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Use and protection of voltage transformers
- Jun 01, 2018 -

The correct phase of the voltage transformer is very important in the application, which requires the corresponding connection polarity. Once the wrong terminal is used, the polarity will be used

Will make the voltage and phase change 180 °, thus is one mark polarity, secondary side.

In operation, the voltage transformer must ensure that the secondary side cannot be short-circuited, because it is a voltage source with minimal internal resistance when it is in operation

The load impedance is large, which is equivalent to the open road state, and there is only a small load current on the secondary side. If the second side short circuit, the load impedance is zero, will be generated

Large short circuit current, huge heat will burn the transformer, even leading to equipment explosion accidents.

In order to achieve good protection of the voltage transformer during operation, the following measures can be taken:

(1) the secondary side fuse is a reliable measure to ensure the safe operation of the voltage transformer. It is necessary to select the appropriate fuse and install the locking device.

(2) to avoid voltage imbalance at both ends of the open triangle winding, high voltage exists for a long time. Install and combine the two ends of the open triangle winding

When the open triangle induces the zero sequence voltage, the zero sequence current can be circulated and the high voltage coil can be demagnetized

It also inhibits resonance.

(3) in the circuit of the insulation monitoring device, in order to enable the insulation monitoring relay and voltmeter to accurately reflect the grounding fault of the power grid, attention must also be paid to and

Voltage transformers and structural problems. That is, in order to reflect each relative ground voltage, each phase winding of the high voltage side of the voltage transformer must be connected to the phase

Between ground and ground, the high-voltage winding must be star-shaped, and there must be neutral ground. Meanwhile, the low-voltage side two winding of the voltage transformer must also be grounded

It's a little grounded.