1. The cycle of minor repairs of transformers
(1) The main transformer and the service transformer of the power plant shall be installed at least once a year.
(2) Distribution transformer once a year.
(3) For transformers installed in particularly polluted areas, the minor repair period should be specified in the site regulations.
2. Transformer minor repair projects
(1) Inspect and remove discovered defects.
(2) Check whether the connection bolts of the casing leads are loose and whether the joints are overheated.
(3) Check whether the oil level of the oil conservator is normal, whether the oil level gauge (oil level gauge) is in good condition and clean, and discharge the oil in the sewage collection basin.
(4) Overhaul the transformer oil protection device and the oil drain valve.
(5) Overhaul the cooler, oil conservator, safety air passage and its protective film. Check whether the explosion-proof membrane of the safety airway is in good condition, and remove the dust, snow and other debris deposited in the valve cover of the pressure relief valve.
(6) Check the casing seal, the top connection cap sealing gasket, check the porcelain insulation and clean it.
(7) Overhaul and test various protection devices, measuring devices and operation control boxes.
(8) Check the operation control circuit of the on-load tap-changer, the transmission part and its contact action, and clean the inside of the operation box
(9) The oil-filled bushing and body are supplemented with transformer oil.
(10) Overhaul and painting of paint and accessories.
(11) Check the respirator and replace the discolored desiccant.
(12) Clean the cooling system, check whether the radiator sees oil, whether the cooling fan, submersible pump, and water pump work normally, and whether there is oil or water leakage in the oil cooler.
(13) Take oil samples from the transformer body, oil-filled bushings and oil purifiers for simplified tests, and take oil samples from the transformer body and capacitive bushings for chromatographic analysis.
(14) Check the thermometer for measuring the oil temperature of the upper layer.
(15) Conduct electrical tests for specified items.
3. During on-site maintenance, the key maintenance content
(1) Check whether the fastening bolts of the conductive bar are loose; whether the joints of the conductive bar are overheated; if there is a temperature-indicating wax sheet attached, check whether it is melting or is about to be melted.
(2) Clean the porcelain skirt of the casing, check whether there are discharge marks on the surface of the porcelain skirt, and whether the surface is cracked or damaged.
(3) Clean the case of the transformer and check whether there is any leakage of oil. If there is, try to eliminate it as much as possible.
(4) Check whether the film of the explosion-proof pipe is in good condition
(5) Check whether the equipment of all cooling systems is in good condition. For example, for self-cooling transformers, the dust accumulation on the surface of the radiator should be cleaned, and the welds should be checked for oil leakage; for air-cooled transformers, in addition to the same inspection items as self-cooled transformers, it is also necessary to check whether the working condition of the cooling fan is normal; for forced oil circulation air-cooled transformers, it is also necessary to check whether the working condition of the submersible oil pump is normal; for forced oil circulation water-cooled transformers, it is necessary to check whether the working conditions of the submersible oil pump and the cooling water pump are normal, and whether there is oil leakage and water leakage on the surface of the cooler.
(6) Check whether the gas relay is leaking oil, whether the opening and closing of the valve is flexible, whether the action is correct and reliable, and whether the insulation resistance of the control cable and the relay contact is good.
(7) Check whether the oil level of the oil conservator is normal. The surface of the oil level gauge should be wiped clear and transparent for easy observation. The dirty oil in the dirt collection box at the bottom of the oil conservator should be released, and at the same time, check whether the moisture absorbent of the moisture absorber is invalid.
(8) For each part of the transformer, such as the body, oil purifier, oil-filled bushing, etc., oil samples should be taken for electrical insulation strength test and chemical simplified test.
(9) The thermometer for measuring the oil temperature of the upper layer should be removed for calibration, and check whether the temperature measuring tube is filled with transformer oil.
(10) Do transformer insulation preventive tests.