(1) The transformer must be well sealed during transportation and storage, and measures must be taken to prevent water ingress during installation and operation; During installation, special attention must be paid to the sealing of components higher than the oil level of oil storage tank, such as the top of casing, explosion-proof membrane, the top of oil storage tank and respiratory tract. , and should carry out leak detection test. Combined with annual maintenance, the sealing condition of these parts should be checked.

(2) When installing the transformer with strong oil circulation, ensure that the connection between the body and each part of the cooling system is well sealed. Gaskets should be installed correctly and kept intact, and those with manufacturing defects should be handled well, such as rubber gasket of submersible pump, sealing packing of oil inlet valve stem, connecting pipe of differential pressure relay, etc. When replacing the rubber gasket, the rubber gasket material with unknown performance should be sampled for oil resistance test.

(3) Before installation, the water-cooled oil cooler and submersible pump shall be tested for leakage according to the manufacturer's installation instructions. For several oil coolers running in parallel, it is best to install a check valve at the outlet of each submersible pump to prevent the oil flow in the standby oil cooler from flowing backwards. The operating and standby oil coolers must ensure that the oil pressure is greater than the water pressure. The oil inlet valve of submersible pump should be fully opened, and the oil flow rate should be adjusted with the oil outlet valve to avoid negative pressure. During operation, the indication of differential pressure relay and pressure gauge and whether there is oil flower in outlet water should be monitored regularly (each oil cooler should be equipped with a drain valve to monitor whether there is oil flower in outlet water). Measures should be taken in the north to prevent the copper tube from freezing and cracking when the oil cooler stops.

(4) Explosion-proof gas cylinders should be connected to the oil storage tank or connected to the atmosphere through breathing apparatus. Regularly drain the accumulated water in the lower part of the oil storage tank.

(5) Pay attention to the refueling and maintenance of ventilator oil seal to ensure smooth flow. The dryer should be kept dry.

(Transformers of 220kV and above should be filled with vacuum oil to eliminate air bubbles in the coil. 1 10 kV transformer should actively create conditions for vacuum oil injection.

(7) Before the transformer is put into operation, special attention should be paid to the elimination of internal air, such as the flange of high-pressure casing, the lifting seat, the dead zone in the oil pipeline and the top of the oil cooler. Before the installation of strong oil circulating transformer is completed and put into operation, all cooling equipment should be started to circulate oil for a long time, so that residual air can escape.

(8) When filling or filtering oil into the oil storage tank, the accumulated water in the oil storage tank should be drained first. Oil should not be injected from the lower part of the transformer to prevent air or moisture and sundries at the bottom of the box from being brought into the coil.

(9) In case of light gas signal, gas (even air) should be taken in time to determine the composition, and oil samples should be taken for chromatographic inspection, so as to find out the reason and troubleshoot in time.

2. Prevent welding slag and copper wire from entering the transformer.

(1) When installing the transformer, it should be inspected by hanging the cover, remove all residual sundries inside, and clean the iron core and coil with oil as much as possible. If possible and necessary, the core should be hoisted to completely remove the sundries at the bottom of the box. Attention should be paid to removing impurities from the transformer oil inlet header with guided cooling.

(2) Before installation, the tubing, oil cooler and submersible pump should be cleaned and washed with oil.

(3) The oil filter should be installed correctly. Measures should be taken to prevent activated alumina or silica gel in the oil purifier from rushing into the transformer. For transformers that have been washed with alumina or silica gel, maintenance should be arranged as soon as possible.

(4) In order to prevent the copper wire mesh from rushing into the transformer, the copper wire mesh should be replaced with a sintered filter [refer to the requirements of Shenyang Transformer Factory (76) No.97 document]. For transformers that have been found to have copper wire mesh rushing in, maintenance should be arranged as soon as possible.

