Maintenance Of Oil-immersed Transformers

Keeping oil immersed transformers in good working condition requires regular maintenance. In the absence of regular maintenance, your transformer is more likely to experience issues that could lead to bigger operational difficulties. Servicing your machine does not require reactive or condition-based maintenance. Prioritize all device issues for faster resolution.

Oil-immersed transformers should be inspected and maintained on a daily basis as follows:

1. Pull down the isolating switch, disconnect the low-voltage side circuit breaker, and hang the corresponding sign on the handle.
2. Disconnect the load switch on the high-voltage side of the transformer, ensure the grounding knife is closed after disconnection, and complete the safety of the switch.
3. Check the oil transformer room first with a high-voltage electroscope, then using a high-voltage isolation knife, check whether the shell, porcelain bottle, and lead wire are deformed. If the rubber pad is damaged or leaks oil, it needs to be replaced. If there is oil leakage, the rubber pad needs to be replaced. If there is discoloration or serious failure, it should be replaced immediately.
4. The lead terminals, pins, and grounding screws should be tightened again; if there is any looseness, remove the screws and file the surface with a fine flat file. Wipe it with a clean cloth after touching it without any uneven feel. Apply petroleum jelly, replace spring washers, and tighten screws.
5. Clean the transformer body and porcelain bottle with a clean cloth, and check the lighting, heat dissipation, and dust removal equipment around the transformer.
6. On the high voltage side of the transformer, ensure that the load switch is flexible, the contact is good, and the transmission part is lubricated.
7. You should use a 2500V shaker to measure the insulation resistance of the transformer’s high and low voltage coils (to ground and phase to phase) and confirm that it meets the requirements (at room temperature, the high voltage side of a 10KV transformer should have a value greater than 20M2 and the low voltage side should have a value greater than 13MQ.
8. If you find leftover tools in the transformer room, close the isolation switch on the high-voltage side and evacuate the area.
9. Remove the high-voltage grounding knife, check that the grounding is disconnected, close the high-voltage load switch, let the transformer run for a few seconds, and remove the high-voltage side identification plate. More than two people are required.

The transformer should also be stopped immediately when one of the following situations occurs:

1. If possible, the standby transformer should be turned on first
2. During transformer operation, prevents reverse power transfer and discharge to the bus
3. There is an obvious increase in the sound of the compressor, which is very abnormal, and the compressor is popping
4. Oil leakage or injection that lowers the oil level below the gauge’s indicated limit
5. There is severe damage and discharge to the insulating sleeve
6. There is smoke coming from the transformer and it is on fire
7. The transformer’s relevant protection device refuses to respond to a fault that threatens its safety