The coil of the oil-immersed transformer is an important tool for the oil-immersed transformer. The coil of the oil-immersed transformer usually has one or the other problem. The coil of the oil-immersed transformer is also in the process of maintenance. Need to pay attention to maintenance, common maintenance oil-immersed transformer coil requires everyone to pay attention to the following operations:
(1) First check whether the winding insulation is aging and damaged. Generally, use your fingers to touch the surface of the winding insulation and observe the changes. If the insulation color is slightly dark and will not be broken due to finger pressure, it indicates that the insulation is in good condition; on the contrary, the insulation will produce small cracks or insulation after pressing with your fingers The texture is hard and brittle, and the color is dark, indicating poor insulation, and further inspection is required.
(2) Measure the insulation resistance value of the winding with a megohmmeter, and compare this value with the insulation resistance value measured for the first time before the oil-immersed transformer is put into operation. If the insulation resistance of the winding is lower than the manufacturer's test during operation If the value is 70%, the insulation condition of the winding of the oil-immersed transformer is considered to be poor; if the decrease in insulation resistance is not caused by damp winding, the insulation medium test and withstand voltage test can be carried out to further judge the insulation condition of the winding, and then do deal with.
(3) There are two situations for oil-immersed transformers that are shut down by the action of a gas relay: one is a short circuit between winding turns or layers. You can first measure the DC resistance of each phase separately and compare the test data for any difference. Then pass the rated voltage on the winding to do a no-load test. If there is a short circuit between turns or layers, the short-circuit turns will generate heat and smoke, which will enlarge the damage. If the fault cannot be eliminated by repairing methods, part or all of the windings must be replaced. The second is the failure of winding disconnection. First of all, the DC resistance of each phase winding should be tested. After the numerical comparison, the faulty phase can be basically determined, and the broken wire can be found to repair or replace part of the winding coil.
The above are the main operating methods and methods for coil maintenance common in oil-immersed transformers
