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

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


Test Description

10 Questions MCQ Test Electrical Machines - Test: Doubly Excited Magnetic System

Test: Doubly Excited Magnetic System for Electrical Engineering (EE) 2024 is part of Electrical Machines preparation. The Test: Doubly Excited Magnetic System questions and answers have been prepared according to the Electrical Engineering (EE) exam syllabus.The Test: Doubly Excited Magnetic System MCQs are made for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Doubly Excited Magnetic System below.
Solutions of Test: Doubly Excited Magnetic System questions in English are available as part of our Electrical Machines for Electrical Engineering (EE) & Test: Doubly Excited Magnetic System solutions in Hindi for Electrical Machines course. Download more important topics, notes, lectures and mock test series for Electrical Engineering (EE) Exam by signing up for free. Attempt Test: Doubly Excited Magnetic System | 10 questions in 30 minutes | Mock test for Electrical Engineering (EE) preparation | Free important questions MCQ to study Electrical Machines for Electrical Engineering (EE) Exam | Download free PDF with solutions
Test: Doubly Excited Magnetic System - Question 1

Which of the following are examples of doubly-excited magnetic systems?

Detailed Solution for Test: Doubly Excited Magnetic System - Question 1

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

Test: Doubly Excited Magnetic System - Question 2

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 for Test: Doubly Excited Magnetic System - Question 2

As the rotor is not allowed to move, dWmech = 0, thus dWelec = 0 + dWfld = is+ irr, if in this equation, we introduce the self and mutual inductance terms, (Ψ= 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.

1 Crore+ students have signed up on EduRev. Have you? Download the App
Test: Doubly Excited Magnetic System - Question 3

In a doubly excited magnetic systems, the magnetic torques and forces act in such a direction as to tend to ___________

Detailed Solution for Test: Doubly Excited Magnetic System - Question 3

Te = ∂Wfld(is,irr)/∂θr = ∂Wfld1(is,irr)/∂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

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 for Test: Doubly Excited Magnetic System - 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

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 for Test: Doubly Excited Magnetic System - 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

Most of the electromagnetic energy conversion devices belong to __________

Detailed Solution for Test: Doubly Excited Magnetic System - 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

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 for Test: Doubly Excited Magnetic System - Question 7

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

Test: Doubly Excited Magnetic System - Question 8

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

Detailed Solution for Test: Doubly Excited Magnetic System - Question 8

Equation for magnetic torque is T= 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

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 for Test: Doubly Excited Magnetic System - 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

Singly and doubly excited magnetic systems applications are respectively ________

Detailed Solution for Test: Doubly Excited Magnetic System - Question 10

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

19 videos|90 docs|25 tests
Information about Test: Doubly Excited Magnetic System Page
In this test you can find the Exam questions for Test: Doubly Excited Magnetic System solved & explained in the simplest way possible. Besides giving Questions and answers for Test: Doubly Excited Magnetic System, EduRev gives you an ample number of Online tests for practice

Top Courses for Electrical Engineering (EE)

19 videos|90 docs|25 tests
Download as PDF

Top Courses for Electrical Engineering (EE)