1. Prevent water and air from entering the transformer

(1) The transformer should be protected from water ingress and damp during operation. The general cap on the top of the bushing, the top of the oil conservator, the raised seat of the bushing and its connecting pipes must be well sealed. Leak detection experiments should be carried out when necessary. If the insulation is found to be damp, corresponding measures should be taken in time.

(2) The transformer after overhaul should be vacuum treated and oiled in accordance with the established instructions, and the vacuum time and oil inlet speed should meet the requirements.

(3) When replenishing oil from the oil conservator or filtering oil with electricity, the accumulated water in the oil conservator should be drained first, and no oil should enter from the lower part of the transformer to prevent moisture. Air or impurities at the bottom of the oil tank enter the transformer body.

(4) When the gas relay sends out the light gas action signal, the gas relay should be checked immediately, and the gas sample should be taken for inspection in time to identify the gas composition, and the oil sample should be taken for chromatographic analysis to find out the cause and eliminate it in time.

(5) Regularly check whether the silica gel of the respirator is normal to ensure smooth flow.

(6) If the transformer is out of service for more than 6 months, relevant tests should be carried out in accordance with the requirements of the pre-test regulations before it is put into operation again.

2. Prevent foreign matter from entering the transformer

(1) When replacing the cooler of the transformer, the oil pipeline and cooler must be repeatedly flushed with qualified insulating oil until the flushed oil test is qualified and there is no foreign matter. If there are too many foreign objects, further inspection and treatment should be carried out.

(2) Prevent the silica gel in the oil purifier device from entering the transformer. The filter should be checked regularly and the adsorbent should be replaced.

(3) Strengthen the regular inspection of whether the oil flow relay indication is normal. Check whether the oil flow relay baffle is damaged or falling off.

3. Prevent transformer insulation damage

(1) When the insulation parts need to be replaced for maintenance, materials and components that meet the requirements of the manufacturer and passed the inspection shall be used, and they shall be dried.

(2) It is strictly forbidden to step on the leads and insulating supports during the operation and maintenance of the transformer

(3) The insulation of the transformer should be checked regularly.

4. Prevent high temperature of transformer coil, insulation deterioration or burnout

(1) Transformer overload operation should be carried out in accordance with GB/T15164-94 "Guidelines for the Load of Oil-immersed Power Transformers" and DL/T572-95 "Power Transformer Operation Regulations".

(2) The hot spot temperature of the transformer during operation shall not exceed the limits and specific limits of GB/T15164-94 "Guidelines for the Load of Oil-immersed Power Transformers".

(3) The air cooler of the transformer is externally flushed with compressed air or water every 1 to 2 years to ensure the cooling effect.

(4) When the transformer is defective or the insulation is abnormal, it shall not exceed the specified current to operate, and strengthen the operation monitoring.

(5) Regularly check the fan blades of the cooler to be balanced, regular maintenance to ensure normal operation, and replace the fan motor that has large vibration and severe wear.

5. Prevent over-voltage breakdown accidents

(1) When switching the no-load transformer, the neutral point must be reliably grounded

(2) The neutral point of the transformer should be equipped with two grounding down conductors connected to different locations of the main grounding grid, and each grounding down conductor should meet the thermal stability requirements

6. Prevent breakdown accidents under working voltage

(1) Partial discharge test should be carried out on the transformer after overhauling, replacing the insulating parts or part of the coil and drying it.

(2) When the oil chromatogram of the transformer is abnormal in operation and the equipment is suspected of discharging faults, a partial discharge test shall be carried out.

7. Prevent the protection device from malfunctioning/refusing to move

(1) The protection device of the transformer must be complete and reliable, and it is strictly forbidden to put the transformer and the equipment on the high/medium/low-voltage side of the transformer into operation without protection.

(2) The gas relay should be installed and adjusted correctly, and tested regularly to eliminate the misoperation factors caused by the short circuit of the contact. For example, install a rain cover to avoid the misoperation of the contact due to moisture.

(3) The action signal of the pressure release valve should be connected to the signal circuit, and the action contacts of the winding thermometer and the top oil thermometer should be connected to the signal circuit.

(4) The transformer should be equipped with a fault recorder, and the backup protection on each side of the transformer should be powered by different DC power sources to prevent the loss of DC for some reason, causing the backup protection to be completely paralyzed, continuously failing for a long time and expanding the consequences of the accident.