Principle of electromagnetic induction and normal current of high accuracy current transformer

- Jun 24, 2019-

The high accuracy current transformer mainly relies on the principle of electromagnetic induction in the process of operation, and is mainly composed of a closed core and a winding during operation. Its primary winding turns are few, and it is in the line of the current that needs to be measured. Therefore, it often has all the current flowing through the line, and the number of turns in the secondary winding is relatively large. It is connected in series between the measuring instrument and the protection circuit. When the device is working, its secondary circuit is always closed, so the impedance of the series coil of the measuring instrument and the protection circuit is small, and the working state of the current transformer is close to the short circuit.

High accuracy current transformer are divided into: 1. Overload protection current transformer, 2. Differential protection current transformer, 3. Ground protection current transformer (zero sequence current transformer)

The high accuracy current transformer mainly cooperates with the relay device to provide a signal to the relay device to cut off the fault circuit when the line is short-circuit overloaded, etc., to protect the safety of the power supply system. Protection of the operating conditions of the current transformer and the current used for measurement.

The transformers are completely different, and the protection transformers only start working effectively when they are several times larger than the normal current. The main requirements of the protection transformer: 1. reliable insulation, 2. large enough accuracy limit coefficient, 3. sufficient thermal stability and dynamic