ECET EEE 2011-1

 

1. In synchronous motor, minimum armature current corresponds to

A. lagging power factor
B. zero power factor
C. unity power factor
D. leading power factor

Answer : unity power factor
Explanation:-

2. The angle between the synchronously rotating stator flux and rotor poles of a synchronous motor is known as

A. torque angle
B. power factor angle
C. slip angle
D. synchronous angle

Answer : synchronous angle
Explanation:-

3. An electric motor is which both the rotor and stator fileds rotate at same speed is called

A. DC motor
B. universal motor
C. induction motor
D. synchronous motor

Answer : synchronous motor
Explanation:-

4. Breather of a transformer has

A. sand
B. mercury
C. silica gel
D. salt

Answer : silica gel
Explanation:-

5. During resistance welding the heat produced at the joints proportional to

A. current
B. voltage
C. I^2 R
D. Volt-amperes

Answer : I^2 R
Explanation:-

6. The maximum starting torque of a 3-phase induction motor is obtained when the rotor resistance is

A. equal to the rotor reactance
B. double that of the rotor reactance
C. 1.5 times of the rotor reactance
D. very small and rotor reactance is large

Answer : equal to the rotor reactance
Explanation:-

7. The motor usually used for driving refrigerator

A. DC Shunt motor
B. universal motor
C. Capacitor start induction motor
D. plain squirrel cage induction motor

Answer : Capacitor start induction motor
Explanation:-

8. The motor, which is not slef starting is

A. induction motor with high slip
B. induction motor with medium slip
C. shaded pole motor
D. synchronous motor

Answer : synchronous motor
Explanation:-

9. Skewing of rotor slots in induction motor is to

A. reduce the magnetic hum of rotor
B. increase the efficiency
C. increase the distribution factor
D. reduce the synchronous speed

Answer : increase the distribution factor
Explanation:-

10. P2:Pcu:Pm is equal to

A. 1:1-S:S
B. 1:S:(1-S)
C. S:1:1-S
D. 1-S:S:1

Answer : 1:S:(1-S)
Explanation:-