors.

• Direct over load

• Drop out lock

• Drawn on line

• Direct on line

In an AC motor, when the current flow increases, the magnetic field....

• fluctuates

• decreases

• stay the same

• increases

Which of the following is not a recognized part of a 3 phase induction motor?

• rotor

• fan

• stator

• armature

A typical system for the starting of large motors is which of the following?

• Delta

• Delta/Star

• Star

• Star/Delta