3. Prevent insulation damage

(1) When hanging the bell jar, the insulation of the transformer should be prevented from being damaged, and special attention should be paid to the transformer with tight internal insulation distance to avoid the bell jar from damaging the lead and bracket. For this reason, we can consider the hidden nail that does not make it deviate when hanging the bell cover. When installing the high-voltage bushing, care should be taken not to twist the lead or use excessive force to avoid damaging the lead root and coil insulation. If the lead is too long or too short, it should be treated. The rubber tube shell at the lower part of the shell shall be installed according to the manufacturer's drawings and instructions. It is necessary to prevent the lead from colliding and the shell from making the insulation distance insufficient. During maintenance and inspection, it is forbidden to step on the root of the conductor.

(2) When inspecting the transformer suspension cover, tighten the bolt and pressure nail of the clamp to prevent the coil from shifting due to current impact during operation.

(3) For transformers with short circuit at the outlet and abnormal operation, especially aluminum wire transformers, necessary tests or inspections should be conducted according to specific conditions to prevent the defects from expanding.

(4) When insulation parts need to be replaced during installation and maintenance, materials or parts that have passed the test must be adopted.

4. Prevent the coil from overheating, insulation deterioration or burning.

(1) transformer protection device must be perfect and reliable. Gas relay should be installed and adjusted correctly, and checked regularly to eliminate misoperation factors. Heavy gas protection should trip. The tripping DC power supply must be reliable. Unprotected transformers are not allowed to be put into operation. If the protection needs to be stopped for a short time due to work, measures should be taken and it should be resumed immediately afterwards.

Because of the large resistance of sintering filter screen, it is easy to form negative pressure, and later the manufacturer replaced it with paper filter screen.

(2) During earthquake prediction, according to the specific situation of transformer and the type of gas relay, determine the trip or signal of heavy gas input. Transformer with heavy gas trip caused by earthquake should be inspected before power supply is restored, and can be put into operation only after it is confirmed to be abnormal.

(3) Reasonable control of the top oil temperature rise during operation, especially for transformers with strong oil circulation. According to the operation and measurement results, the top oil temperature rise of different transformers is quite different under rated load, so it cannot be considered that the top oil temperature rise of some transformers is low and the output is redundant. All kinds of thermometers should be checked regularly, and the overtemperature signal should be accurate and reliable.

(4) For transformers that have doubts about the load capacity or have been improved to increase the output, the load capacity should be determined by measuring the average coil temperature. Under normal circumstances, the corresponding oil level temperature rise when the average coil temperature rises to 65℃ is taken as the limit of operation monitoring. When the current density of the coil exceeds the design standard of similar transformers, the temperature of the hottest spot of the coil should not exceed 105℃. The difference between the temperature rise at the hottest point of the coil and the average temperature rise should be considered, which will increase, especially for the turn-key insulated coil, the average temperature rise should be reduced appropriately to determine the rated output of the transformer.

(5) Forced oil circulation air cooling, forced oil circulation water cooling transformer, when an accident occurs, remove the cooling system (for strong oil circulation air cooling, it means stopping the fan and oil pump; Strong oil circulation water cooling, that is, stop water and oil circulation), the allowable running time under rated load: 20 minutes when the capacity is 125 MVA and below, and 10 minute when it is above. According to the above regulations, when the oil surface temperature does not reach 75℃, it is allowed to rise to 75℃, but not more than 65438 0 hours.

(6) Strong oil circulating cooling system must have two reliable power supplies, and should be equipped with automatic switching devices, and switch tests should be carried out regularly. Signal devices shall be complete and reliable.

(7) In order to prevent the fan motor of air-cooled radiator from being damaged a lot, the blades should be balanced and the angle should be adjusted, and the cast aluminum end cover of the motor with serious wear can be changed to cast iron end cover. Maintenance work should be carried out to ensure normal operation.

(8) Transformers of 31500 KVA and above should create conditions to install the upper oil temperature telemetry device.

(9) The alcohol thermometer shall be installed on the transformer wall near the top, so as to check the indication of the sector thermometer when necessary.

(10) Turn-key insulation reinforcement section, check whether the oil circuit is blocked during maintenance, and handle it if necessary.