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Electrical Engineering (EE) Exam  >  Electrical Engineering (EE) Test  >  Electrical Machines  >  Test: Doubly Excited Magnetic System - Electrical Engineering (EE) MCQ

Doubly Excited Magnetic System - Free MCQ Practice Test with solutions,


MCQ Practice Test & Solutions: Test: Doubly Excited Magnetic System (10 Questions)

You can prepare effectively for Electrical Engineering (EE) Electrical Machines with this dedicated MCQ Practice Test (available with solutions) on the important topic of "Test: Doubly Excited Magnetic System". These 10 questions have been designed by the experts with the latest curriculum of Electrical Engineering (EE) 2026, to help you master the concept.

Test Highlights:

  • - Format: Multiple Choice Questions (MCQ)
  • - Duration: 30 minutes
  • - Number of Questions: 10

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Test: Doubly Excited Magnetic System - Question 1
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Which of the following are examples of doubly-excited magnetic systems?

Detailed Solution: Question 1

All of the above applications require two independent sources of excitation.

Test: Doubly Excited Magnetic System - Question 2
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In a doubly excited magnetic system with salient pole type stator and rotor, if the rotor is not allowed to move, then the equation for magnetic field stored energy in establishing the currents from zero to is and ir is __________

Detailed Solution: Question 2

As the rotor is not allowed to move, dWmech = 0, thus dWelec = 0 + dWfld = isdΨs + irdΨr, if in this equation, we introduce the self and mutual inductance terms, (Ψs = Lsis) and integrate the resulting equation from 0 to is, 0 to ir and 0 to iris, the respective terms, finally we get Wfld = 1/2 is2Ls+ 1/2 ir2Lr + Mrs is ir.

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Test: Doubly Excited Magnetic System - Question 3
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In a doubly excited magnetic systems, the magnetic torques and forces act in such a direction as to tend to ___________

Detailed Solution: Question 3

Te = ∂Wfld(is,ir,θr)/∂θr = ∂Wfld1(is,ir,θr)/∂θr
fe = ∂Wfld(is,ir,x)/∂x = ∂Wfld1(is,ir,x)/∂x
The positive sign in the formula indicates that force/torque acts in a direction as to tend to increase both field energy and co-energy.

Test: Doubly Excited Magnetic System - Question 4
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Which component of torque in the following equation is called the electromagnetic torque of electromagnetic energy conversion device?

Te = 1/2is2dLs/dθr + 1/2ir2dLr/dθr+isirdMsr/dθr

Detailed Solution: Question 4

The torque developed by the interaction of stator and rotor magnetic fields is the electromagnetic torque or interaction torque.

Test: Doubly Excited Magnetic System - Question 5
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Which of the following statements are true about electromagnetic torques and reluctance torques?
(i) electromagnetic torque can exist only if both windings carry current
(ii) reluctance torque depend on the direction of current in stator or rotor windings
(iii) reluctance torque doesn't depend on the direction of current in stator or rotor windings
(iv) electromagnetic torque depend on the direction of currents is and ir
(v) electromagnetic torque doesn't depend on the direction of currents is and ir

Detailed Solution: Question 5

Reluctance torque:
1/2is2dLs/dθr and 1/2ir2dLr/dθr
Positive or negative value of current doesn’t affect the torque direction. The interaction/electromagnetic torque = isirdMsr/dθr, here the direction of is and ir changes the torque.

Test: Doubly Excited Magnetic System - Question 6
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Most of the electromagnetic energy conversion devices belong to __________

Detailed Solution: Question 6

Widely used motor/generators such as synchronous and induction machines belong to doubly excited systems, and many other practical applications require multiply excited magnetic systems.

Test: Doubly Excited Magnetic System - Question 7
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In a doubly excited magnetic system of salient pole stator and rotor, the magnetic torque (Te) depends on which of the following statements?
(i) the instantaneous values of currents is and ir
(ii) the angular rate of change of inductances
(iii) the differential changes of current dis and dir
(iv) only the instantaneous values of self inductance

Detailed Solution: Question 7

Te = 1/2 is 2dLs/dθr + 1/2ir2dLr/dθr + isirdMsr/dθr.

Test: Doubly Excited Magnetic System - Question 8
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In a doubly excited magnetic system of salient pole type stator and rotor, the reluctance torque is present only when _________

Detailed Solution: Question 8

Equation for magnetic torque is Te = 1/2is2dLs/dθr+1/2ir2dLr/dθr+isirdMsr/dθr, if ir = 0, Te = 1/2is2dLs/dθr and if is = 0, then Te = 1/2ir2dLr/dθr, and these equations for torque are called reluctance torques.

Test: Doubly Excited Magnetic System - Question 9
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Which components of torque in the following equation are called the reluctance torque terms?
Te = 1/2is2dLs/dθr + 1/2ir2dLr/dθr+isirdMsr/dθr

Detailed Solution: Question 9

Because the change of reluctance (Rls or Rlr) are responsible for the production of these torques.

Test: Doubly Excited Magnetic System - Question 10
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Singly and doubly excited magnetic systems applications are respectively ________

Detailed Solution: Question 10

Reluctance motors can work on single excitation, and synchronous motors require double excitation.

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About this Electrical Engineering (EE) Practice Test

This test contains 10 MCQs on Doubly Excited Magnetic System with detailed solutions for each question. It is part of the Electrical Machines course on EduRev, designed to align with the current Electrical Engineering (EE) syllabus. Each solution explains not just the correct answer but also gives you an understanding of the topic — not just to attempt the question but also help you prepare for the exam with practice.

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