Voltage transformer use - Solutions - Huaqiang Electronic Network

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Due to the use of voltage transformers, various measuring instruments and protection devices are not directly connected to high voltages to ensure the safety of meter measurement and relay protection work, and also solve the difficulties of insulation and manufacturing processes of high voltage measurement. In addition, since the secondary side of the voltage transformer is 10 volts, the measuring instrument and the relay voltage coil are manufactured in a standardized manner.

The structure and working principle of the voltage transformer are the same as those of the ordinary transformer. It is also composed of an iron core, a primary winding, a secondary winding, a terminal and an insulating support. The primary winding of the voltage transformer is connected to the line voltage or phase voltage of the system. The insulation should be determined by the actual system voltage. The primary winding has a large number of turns, and the number of secondary winding turns is rarely supplied to the voltage coil of the meter or relay.

The secondary winding of the voltage transformer is not allowed to be short-circuited. The secondary winding has a voltage of 10 volts and should be connected to a circuit that can withstand 10 volts. The current it passes is determined by the magnitude of the impedance of the secondary circuit. If the secondary short circuit occurs, the impedance is small, and the current flowing through the secondary circuit increases, causing the secondary fuse to melt and affect the meter indication and causing protection misoperation, damaging the voltage transformer.

The secondary circuit of the voltage transformer must be grounded to prevent the primary and secondary insulation from damaging the high voltage string to the secondary side, posing a hazard to personnel and equipment.