A current transformer (CT) is used for measurement of alternating electric current. Current transformers, together with voltage (or potential) transformers (VT or PT), are known as instrument transformers. When current in a circuit is too high to apply directly to measuring instruments, a current transformer produces a reduced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments.
A current transformer isolates the measuring instruments from what may be very high voltage in the monitored circuit. Current transformers are commonly used in metering and protective relays in the electrical power industry.
|Frequency of operation||50/60Khz||50/60Khz||50/60Khz||50/60Khz|
|Amplitude error||As per std IS 13779 : 1999 (2002) CL 1 & CL 2 for 0.1% And IS 14697 : 1999 (200) for 0.2% - 0.5%|
|Immunity||DC immune||DC immune||Non DC immune||Non DC immune|
- Measuring purposes (the CT lowers the current to be suitable for metering instrument) or,
- Protection of the power circuit (input current for protection relays).