In lap winding it is seen that
the coils are connected in series .So that the induced voltages are additive,
that is one coil side under north pole is connected by end connections to the
coil side under the south pole. This is in turn is connected in series with
another coil having a coil side under the same north pole as the previous coil.
But in a wave winding coil A has one coil side under the north pole and the
other side under the south pole, coil B is connected in series with coil A.
Coil B is not located under the same poles as coil A but under the next pair of
poles as demonstrated in figure 1. As a sequence coil B and C is under the set
of poles.
How can the problem be remedied : No residual magnetism, reversed field connection and high resistance of field circuit are responsible for the failure of build up process of a dc generator. The factors are explained below: No residual magnetism: For the starting build up process requires some residual magnetism in the magnetic circuit then no voltage will be generated that can produce current flow through field circuit. Reversed field connection: The voltage induced inside the coil of field circuit due to residual magnetism that can permit the flow of current. For the following direction of this flux will be created and the direction of this flux will be same direction as the residual flux. If the field connections are reversed the lines of flux produced by current flow will oppose the residual flux, as a result generate voltage will decrease rather than increase. So voltage build up process failed. Field circuit resistance too high: A field
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