Electrical Machines Questions and Answers – Torque Production and Dynamic Equations

This set of Electrical Machines Multiple Choice Questions & Answers (MCQs) focuses on “Torque Production and Dynamic Equations”.

1. The magnitude of electromagnetic or interaction torque, in all rotating machines, is given by ____________
a) T_e ∝ (stator field strength)sinδ
b) T_e ∝ (rotor field strength)sinδ
c) T_e ∝ (stator field strength)(rotor field strength)sinδ
d) T_e ∝ sinδ
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2. In a rotating electrical machine with 2 poles on the stator and 4 poles on the rotor, spaced equally, the net electromagnetic torque developed is ____________
a) maximum
b) zero or no torque is developed
c) minimum
d) none of the mentioned
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3. For the development of electromagnetic torque in a rotating electrical machine, the number of rotor poles must be ____________
a) greater than the stator poles
b) less than the stator poles
c) equal to the stator poles
d) either greater or lesser than the stator poles
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4. Torque angle ‘δ’ is the angle between ____________
a) rotor field axis and resultant field axis
b) stator field axis and rotor field axis
c) stator field axis and mutual field axis
d) stator field axis and resultant field axis
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5. The interaction torque in a rotating electrical machine depends on which of the following components?

(i) sinδ
(ii) cosδ
(iii) torque angle δ
(iv) stator field strength
(v) rotor field strength

a) (i), (iv), (v)
b) (ii), (iii), (v)
c) (i), (iii), (v)
d) (ii), (iv), (v)
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6. The basic torque and EMF expression of rotating electrical machines are ____________
a) applicable to DC machines only
b) applicable to AC machines only
c) applicable to both AC and DC machines
d) none of the mentioned
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7. The final forms of the expression for generated EMF and torque,for AC and DC machines differ, because ____________
a) the fundamental principles underlying their operation are same
b) the fundamental principles underlying their operation are different
c) their construction details are same
d) their construction details are different
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8. The voltage equation for the electrical system, in an electromechanical energy conversion device is as follows:
v_t=ir+Ldi/dt+i(dL/dθ_r)ω_r = (i)+(ii)+(iii)
What does the (ii) and (iii) terms represent respectively?
a) transformer voltage term and speed/rotational voltage term
b) speed/rotational voltage term and transformer voltage term
c) force voltage term and transformer voltage term
d) none of the mentioned
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9. For an inductor made from magnetic core, with two air gaps of equal length g, exciting coil with 1000 turns, A=5cm∗5cm and g=1cm, what will be the coil inductance?
a) 0.314H
b) 0.157H
c) 0.078H
d) 0.628H
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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.