Personnel actions in case of 6 (10) kV transformer accidents

Personnel who maintain an electrical installation, for example, a 6 (10) / 0.4 kV substation, often receive a message from the user that the voltage has disappeared in the 0.4 kV electrical network. The first thing to do in this case is to arrange an inspection of the electrical equipment. In this case, it is necessary to observe the rules of the instructions for the maintenance of electrical installations.

First of all, you need to check the presence of voltage in the 0.4 kV switchboard, the position of the circuit breakers of the outgoing lines and the transformer bushing. If all breakers are in the on position and there is no voltage at the same time, it is necessary to check the transformer equipment. It is possible that the switchboard (section) was tripped as a result of a transformer failure.

During an external inspection, the operating personnel of the electrical installation must perform the following actions:

— in the 6 (10) kV switchgear, check the closed position of the oil switch or other switching device through which the voltage is supplied to the power transformer;

— produce inspection of power transformersfrom which the consumer receives electrical energy, for the absence of external damage, as well as for the absence of external noise, crackling, radiation or leakage of transformer oil.

If it was not possible to identify the fault by external inspection, the voltage of the transformer is suitable, then the presence of voltage in all phases of the 0.4 kV busbars in the switchgear should be checked.

The absence of voltage on one of the phases or on all phases of the 0.4 kV switchgear indicates that the equipment (input switch, busbar, cable, etc.) is damaged in the electrical circuit. In this case, the power transformer must be removed for repair by disconnecting and earthing from all sides from which voltage can be applied. The preparation of the workplace must be carried out in accordance with the requirements of the current regulations.

If the cause of the lack of voltage on one of the phases in the 0.4 kV switchgear is blown fuses (high voltage or low voltage), then the fuses must be replaced. Before putting the power transformer into operation, you must do insulation resistance measurementand its coils.

After replacement or repair of damaged equipment, as well as after establishing other reasons for the lack of voltage in the 0.4 kV buses, the power transformer is turned on under voltage, without load.After checking the equipment (power transformer, busbars, switching devices, connecting cables), in the absence of external noise, transformer oil leaks, the power transformer is switched on under load. Turn on the power transformer that is disabled by the action relay protection, without identifying the reason for deactivation, is strictly prohibited.