How Engineering Works Staff answered 7 years ago
An ‘instrument transformer’ is a category of transformer used to supply measuring instruments or protective relays. There are two types of instrument transformer: a ‘voltage transformer’ (known as’potential transformer’ in North America), and a ‘current transformer’. They are used with high-voltage systems, where it is hazardous to connect instruments directly to such systems.
Voltage tranformers are used to reduce high-voltages down to a level that can be safely applied to voltmeters, or to the voltage-coils of wattmeters or energy meters, or to protective relays, while electrically-isolating those instruments (and personnel) from the high-voltage supply.
Current tranformers are used to reduce high-voltage currents down to a level that can be safely applied to ammeters, or to the current-coils of wattmeters or energy meters, or to protective relays, while electrically-isolating those instrument (and personnel) from the high-voltage supply.
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