Frequently Asked Questions about Transformer Troubleshooting

1 Abnormal noise

(1) If the sound is loud and noisy, it may be a problem with the transformer core. For example, when the clamp or the screw holding down the iron core is loose, the indication of the instrument is generally normal, and the color, temperature and oil level of the insulating oil do not change significantly. At this time, the operation of the transformer should be stopped and checked.

(2) If there is boiling sound of water in the speaker and a "gurgling" sound of bubbles escaping, it may be that there is a serious fault in the winding, which causes the nearby parts to become severely heated and cause the oil to vaporize. This sound will be emitted due to poor contact of the tap changer, severe overheating at local points or short circuit between turns of the transformer. At this time, the transformer should be stopped immediately and inspected.

2 Temperature abnormality

When the load, heat dissipation conditions, and ambient temperature of the transformer remain unchanged, the temperature of the transformer is higher than the original temperature under the same conditions, and has a rising trend. This is also an abnormal rise in the temperature of the transformer. It is also a fault of the transformer as well as an increase in exceeding the limit temperature. symbol.

Reasons for abnormal temperature rise include:

① Short circuit between turns, layers and strands of transformer;

② The transformer core is partially short-circuited;

③The fuel tank, tank cover, etc. are heated due to magnetic leakage or eddy current;

④ Long-term overload operation and accidental overload;

⑤Deterioration of heat dissipation conditions, etc.

If an abnormal temperature of the transformer is found during operation, the cause should be identified first, and then corresponding measures should be taken to eliminate it and lower the temperature. If it is caused by an internal fault of the transformer, the operation should be stopped and inspected.

3 fuel injection explosion

The cause of the oil injection explosion is that the fault short-circuit current and high-temperature arc inside the transformer cause the transformer oil to age rapidly, and the relay protection device fails to cut off the power supply in time, causing the fault to persist for a long time, causing the internal pressure of the box to continue to increase, and the high voltage Oil and gas erupt from the explosion-proof pipe or other weak points in the box, causing an accident.

4 Serious oil leakage

Oil leakage is common in transformers during operation. If the oil level is within the specified range, it can still continue to operate or arrange planned maintenance. However, the transformer oil leaks seriously, or continuously overflows from the damaged area, so that the oil level can no longer be seen on the oil level gauge. At this time, the transformer should be stopped immediately, the leakage should be repaired and the oil should be refueled.