What are the functions of current transformer and voltage transformer?

The function of current transformer (CT) is to convert the current with large primary value into the current with small secondary value through a certain transformation ratio, which can be used for protection, measurement and other purposes. For example, a current transformer with a transformation ratio of 400/5 can convert an actual current of 400A into a current of 5 A. ..

The purpose of voltage conversion of voltage transformer is mainly to supply power to measuring instruments and relay protection devices, measure the voltage, power and electric energy of the line, or protect valuable equipment, motors and transformers in the line when the line fails. Therefore, the capacity of voltage transformer is very small, generally only a few volts, dozens of volts, and the maximum is not more than 1000 volts.

Extended data:

Classification of voltage transformers

1, electromagnetic voltage transformer: It is a device that converts voltage or current according to the principle of electromagnetic induction.

2. Capacitive voltage transformer: Capacitive voltage transformer (CVT) is a voltage transformer which is divided by series capacitors and then isolated by electromagnetic transformer. Such as instrument and relay protection. It can also couple the carrier frequency to the transmission line for long-distance communication, telemetry, selective line high-frequency protection, remote control, telex typing and so on.

3. Electronic voltage transformer: a device consisting of one or more voltage or current sensors connected to the transmission system and the secondary converter, which is used to transmit the measured data and provide them to measuring instruments, meters and relay protection or control devices.

Classification of current transformers:

1. Measuring current transformer (or measuring winding of current transformer): within the normal working current range, provide the measuring and metering device with the current information of the power grid.

2. Protective current transformer (or protective winding of current transformer): In case of power grid fault, provide power grid fault current information to relay protection and other devices.

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