ECET EEE 2009-6

1. A d.c sensitive galvanometer connected in the rotor circuit of a 3 phase slip ring induction motor, makes 120 oscillations per minute,then the frequency of the rotor current is

A. 2 Hz
B. 1 Hz
C. 3 Hz
D. 4 Hz

Answer : 2 Hz
Explanation:-

2. If 'Pg' is the rotor Input and 'ωs' is the synchronous speed in rad/sec, then gross torque in N-m is

A. Pg/ωs
B. Pg/ω
C. Pg*ωs
D. Pg*ω

Answer : Pg/ωs
Explanation:-

3. If r2 and x2 are the resistance and reactance per phase of thr rotor at standstill, then the value of the slip at maximum torque is

A. X2/r2
B. r2/x2
C. r2/2x2
D. x2/2r2

Answer : r2/x2
Explanation:-

4. If r2 and x2 are the resistance and reactance per phase of thr rotor at standstill,the condition for starting torque is equal to full load torque is

A. r2=x2
B. r2=2x2
C. r2=(x2/2)
D. r2=3*x2

Answer : r2=x2
Explanation:-

5. In a double cage induction motor, the outer cage has

A. High inductance
B. High resistance
C. Low resistance
D. High leakage reactance

Answer : High resistance
Explanation:-

6. Salient pole alternators are used when

A. The speed of the alternator is low
B. The power required is large
C. The speed of the alternator is high
D. Voltage to be generated is high

Answer : The speed of the alternator is low
Explanation:-

7. Which of the following methods is best for predetermining the voltage regulation of an alternator.

A. E.M.F
B. M.M.F
C. Potier method
D. Direct Test

Answer : Potier method
Explanation:-

8. In an alternator, the terminal voltage is mainly effected by

A. Armature resistance
B. Armature leakage reactance
C. Armature reaction
D. Armature reaction and power factor

Answer : Armature reaction
Explanation:-

9. The locus of stator current of a synchronous motor when the developed power is constant, is

A. An ellipse
B. Straight line
C. Circle
D. Parabola

Answer : Straight line
Explanation:-

10. Which is the conventional source of energy

A. Solar
B. Radioactive substances
C. Geothermal
D. Wind

Answer : Radioactive substances
Explanation:-