Transformer Protection Methods

Generally used protection methods for transformers. The abnormal working conditions of transformers mainly include overload, overcurrent caused by external short circuit, neutral point overvoltage caused by external ground short circuit, oil level reduction caused by oil leakage in the oil tank, or temperature caused by cooling system failure. Elevate etc.

In addition, due to the high rated operating magnetic flux density of large-capacity transformers, their operating magnetic flux density is proportional to the voltage-frequency ratio. When over-voltage or low-frequency operation occurs, the transformer may cause over-excitation failure.

1. Gas protection: Protect the transformer from internal short circuit and low oil level fault.

2. Differential protection, current quick-break protection: protects phase-to-phase short circuit of transformer windings or lead wires, short circuit to ground in large ground current systems, and short circuit between winding turns.

3. Overcurrent protection: protects external phase-to-phase short circuit and serves as backup protection for gas protection and differential protection (or current quick-break protection).

4. Zero-sequence current protection: protects external single-phase grounding short circuit of large grounding current system.

5. Overload protection: protects symmetrical overload and only acts on signals.

6. Over-excitation protection: Protect the transformer from over-excitation exceeding the allowable limit.