1. The disadvantage of star delta starting of three phase induction motor is that:
a) during starting power loss are increased
b) the starting torque increases as the motor runs with jerks
c) the starting torque will be one third of that in case of delta connection
d) at the time of chage over between star to delta a voltage peak is produce that may cause damage to the
insulation
2. In case of 3 phase slip ring induction motor as the rotor resistance is increased, the starting torque:
a) increases
b) decreases
c) increases upto certain value with increase in resistance and then remains constant
d) increases up to certain value with increase in resistance and then decreases
3. In V/f speed control of 3 phase induction motor, the maximum torque and slip at which the maximum torque occurs , would respectively:
a) increase and decrease
b) increase and increase
c) decrease and increase
d) decrease and decrease
4. The speed of the induction motor depends on:
a) number of the stator poles
b) supply frequency
c) supply stator voltage
d) all the above
5. Star-delta starting is equivalent to auto transformer starting with __ tapping:
a) 33.3%
b) 50%
c) 57.7%
d) 83%
6. When the supply voltage to an induction motor id reduced by 10%, the maximum torque will decrease by approximately:
a) 5%
b) 10%
c) 20%
d) 40%
7. The deep bar of double cage rotor are employed to:
a) increase starting torque
b) improve efficiency
c) increase pull out torque
d) reduce rotor core loss
8. Which of the following ac motor is widely used:
a) Squirrel cage induction motor
b) Slip-ring induction motor
c) Double cage induction motor
d) Synchronous motor
9. Cogging in an induction motor occurs when,
a) number of stator teeth - number of rotor teeth = odd number
b) number of stator teeth - number of rotor teeth = even number
c) number of stator teeth - number of rotor teeth = 0
d) number of stator teeth - number of rotor teeth = negative number
10. Skew of the rotor bar eliminates:
a) the effect of space harmonics
b) the effect of crawling
c) magnetic noise
d) vibrations
a) during starting power loss are increased
b) the starting torque increases as the motor runs with jerks
c) the starting torque will be one third of that in case of delta connection
d) at the time of chage over between star to delta a voltage peak is produce that may cause damage to the
insulation
2. In case of 3 phase slip ring induction motor as the rotor resistance is increased, the starting torque:
a) increases
b) decreases
c) increases upto certain value with increase in resistance and then remains constant
d) increases up to certain value with increase in resistance and then decreases
3. In V/f speed control of 3 phase induction motor, the maximum torque and slip at which the maximum torque occurs , would respectively:
a) increase and decrease
b) increase and increase
c) decrease and increase
d) decrease and decrease
4. The speed of the induction motor depends on:
a) number of the stator poles
b) supply frequency
c) supply stator voltage
d) all the above
5. Star-delta starting is equivalent to auto transformer starting with __ tapping:
a) 33.3%
b) 50%
c) 57.7%
d) 83%
6. When the supply voltage to an induction motor id reduced by 10%, the maximum torque will decrease by approximately:
a) 5%
b) 10%
c) 20%
d) 40%
7. The deep bar of double cage rotor are employed to:
a) increase starting torque
b) improve efficiency
c) increase pull out torque
d) reduce rotor core loss
8. Which of the following ac motor is widely used:
a) Squirrel cage induction motor
b) Slip-ring induction motor
c) Double cage induction motor
d) Synchronous motor
9. Cogging in an induction motor occurs when,
a) number of stator teeth - number of rotor teeth = odd number
b) number of stator teeth - number of rotor teeth = even number
c) number of stator teeth - number of rotor teeth = 0
d) number of stator teeth - number of rotor teeth = negative number
10. Skew of the rotor bar eliminates:
a) the effect of space harmonics
b) the effect of crawling
c) magnetic noise
d) vibrations
