Instrument transformers , like conventional transformers, work on the principle of mutual induction. Instrument transformers, unlike conventional transformers: are used for measuring high voltage and current parameters in electrical circuits, are also used for obtaining electrical feed backs to protection devices in the electrical circuits.
There are two types of instrument Transformers.
1.Current transformers ( IS 2705 , IEC 60044-1)
2.voltage transformers (IS 3156, IEC 60044-2)