Causes and Treatment of Transformer Backup Protection Action

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The reason for the backup protection action of the transformer is:

(1) Short circuit on the high-voltage side of the transformer.

(2) Transformer low voltage bus short circuit.

(3) Due to a fault occurring within the range of differential protection, the differential protection failed.

(4) Backup protection malfunction.

(5) There is a fault in the low-voltage line, and the outgoing line protection refuses to operate, causing the transformer to overload and trip.

The handling principle is:

(1) If the overcurrent protection is activated and phenomena such as voltage drop, impact, arc light, sound, etc. are found, the external part of the transformer should be inspected; If the fault can be eliminated in a timely manner, it can be tested once, otherwise safety measures should be taken to prepare for repair; If no issues are found, a test drive can also be performed; For transformers without differential protection, in addition to external inspection, insulation measurement inspection should also be carried out.

(2) If the low-voltage outgoing line malfunctions and the line protection refuses to operate, the faulty line switch can be manually turned off and the transformer can be powered on.

(3) If a fault occurs within the differential protection range and the differential protection fails, it should be handled according to the differential protection action.

(4) If it is a secondary circuit fault, it is a misoperation or accidental touch, and the duty personnel can immediately test the power supply.