1. In order to protect the insulation properties of the step-up transformer as well as the insulating oil installed in its head, it is generally not allowed to open the observation window or screw off the fixing screws around, so as to prevent the moisture absorption or dust pollution, which reduces the insulation properties.
2. Check whether the lighting, heat radiation and dust-removing equipment around the step-up transformer are in good condition, and then wipe off the dust on the transformer body and porcelain bottle with clean cloth.
3. Check the load switch at high voltage side of the step-up transformer to ensure flexible operation and good contact. The transmission part shall be lubricated.
4. Open the high-voltage grounding knife switich and check that the grounding is in the disconnected position. After that, close the high-voltage load switch and let the step-up transformer pre-operate. And then remove the high-voltage side signboard. It should be noted that when disconnecting or closing the high-voltage load switch of the transformer, there must be more than two people on site.
5. Check the performance of the new lubricating oil to ensure that the insulation strength of the new oil is no less than 25000 V / 2.5 mm; and the insulation strength of the oil in the combination head should be more than 30000 V / 2.5 mm.
6. Use the 2400V megger to measure the insulation resistance (voltage to earth and phase-to-phase voltage) of high and low voltage coils of transformer to confirm that the insulation resistance meets the requirements (when the room temperature is 30 ℃, the high voltage side of 10kV transformer is greater than 20m Ω, and the low voltage side is greater than 13m Ω. Before the test, the grounding wire should be connected, and after the measurement, the discharge should be carried out.
7. The step-up transformer or the assembled headpiece must have good grounding wires. Ohmmeter should be used to measure whether the shell, console housing and external grounding wire are connected, and the grounding bolt shall be tightened.