Em-ii Mcq.docx

MCQ; Electrical Machine-II; B.Tech 4th EE 1. In an alternator, voltage drops occurs in (A) Armature resistance only (B) Armature resistance and leakage reactance

(C) Armature resistance, leakage reactance and armature reaction

(D) Armature resistance, leakage reactance, armature reaction and earth connections. 2. In an alternator, at lagging power factor, the generated voltage per phase, as compared to that at unity power factor (A) Must be same as terminal voltage

(C) Must be more than the terminal voltage

(B) Must be less than the terminal voltage

(D) Must be 1.41 time the terminal voltage.

3. The frequency of voltage generated in an alternator depends on (A) Number of poles

(C) Number of poles and rotating speed

(B) Rotating speed

(D) Number of poles, rotating speed and type of winding.

4. Synchronous motor can operate at (A) Lagging power factor only

(C) Unity power factor only

(B) Leading power factor only

(D) Lagging, leading and unity power factor only. 5. In case the field of a synchronous motor is under excited, the power factor will be (A) Leading

(C) Zero

(B) Lagging

(D) Unity.

6. A synchronous motor is switched on to supply with its field windings shorted on themselves. It will (A) Not start

(C) Start as an induction motor

(B) Start and continue to run as an (D) Bum immediately. Synchronous motor 7. The damping winding in a synchronous motor is generally used (A) To provide starting torque only

(C) To reduce eddy currents

(B) To reduce noise level

(D) To prevent hunting and provide the starting torque 8. In an induction motor, at no-load the slip is generally (A) 1 (B) More than 1

(C) 0 (D) Less than 0

9. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor current will be (A) 50 Hz (C) 5 Hz (B) 25 Hz (D) 2 Hz 10. Which of the following motor has high starting torque? (C)Both 1 & 2 (A)Slip ring Induction motor (D)None of the above (B) Squirrel cage induction motor