What is Transformer and Transformer Bushing?

What is a transformer? 

Basically a transformer is a device which is used to step up or step down the voltage as required. Transformers are required in power transmission and generation stages, with high voltages.

Since the transformer works at very high voltage, it is also necessary to take care that it works properly without any leakage or damage. And the transformer has one component that helps it to function properly, that component is the bushing. And without bushings, it is not possible to operate the transformer in any high-voltage condition and that generally in KV.

What is Transformer Bushing? 

A bushing is basically an electrical insulator that allows the safe passage of electrical conductor current. It is similar to any insulator around the conductor, which helps prevent any untoward incident from occurring. A transformer has two windings - primary and secondary (HV and LV). It makes connections with external wires to conduct electricity. Although the transformer also includes LV, it is not so low as to be negligible. When an electric current passes through a conductor, it creates an electromagnetic field around it. So, the higher the current and voltage, the higher the field generated. Coming to a transformer, the current around the windings is so strong, that it can ionize the insulator externally and make it conductive. If the dielectric strength of an insulator is broken, it will start to conduct and once the insulator becomes conductive, it can either pass leakage current or even create a short circuit under ground.

This will be very harmful due to its proximity to the transformer, which may damage the transformer as well. To protect the transformer body from that, bushings are used immediately before and after the windings.