Electrical Machines Mock Test 7

10%

Question 1 of 10

1. An induction motor X operating at the slip of 3%. An induction motor Y operating at slip of 40%.

Both the machine X and Y are stable

Machine Y is only stable

Machine X is only stable

Neither X nor Y is stable

Question 1 of 10

Question 2 of 10

2. Synchronous motor has been preferred for driving the loads requiring high power at low speeds.

True

False

Question 2 of 10

Question 3 of 10

3. A three phase, 50 Hz induction motor has a full load speed of 1440 rpm. Speed of the rotor field w.r.t. stator field is?

150 rad/s

145 rad/s

6.28 rad/s

zero

Question 3 of 10

Question 4 of 10

4. In a 3-phase cylindrical rotor alternator the _________

armature mmf leads air gap flux and air gap flux leads field flux

field mmf leads air gap flux, air gap flux lags armature flux

field mmf leads air gap flux, air gap flux leads armature flux

armature mmf leads air gap flux and air gap flux lags field flux

Question 4 of 10

Question 5 of 10

5. The 3-phase induction motor with rotor circuit open will _________

get over heated

run normally

not run

make noise

Question 5 of 10

Question 6 of 10

6. A three phase, 50 Hz induction motor has a full load speed of 1440 rpm. Speed of the stator field revolving rotor structure is?

145 rad/s

6.28 rad/s

157 rad/s

150 rad/s

Question 6 of 10

Question 7 of 10

7. For a 4 pole three phase induction motor having synchronous speed of 1500 rpm is operating at 1450rpm. The frequency of the induced emf in rotor is?

150 Hz

100 Hz

50 Hz

0 Hz

Question 7 of 10

Question 8 of 10

8. Choose the appropriate synchronous generators used in the thermal power stations.

(i) cylindrical rotor
(ii)slip rings and brushes
(iii)laminated rotor
(iv)stator slots in the multiple of 6
(v)salient rotor

(i), (ii), (iv)

(i), (iii)

(ii), (iii), (iv), (v)

(ii), (iii), (v)

Question 8 of 10

Question 9 of 10

9. On increasing the starting torque of the induction motor, the maximum torque is also increased.

True

False

Question 9 of 10

Question 10 of 10

10. In a three phase induction motor, rotor current in each phase lags behind the generated emf in that phase to rotor by a power factor angle of _________

atan(x1/r1)

atan(r1/x1)

atan(r2/x2)

atan(x2/r2)

Question 10 of 10