Make the standby transformer put into operation, and disconnect the low-voltage side circuit breaker of the overhauled box transformer, remove the operation insurance of the control power, and suspend the "closing" sign at the handle of the switch.
Disconnect the circuit breaker of the high voltage side of the transformer, close the grounding switch, fully discharge the transformer, lock the high voltage cabinet, and hang the "no closing" sign on the switch handle.
Check whether the grounding of the transformer is good, the ground wire is corroded, and the serious corrosion should be changed.
For the maintenance of box type frequency converter, first sweeps the porcelain bushing and shell. Secondly, check whether the shell, gasket, porcelain bushing has breakage, discharge trace or whether the rubber pad has aging, whether the cable and bus bar are deformed, and there should be a replacement for the ruptured.
Clean the dust around the transformer and the accessories, and check whether the fire protection facilities and the ventilation system are good.
Check whether the contact surface of the busbar is clean, the contact surface should be removed from the oxide layer and applied to the power compound grease.
Fastening the lead terminal, pin, earthing screw and connecting bus screw. If there is a loosening, the screw should be removed or use a smooth file to smooth the contact surface, or replace the spring washer, screw, until contact is good.
Connect the low-voltage side circuit breaker to control the power operation insurance, and put up the "no closing" sign.
Disconnect the grounding switch on the high voltage side and lock the high pressure open joint, and measure the insulation resistance with a 2500 V meter.
The insulation resistance should not be less than 70% of the original data of the original time of the factory. If it is unqualified, it should be reported in time.
Close the grounding switch on the high side again to discharge the transformer.
Check for legacy tools and evacuate site.
Disconnect the high side grounding switch, inspect the site of the transformer and low voltage side of the line of control, after that, close the transformer's high voltage circuit breaker, let the transformer runs on trial, remove the sign of high pressure side.