WorksheetsEMJ43003 AC MOTOR
Total questions: 18
Worksheet time: 7mins
Which part of an induction motor is responsible for producing the rotating magnetic field?
ROTOR
STATOR
SHAFT
COMMUTATOR
What is the main fucntion of the rotor in an induction motor?
To supply electrical power
To create a magnetic field
To rotate and deliver mechanical output
To control speed
Which type of current is supplied to the stator of a three-phase induction motor?
What is the phenomenon called when the rotor speed is less than the synchronous speed?
SLIP
SKEW
LAG
HOLDING
Which loss is primarily responsible for heating in the core of an AC motor?
Copper loss
Iron loss
Friction loss
Windage loss
What is the typical range of slip in a normal running induction motor?
0–1%
2–8%
10–20%
20–30%
What is the main difference between a synchronous and an induction motor?
Synchronous motors require slip to operate
Induction motors run at synchronous speed
Synchronous motors run at synchronous speed
Induction motors use DC supply
Which component is NOT present in a squirrel cage induction motor?
Stator
Rotor
Brushes
Shaft
What is the effect of increasing the load on an induction motor?
Decreases slip
Increases slip
No effect on slip
Stops the motor
What is the main reason for skewing the rotor bars in a squirrel cage induction motor?
To increase speed
To reduce noise and vibration
To increase torque
To reduce losses
What is the synchronous speed of a 6-pole, 50 Hz induction motor?
750 rpm
1000 rpm
1500 rpm
3000 rpm
Which factor does NOT affect the synchronous speed of an AC motor?
Number of poles
Supply frequency
Load on the motor
Type of winding
Which of the following is NOT a method to control the speed of an induction motor?
Changing supply frequency
Changing number of poles
Varying supply voltage
Changing rotor resistance in squirrel cage motors
What is the main difference between a squirrel cage and a slip ring rotor?
Squirrel cage has windings
Slip ring allows external resistance
Squirrel cage uses slip rings
Slip ring has no windings
What is slip speed in an induction motor?
The difference between stator and rotor resistance
The difference between synchronous speed and rotor speed
The sum of stator and rotor speed
The ratio of stator to rotor current
If the rotor turns at synchronous speed, what is the slip?
0
0.5
1
0.2
If the rotor is stationary, what is the slip?
0
7%
100%
2%
4- pole Induction motor with frequency 60 Hz running with a speed of 1740 rpm. Calculate the % slip .
30%
9.6%
3%
96%
