General knowledge and skills of distribution transformer maintenance
Writer： Hengfeng you electric Time：2023-04-18 views：times
General knowledge and skills of distribution transformer maintenance
The maintenance of distribution transformer is to ensure its normal and safe operation after maintenance. The power is safe and stable, and the transformer in operation or shutdown shall be maintained once a year. When it is put into operation, it shall be checked and maintained before operation.
before transformer maintenance, put in the standby transformer, disconnect the circuit breaker at the low-voltage side of the transformer for maintenance, remove the operation insurance for controlling the power supply, disconnect the circuit breaker at the high-voltage side of the transformer for maintenance during transformer maintenance, close the grounding switch, lock the high-voltage cabinet after sufficient discharge of the transformer, and hang the "stop closing" sign at the switch handle, For the maintenance of dry-type transformer, firstly, carefully clean the porcelain bushing and shell, and then check whether the shell and gasket are cracked, whether the discharge imprint or the rubber pad is aging, whether the cable and bus are deformed, replace and update them in time, check whether the bus contact surface is clean, and remove the oxide layer on the contact surface and apply electric compound grease.
during transformer maintenance, check whether the grounding of the transformer is good and whether the ground wire is corrupt. If the corruption is serious, replace it; Fasten lead terminals, pins, grounding screws and connecting bus screws; During maintenance, be sure to clean the dust around the transformer and accessories, and check whether the fire-fighting facilities and ventilation system are in good condition. Check whether there is any problem with the cooling fan and whether the temperature controller is defective. Disconnect the grounding switch on the high-voltage side, lock the high-voltage disconnecting joint bar, and measure the insulation resistance with a 2500V megger. Compared with the measured value of the transformer before leaving the factory, the insulation resistance shall not be less than 70% of the original data when leaving the factory. If it does not meet the standard, it shall be reported for disposal immediately, close the grounding switch on the high-voltage side again, let the transformer discharge, check whether there are left tools in the transformer chamber and transformer, evacuate the site, and electricians shall make detailed records of transformer maintenance and commissioning.
precautions for transformer maintenance
I. prevent overload operation of transformer: if it is overloaded for a long time, it will cause coil heating and gradually aging insulation. When the transformer is running, its coil and iron core produce copper loss and iron loss. These losses become heat energy, which increases the temperature of the core and coil of the transformer. If the temperature exceeds the allowable value for a long time, the insulation will gradually lose mechanical elasticity and aging the insulation.
2、 Check the exhalator and replenish oil regularly if there is a lack of oil. Monitoring the upper oil temperature during the operation of the transformer can not ensure the safe operation of the transformer. It is also necessary to monitor the temperature difference between the upper oil temperature and the cooling air - that is, the temperature rise. The difference between the transformer temperature and the ambient air temperature is called the temperature rise of the transformer
III. reasonable capacity during normal operation, the power load borne by the transformer shall be about 75-90% of the rated capacity of the transformer (hengfengyou electric recommends 80% capacity, and the operation energy consumption of the transformer will be the lowest).
IV. overload includes normal overload and accident overload. Normal overload is caused by the increase of user's power consumption under normal power supply. It will raise the transformer temperature, accelerate the aging of transformer insulation and reduce the service life. Therefore, overload operation is not allowed under normal circumstances. Under special circumstances, the transformer can operate overload in a short time, but it shall not exceed 30% of the rated load in winter and 15% of the rated load in summer. In addition, the overload capacity of the transformer shall be determined according to the temperature rise of the transformer and the regulations of the manufacturer. When an accident occurs in the power system or user substation, in order to ensure the continuous power supply to important equipment, the transformer is allowed to operate under overload for a short time, that is, accidental overload. Accidental overload will cause the coil temperature to exceed the allowable value. Therefore, the insulation will age faster than normal conditions. However, there are few opportunities for accidental overload. In general, the transformer operates under load, so short-term overload will damage the insulation of the transformer. The time and multiple of accident overload shall be implemented according to the regulations of the manufacturer.
