Definition - What does Instrument Transformer mean?
Instrument Transformer is an electrical device of high accuracy that is used to transform or isolate current or voltage levels. The transformers are specifically designed to be used with the electrical equipment which falls into a variety of devices known as instruments. These instruments include ammeters, watt-hour meters, protection relays, voltmeters, etc. They are most commonly used for metering or operating instrument of high current or high voltage circuits by isolating the secondary control circuitry safely in high currents or voltage.
Petropedia explains Instrument Transformer
Instrument Transformers provide current or voltage signals which are the accurate representations of the values of transmission line in both the phase and magnitude. When the transformers are used for the purpose of protection, their results must represent the values of transmission line accurately during transient and steady state conditions. When used for network control, they supply essential information to determine a state of operating conditions of a network. They are not considered as the perfect devices as they can case losses from the stray inductance and resistance of copper core and winding. They can also be used as insolation transformers in order to produce the secondary qualities used in the phase shifting without arousing any effect on the other devices connected primarily.