Analysis of common causes of failure in high voltage switchgear

High voltage switchgear is a very important electrical equipment in power systems. Deterioration of the operating state of the switchgear is one of the causes of the failure of the power system. Analysis of the reasons for the failure of high-voltage switchgear, mostly in insulation, electrical and mechanical aspects.

First, refused to move or malfunction

This kind of fault is the main fault of the high voltage switchgear, and the reasons can be divided into two categories. One type is caused by the mechanical failure of the operating mechanism and the transmission system. The specific performance is that the mechanism is stuck, the parts are deformed, displaced or damaged, the core of the closing and closing is loose, the card is loose, the shaft pin is loose, and the tripping is unsuccessful. The other type is caused by electrical control and auxiliary circuit, which is characterized by poor contact of secondary wiring, loose terminals, incorrect wiring, burn-off of the closing and closing coil due to poor mechanism or switch, auxiliary switch failure, and operation. Power supply, closing contactor, micro switch, etc.

Second, breaking and closing faults

This type of fault is caused by the main body of the circuit breaker. For the oil-less circuit breaker, the main performance is short-circuit of the fuel injection, burnout of the arc-extinguishing chamber, insufficient breaking capacity, and explosion at the time of closing. For the vacuum circuit breaker, it is characterized by air leakage of the arc extinguishing chamber and the bellows, reduction of vacuum, re-ignition of the capacitor capacitor group, and cracking of the ceramic tube.

Third, insulation failure

The insulation level is to correctly handle the relationship between various voltages (including operating voltage and various overvoltages) acting on the insulation, various voltage limiting measures, and dielectric strength. Strive to make products safe and economical, and get the best economic benefits. In the insulation failure, the main performance is the external insulation to the ground flashover breakdown, the internal insulation to the ground flashover breakdown, the phase insulation flashover breakdown, the lightning overvoltage flashover breakdown, the porcelain bottle casing, the capacitor casing flashover , pollution flash, breakdown, explosion, lifting rod flashover, CT flashover, breakdown, explosion, porcelain bottle breakage.

Fourth, current carrying fault

The main cause of the current-carrying fault occurring at the voltage level of 72~12KV is that the contact of the switchgear isolation plug causes the contact to be melted.

5. External forces and other faults

Including foreign body impact, natural disasters, small animal short circuits and other unknown external forces and unexpected failures.