Notes on the use of dry-type transformers and maintenance methods
Notes on the use of dry-type transformers and maintenance methods
1, Put in the spare transformer, disconnect the circuit breaker on the low voltage side of the dry-type transformers for maintenance that take off the operation insurance of the control power and hang the "No closing" sign at the switch handle.
2, Disconnect the circuit breaker on the high voltage side of the overhaul transformer, close the grounding switch, discharge the transformer, lock the high voltage cabinet and hang the "no closing" sign at the switch handle.
3, Dry-type transformer maintenance, the first thing need to clean the porcelain casing and shell, followed by checking the shell, gasket, porcelain casing has no rupture, discharge traces or rubber pad has no aging, cable and bus bar has no deformation phenomenon. There is a rupture should be replaced.
4, Check whether the busbar contact surface need to keep clean, the contact surface should be removed from the oxide layer and coated with power compound grease.
5, Check whether the grounding of the transformer is good or not and whether the earth wire is corroded, the corroded serious should be replaced or not.
6, Tighten the lead terminals, pins, grounding screws, connecting bus bar screws, such as loose should remove the screws, or use a fine flat file to lightly file the contact surface, or replace the spring washers, screws, until the contact is good.
7, Clean the dust around the dry-type transformers the accessories, check whether the fire-fighting facilities and ventilation system are good or not.
8, Disconnect the high-voltage side of the grounding switch and lock the high-voltage open joint pectus with 2500V shaking table to determine the insulation resistance. And compare with the factory measured value of the dry-type transformers, insulation resistance should not be lower than 70% of the original data at the factory, if not qualified should be reported in time to deal with.
9, Close the grounding switch on the high voltage side again and let the dry-type transformers discharge.
10, Check that there are no tools left in the dry-type transformers room and transformer and evacuate the site.
11, Connect the low-voltage side of the circuit breaker control power operation insurance which re-hang the "no closing" sign for preventing the transformer back to send power.
12, Disconnect the high-voltage side grounding switch, check again the dry-type transformers site and low-voltage side of the control line, no error, close the transformer high-voltage side of the circuit breaker, let the transformer test run to take down the high-voltage side of the sign.
13、Make detail maintenance trial and make records.
Second, safety precautions
1, Test insulation resistance must be carried out by two men.
2, Before charging and discharging the dry-type transformers, touching is strictly prohibited.
3, Prevent back-feeding to the transformer and transformer to the running busbar.
4、The maintenance person should wear insulated shoes and insulated gloves for operation.
5、Forbid to close the gate by mistake.