A transformer is a device used in the power transmission of electric energy. The transmission current is AC. It is commonly used to increase or decrease the supply voltage without a change in the frequency of AC between circuits.
Even though transformers are very efficient machines, they do result in small energy losses due to four main causes:
The resistance of windings – The low resistance copper cable used for the windings remains resistant and thus leads to heat loss. In order to minimize this loss thick wires with considerably low resistance are used.
Leakage of flux – If the core design is not good then the flux produced by the primary coil may not all be connected to the secondary coil. This can be reduced by considering the core of shell type.
Eddy currents loss – The varying magnetic field not only induces secondary coil currents but also iron core currents themselves. In the iron core, these currents flow in small circles and are termed as eddy currents. The eddy current loss can be minimized by considering the laminated core.
Hysteresis – This is because of the repeated iron core magnetisation and demagnetisation induced by the alternating input current. By using alloys such as mumetal or silicon steel, this can be reduced.