1. Attachment cleaning
(1) The cleaning of the transformer bushing should be carried out from top to bottom. The cloth used for cleaning should be clean, especially without sticking to metal and conductors.
(2) Clean the radiator. Specific steps are as follows,
① Wash or boil with sodium hydroxide solution with a concentration of 3%~5%, then rinse and dry.
②The inside of the transformer should be flushed with qualified transformer oil until the outflowing oil is qualified.
③ Finally wash the exterior and repaint.
2. Refinish paint for corrosion of metal parts
(1) The exposed surfaces of the transformer oil tank, cooler and its accessories should be painted with light-colored paint.
(2) Before painting, the old film should be removed. The fuel tank and accessories can be soaked with 10% caustic soda or 20% trisodium phosphate solution, and then washed with clean water. When painting, the surface dirt can be used with 100# gasoline wipe.
(3) The method of painting can be spray paint, brush paint or spray paint, etc., depending on the site conditions.
(4) When painting, first coat the surface with primer, the paint film should not be too thick, generally about 0.05mm, it is required to be smooth and even, without flow marks, beads, wrinkles, etc., just apply a primer.
(5) After the primer is completely dry, it can be painted with medium gray alkyd paint. The thickness of the first paint film is about 0.05mm, and it is required to be smooth and even without flow marks and drooping balls. After the paint film is completely dry, apply the second paint. The thickness of the paint film should be 0.01~0.02mm. After painting, if there are spots and drooping beads, you can gently scrape them off with a bamboo piece or a knife, polish them with sandpaper, and paint them again.
(6) When painting, the air pressure should be 200-300kPa.
(7) When spraying paint, only one step is required.
After the transformer oil tank is painted, the elasticity of the paint film should be checked. The specific inspection method is as follows: a piece of paint film can be scraped off with a sharp knife.
3. Treatment method and process of oil leakage
(1) Before dealing with the leakage of the transformer, the exact leakage point must be found, and the large oil stains are often caused by only a small point. Transformer leakage is divided into welding leakage and sealing leakage. The method of dealing with welding leakage is repair welding; the method of dealing with sealing leakage is to improve the sealing quality, and the correct treatment of leakage should avoid using raw material method (such as resin, paint, soap, etc.) or binding method.
(2) When leakage is found in the upper part of the fuel tank, it is only necessary to discharge a small amount of oil to deal with it. When leakage occurs in the lower part of the fuel tank, it can be treated with oil, but the repair welding with oil should be carried out under the condition that the oil leakage is not obvious. The vacuum degree of negative pressure should not be too high, and it is best to have equal internal and external pressures to avoid absorbing molten iron. When the transformer with oil is welded and repaired, due to the convection effect of the oil, the heat generated by the electric welding can be quickly dissipated, the temperature near the welding point is not high, and the time of the repairing electric welding is short, and the oil does not contain a large amount of oxygen. Therefore, the oil is not easy to burn, and as long as the repair welding with oil is properly controlled, it will not cause a fire.
(3) When repairing the transformer, generally use a thinner electrode. When repairing with oil, gas welding is prohibited. When repairing welding with electric welding, attention should be paid to prevent penetration and ignition, and the welding part must be below 100mm of the oil level. When welding without oil, the oil traces near the welding should be wiped off. The welding time should not exceed 20 minutes each time, and the welding should be stopped for a few minutes to avoid burning and explosion.
(4) When repairing the pores with serious oil leakage, it can be blocked or riveted with iron wire before repairing welding.
(5) Cooling and protection measures should be taken when welding near the sealing rubber gasket or other vulnerable parts.
(6) When repairing the transformer in live operation, measures to prevent electric shock must be taken, and the gas protection must be adjusted to act as signal protection. After the operation is completed, the gas must be exhausted to restore the original working state of the heavy gas protection.
(7) It is best to use oil-free welding for radiators, heat pipes and thin-walled containers. If oil-based welding is necessary, special attention should be paid to preventing penetration.
(8) For the parts that are not easy to repair and weld, you can consider using a clamp to press the rubber pad as a temporary plugging measure
(9) The trachoma on the casting can be plugged with epoxy resin adhesive. When plugging the leakage, first clean the leakage point and rive the leak. After 15 minutes, the epoxy resin adhesive can be applied to the blisters of the casting, and then heated at 100~105℃.
(10) The pressure-bearing area of the sealing rubber pad should be adapted to the strength of the screw, otherwise it will not be pressed tightly. The oil meter rubber pad, butterfly valve rubber ring, box edge rubber strip, etc. should not be too wide. It is best to use rubber pads and rubber rings with circular cross-section.
(11) The crimping plane at the seal should be smooth and clean, and it is best to apply a layer of adhesive glue (such as polyvinyl chloride varnish, etc.) when placing the rubber pad.
(12) When replacing the rubber sealing ring of the oil plug with oil, the valves and channels at the inlet and outlet of this part should be closed, and the self-negative pressure should be maintained to prevent a large amount of oil from being released quickly.
(13) For small parts that are not easy to deal with oil leakage during the operation of the transformer, an oil sealing sleeve can be installed as a temporary measure.
(14) As far as possible, the sealing material should avoid the use of asbestos packing and cork pads. It is recommended to use plugging glue.