01. No load test of 3-phase induction motor used to determine
Variable loss
Constant loss
Eddy current loss only
Hysteresis loss only
02. Blocked rotor test in an induction motor is used to determine
Leakage impedance
Copper loss
Both a & b
None of the above
03. Which of the following losses are negligible in blocked rotor test?
Mechanical losses
Iron losses
Both a & b
None of the above
04. In induction generator operation the slip is always
Positive
Negative
Infinite
Zero
05. In an induction motor if the air gap is increased than which of the following statement is correct
Power factor will decrease
Power factor will increase
Speed will increase
Speed will decrease
06. If the applied rated voltage per phase is reduced to one-half, then the starting torque of squirrel cage induction motor becomes
4 times the initial value
2 times the initial value
1/4 of the initial value
1/2 times the initial value
07. The value of power factor of an induction motor operating at no load is
0.9 lagging
Unity
0.2 lead
0.2 lag
08. what is the ratio of rotor input power to rotor copper loss in an induction motor?
1/(1 – S)
1 – S
1/S
S
09. Semi closed slots or totally closed slots are used in induction motors to improve
Starting current
Starting Torque
Power Factor
Pull-out Torque
10. The rotor slots are slightly skewed in squirrel cage induction motor in order to
Increasing Rotor bar strength
Prevent cogging effect
Both 1 & 2
None of the above
11. If an induction machine is run at above the synchronous speed it acts as
Synchronous Motor
Synchronous Generator
Induction Generator
None of the above
12. The best method to increase the starting torque of a 3-phase slip ring induction motor is
Rotor Resistance
Supply voltage
Supply Frequency
None of the above
13. A small air gap in 3 phase induction motor helps to
Reduce cogging effect
Reduce Crawling effect
Reduce Magnetizing effect
All of the above
14. Induction motors have the advantage of
Less Maintenace
Less cost
Simple in construction
All of the above
15. The rotor power output of a 3-phase induction motor is 30 KW and corresponding slip is 4%. The rotor copper loss will be
625 Watt
250 Watt
1000 Watt
1250 Watt
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