Question

When is the double layer bar or wave windings made use of?

(a) when single turns coils are necessary as with turbo alternators and unipolar low voltage machines

(b) when single turns coils are necessary as with turbo alternators and bipolar low voltage machines

(c) when single turns coils are necessary as with turbo alternators and multipolar low voltage machines

(d) when double turns coils are necessary as with turbo alternators and unipolar low voltage machines

The question was posed to me in an online interview.

Origin of the question is Armature Design in chapter Design of Synchronous Machines of Design of Electrical Machines

Answer 1

Right answer is (c) when single turns coils are necessary as with turbo alternators and multipolar low voltage machines

The explanation is: The double layer bar or wave windings are used when the single turns coils are necessary. They are also made use of with the multipolar low voltage machines.