Overview

When a fault occurs in the T-connected branch line of  a 12kV overhead distribution line or in the end user, the protection action time limit of the incoming switch cannot be reasonably adjusted with the protection time limit of the outgoing switch of the substation, which will cause the outgoing switch of the substation to trip. If the nature of the fault is permanent, the reclosing of the substation will fail, and a local fault in the boundary of a medium-voltage user will cause the entire 12kV distribution line to be shut down. If an outdoor boundary circuit breaker is installed at the T-connection or the user end (responsibility boundary point), after judging and confirming that a fault (overcurrent, short circuit, single-phase grounding, etc.) has occurred in the user boundary, the fault will be automatically isolated, which can ensure normal power supply to users in non-fault areas.

Model meaning

Environmental conditions

◆ Ambient temperature: not higher than +40T, not lower than -40C;

◆ Relative humidity of air: daily average value is not more than 95%, monthly average value is not more than 90%;

◆ The altitude shall not exceed 2000 meters;

◆ Wind pressure does not exceed 700Pa (equivalent to wind speed 34m/s);

◆ The earthquake intensity does not exceed 8;

◆ Places free from fire, explosion, severe pollution, chemical corrosion and severe vibration.

Main technical parameters of circuit breaker

Appearance and installation dimensions (mm)

The application of ZW32-12F outdoor high-voltage intelligent demarcation vacuum circuit breaker (watchdog) on 12kV feeder overhead lines can avoid joint power outages of fault-free lines, reduce the scope of fault power outages, shorten the power outage time of users, and protect the safe operation of the main network. It also has fault detection function, protection control function and communication function, and can automatically cut off single-phase grounding faults and automatically isolate interphase short circuit faults. The installation point is used at the responsibility demarcation point of the user incoming line of the 12kV distribution line, and can also be applied to the branch line connection that meets the requirements.