【technology】main Transformer Epoxy Resin Bushing Fault Analysis And Maintenance Method

The substation installation team dismantled the #1 main transformer epoxy bushing and transported it back to the company warehouse. The initial maintenance plan was to replace the insulating oil inside epoxy resin bushing. Drain the oil from epoxy resin cast bushing, evacuate, and refill. After the above treatment, the high-voltage test was carried out. The test data after the first maintenance was not obvious. The insulation resistance of the end screen of epoxy bushing manufacturerB and C phases to the ground still did not meet the requirements of the test standard. Is there a flaw in the test method or is the internal structure of epoxy bushing for transformer also damp, resulting in unsatisfactory dielectric loss measurement? When measuring the dielectric loss factor of the bushing, pay close attention to its placement position, because the capacitance of the main transformer bushing is very small. When the placement position is different, the influence of the scattered impedance of the measuring electrode and the high-voltage electrode on the surrounding equipment, frame, wall and ground that are not fully grounded will cause the actual measurement results of the bushing to be very different. Different positions will have different effects, and there will often be very different measurement results. Therefore, when measuring the dielectric loss of the bushing or other tests of the bushing, it is required to place the bushing vertically on the bushing stand with grounding measures in place. The bushing cannot be placed horizontally or hung up with an insulating rope for measurement, otherwise the measurement data will be inaccurate. Therefore, the test personnel checked and reviewed the links of the test, and there were no problems in each link.
The effect of simply replacing the insulating oil inside the bushing is not ideal, and the internal structure of the bushing must be further dried. After comprehensive consideration of all aspects, it was finally decided to dismantle the bushing, put the bushing capacitor core together with the conductor into the oven, and heat it while vacuuming it, implementing a two-pronged strategy. Therefore, secondary maintenance work was carried out.