GATE EE 2021 Set 1 — Question 18

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MCQ+1 / -0.33EasyArmature Reaction & CommutationDC MachinesElectrical MachinesCrawling & CoggingThree-Phase Induction MachinesStarting of Synchronous MotorsSynchronous Machines

Electrical Machines → DC Machines → Armature Reaction & Commutation

Last updated 5 September 2026

Question

Consider the table given: Constructional feature Machine type Mitigation (P) Damper bars (S) Induction motor (X) Hunting (Q) Skewed rotor slots (T) Transformer (Y) Magnetic locking (R) Compensating winding (U) Synchronous machine (Z) Armature reaction (V) DC machine The correct combination that relates the constructional feature, machine type and mitigation is

Constructional feature	Machine type	Mitigation
(P) Damper bars	(S) Induction motor	(X) Hunting
(Q) Skewed rotor slots	(T) Transformer	(Y) Magnetic locking
(R) Compensating winding	(U) Synchronous machine	(Z) Armature reaction
	(V) DC machine

Correct answer (B) P-U-X, Q-S-Y, R-V-Z Solution Damper bars (P) are used in Synchronous machines (U) to provide damping torque and mitigate Hunting (X) . Skewed rotor slots (Q) are used in Induction motors (S) to reduce the effect of space harmonics, which helps in mitigating Magnetic locking (Y) (cogging). Compensating windings (R) are used in DC machines (V) to neutralize the cross-magnetizing effect of Armature reaction (Z) in the interpolar region. Thus, the correct combination is P-U-X, Q-S-Y, R-V-Z. Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (B) P-U-X, Q-S-Y, R-V-Z Solution Damper bars (P) are used in Synchronous machines (U) to provide damping torque and mitigate Hunting (X) . Skewed rotor slots (Q) are used in Induction motors (S) to reduce the effect of space harmonics, which helps in mitigating Magnetic locking (Y) (cogging). Compensating windings (R) are used in DC machines (V) to neutralize the cross-magnetizing effect of Armature reaction (Z) in the interpolar region. Thus, the correct combination is P-U-X, Q-S-Y, R-V-Z.

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GATE EE 2021 Set 1 — Question 18

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