Electrical Machines Mock Test 1

10%

Question 1 of 10

1. Electromagnetic torque in rotating electrical machinery is present when ________

both stator and rotor windings carry current

rotor winding alone carries current

air gap is uniform

stator winding alone carries current

Question 1 of 10

Question 2 of 10

2. Electromagnetic force and/or torque developed in any physical system, acts in such a direction as to tend to ____________

decrease the field energy and increase the co-energy at constant current

increase both the field energy and co-energy at constant current

decrease both the field energy and co-energy at constant current

increase the field energy and decrease the co-energy at constant current

Question 2 of 10

Question 3 of 10

3. A 3 phase star connected winding is fed from symmetrical 3 phase supply with their neutrals connected together. If one of the 3 supply lines gets disconnected, then the revolving MMF wave will have a ___________

Constant amplitude but super synchronous speed

Varying speed and a speed fluctuating around the synchronous speed

Varying amplitude but synchronous speed

Constant amplitude but sub synchronous speed

Question 3 of 10

Question 4 of 10

4. The single phase reluctance machine acts as a generator when angle δ is _______

zero

any of the mentioned

negative

positive

Question 4 of 10

Question 5 of 10

5. Armature winding is one in which working ___________

emf is produced by the working flux

emf is produced by the leakage flux

flux is produced by the working emf

flux is produced by field current

Question 5 of 10

Question 6 of 10

6. In a doubly excited magnetic system of salient pole type stator and rotor, the reluctance torque is present only when _____________

both stator and rotor currents are acting

stator current is acting alone

rotor current is acting alone

any of the stator or rotor currents acting alone

Question 6 of 10

Question 7 of 10

7. The basic torque and EMF expression of rotating electrical machines are ____________

none of the mentioned

applicable to AC machines only

applicable to DC machines only

applicable to both AC and DC machines

Question 7 of 10

Question 8 of 10

8. Armature winding carries which of the following current?

load current only

none of the mentioned

magnetizing current only

both magnetizing current and load current

Question 8 of 10

Question 9 of 10

9. In an electro-mechanical energy conversion device, which of the following statements are correct regarding the coupling field?

(i) electrical side is associated with emf and current
(ii) electrical side is associated with torque and speed
(iii) mechanical side is associated with emf and current
(iv) mechanical side is associated with torque and speed

(i) & (ii)

(i) and (iv)

(iii) & (iv)

(ii) & (iii)

Question 9 of 10

Question 10 of 10

10. The electromagnetic torque developed in any physical system, and with magnetic saturation neglected, acts in such a direction as to tend to ____________

decrease the reluctance and increase the inductance

decrease both the reluctance and inductance

increase the reluctance and decrease the inductance

increase both the reluctance and inductance

Question 10 of 10