Electrical Machines Questions and Answers – Production of Torque in Non-Salient Pole Machines

This set of Electrical Machines Multiple Choice Questions & Answers (MCQs) focuses on “Production of Torque in Non-Salient Pole Machines”.

1. The electromagnetic torque in non salient pole machines depends on _________
a) number of poles
b) machine dimensions at the air gap
c) peak value of stator and rotor MMF
d) any of the mentioned
View Answer

2. The torque equation for non salient pole machine is T_e = -(P/2)(μ_oΠrl/g)(F_sF_r)sinλNm. What does the negative sign in the torque expression indicates?
a) stator and rotor MMF tend to reduce angle λ
b) stator and rotor MMF tend to increase angle λ
c) stator tend to reduce the air gap g
d) rotor tend to reduce the air gap g
View Answer

3. Which of the following statements are correct regarding the torque equation in non salient pole machines, T_e = -(P/2)(μ_oΠrl/g)(F_sF_r)sinλNm?
a) stator experiences less torque than rotor and in opposite directions
b) rotor experiences less torque than stator and in same directions
c) stator and rotor experiences equal and opposite torques
d) stator and rotor experiences equal torque and in same directions
View Answer

4. In practice, electromagnetic torque acting on the stator _________
a) rotate in opposite direction to rotor
b) is transmitted to ground
c) makes it rotate in same direction as of rotor
d) none of the mentioned
View Answer

5. Torque angle λ is the angle between ____________
a) stator MMF F_s and resultant MMF F_R
b) stator MMF F_s and rotor MMF F_r
c) rotor MMF F_r and resultant MMF F_R
d) any of the mentioned
View Answer

6. Load angle δ is the angle between ____________
a) stator MMF F_s and resultant MMF F_R
b) stator MMF F_s and rotor MMF F_r
c) rotor MMF F_r and resultant MMF F_R
d) stator MMF F_s and resultant MMF F_R (or) rotor MMF F_r and resultant MMF F_R
View Answer

7. In the design of electromagnetic devices, the maximum value of MMF is limited from the considerations of ____________
a) temperature rise
b) limitation on flux density in teeth
c) torque production rise
d) power rating
View Answer

8. Consider the principle that the torque in a rotating machine is proportional to peak of stator MMF(F_s), rotor MMF(F_r) and the angle between them(δ). Following statements relate to F_s,F_r and δ in different machine. Which of these statements are correct?

(i) δ is fixed in DC machine
(ii) Fs is fixed in DC shunt machine
(iii) δ is variable in induction machine
(iv) Fr is fixed in synchronous machne
(v) Fr is variable in DC machine
(vi) Fr is fixed in induction motor
(vii) resultant of Fs and Fr is fixed in synchronous motor

a) (i), (ii), (iii), (iv) and (vi)
b) (i), (ii), (iii), (v) and (vii)
c) (ii), (iii), (v), (vi) and (vii)
d) (i), (ii), (iv), (v) and (vii)
View Answer

9. In all rotating electrical machine, electrical torque is developed when relative speed between stator field and rotor field is ____________
a) zero
b) equal to rotor speed
c) equal and opposite to rotor speed
d) dependent upon the type of electrical machine
View Answer

Sanfoundry Global Education & Learning Series – Electrical Machines.

To practice all areas of Electrical Machines, here is complete set of 1000+ Multiple Choice Questions and Answers.