Question

(a) What are different losses in transformer, suggest steps to minimise the losses in transformer.
(b) State principle and explain the working of transformer

Answer 1

Core loss of a transformer consists of two parts
1) Hysteresis losses 2) Eddy Current losses. In order to reduce eddy current losses, the magnetic core of the transformer is not made from a magnetic material; because in this case the circulating eddy current flowing will be higher. Instead the magnetic core is a stack of thin silicone steel lamination and the laminations are insulated from one an other by thin layer of varnish in order to reduce eddy current and hence eddy current losses.
In order to minimize hysteresis loses, Soft magnetic materials eg: Si Steel, steel alloys, Mn-Zn ferrite are used because they have high saturation magnetization, Low coercivity, High magnetic permeability etc. which reduce losses due to hysteresis.

b. The working of the transformer is as follows:

It works on the principle of mutual induction of two coils or Faraday Law’s of Electromagnetic induction. When the current in the primary coil is changed the flux linked to the secondary coil also changes. Hence an EMF is induced in the secondary coil due to Faraday laws of electromagnetic induction.

The transformer is based on two principles: first, that an electric current can produce a magnetic field (electromagnetism), and, second that a changing magnetic field within a coil of wire induces a voltage across the ends of the coil. Changing the current in the primary coil changes the magnetic flux that is developed. The changing magnetic flux induces a voltage in the secondary coil.