Question

Dummy coils are used in wave wound d.c. machines to reduce

• A. Hysteresis losses
• B. Mechanical imbalance on armature
• C. Frictional losses
• D. Mechanical imbalance on iron frame

Hint:

Dummy coils help in maintaining physical and mechanical symmetry in DC machines.

Answer 1

The Correct Option is B

Dummy coils are non-connected coils added to maintain mechanical balance on the rotor when winding symmetry isn't achievable.