Three Phase Transformer

Today we study about Three phase transformer.

Working principle and construction of three phase transformer.

Principle- The working principle of three phase transformer three single phase transformer have each a  primary winding upon one leg. These transformer are symmetrically wound and each winding is connected to one wire of three phase system.

Figure. 1

Construction

In this the three core are placed 120 degree electrical apart so that the the empty legs of three flux produced by three phase current I1 I2 I3 the sum of three phase current is I1 I2 I3 at any instant is zero the sum three fluxes must be zero. In this no appreciable flux exists in common leg and this leg can be eliminated without any disturbance to the existing condition. Now any two legs act as the return for third just as in the 3-phase system any two wire act as the return for third just as in the 3-phase system any two wires act as the return for the current in third wire.

          A three phase shell type transformer does not differ from three phase single phase transformer put side by side some iron is saved due to the joint use of the magnetic circuit independent of other and in this type of transformer are more independent than they are in core type.

Three Phase Core type and Shell type Transformer