Transformer faults can be divided into internal faults and external faults.
Internal faults refer to faults that occur inside the casing, including phase-to-phase short-circuit faults of windings, inter-turn short-circuit faults of one-phase windings, short-circuit faults between windings and iron cores, and wire break faults of windings.
External faults refer to various phase-to-phase short-circuit faults between external lead-out wires of transformers, and single-phase grounding faults caused by flashover of lead-out insulation bushings through the casing.
Transformer faults are very harmful. Especially when internal faults occur, the high-temperature arc generated by the short-circuit current will not only burn the insulation and iron core of the transformer windings, but also cause the transformer oil to decompose and produce a large amount of gas due to heat, causing the transformer casing to deform or even explode. Therefore, the transformer must be removed when it fails.
The abnormal conditions of the transformer mainly include overload, oil level reduction, overcurrent caused by external short circuit, excessive oil temperature of the operating transformer, excessive winding temperature, excessive transformer pressure, and cooling system failure. When the transformer is in an abnormal operating state, an alarm signal should be given.
