WorksheetsAC Motor Additional Revision
Total questions: 15
Worksheet time: 8mins
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
Which of the following is not a recognized type of AC motor?
Synchronous motor
Wound rotor motor
Compound motor
Induction motor
In the photo, the links mean the motor is connected in which configuration?
Shunt
Star
Delta
Series
If a three phase induction motor runs in wrong direction when connected, how can its direction be reversed?
Change the internal wiring of the motor
Interchange all 3 phases
Interchange any two phases
Remove one phase and leave it to run with the other 2 phases
What is meant by the term 'inrush current'?
The current drawn when the motor is under full load
The current drawn initially by the motor when starting
The amount of current that will flow when insulation fails
The currrent drawn by the motor when the load varies saddenly
At what point in an installation should phase rotation be changed?
Motor terminal box
MCC
Contactor
Transformer
