Arc-extinguishing chamber explosions are among the most serious equipment accidents in power systems. The direct cause is usually arc reignition-after the current crosses zero, the dielectric insulation strength of the arc gap is insufficient, leading to a re-breakdown by the recovery voltage. The instantaneous release of enormous energy is enough to destroy the arc-extinguishing chamber and affect surrounding equipment.
Switching Capacitor Banks: High-Risk Operations with Capacitive Loads
When switching capacitor banks, the break point must withstand a high recovery voltage with a superimposed DC component. Reignition can generate 3-5 times the operating overvoltage, easily triggering a chain reaction of explosions in multiple capacitor banks on the same busbar. The voltage is higher when the system is lightly loaded or unloaded late at night, multiplying the operational risk.
Switching Long Unloaded Lines: Gradual Accumulation of Energy
When disconnecting unloaded lines, if the arc-extinguishing capacity is insufficient, the arc may reignite repeatedly within half a cycle. The overvoltage accumulates gradually to 3-4 times the phase voltage, causing cumulative mechanical impact on the arc-extinguishing chamber wall, ultimately inducing structural collapse. Secondary switching after a failed reclosing is particularly dangerous.
Hidden Equipment Defects: Vacuum Deterioration and Mechanical Failure
Leakage in the vacuum interrupter causes a precipitous drop in insulation strength, leading to breakdown without warning even under normal operating voltage. Insufficient gas pressure in the SF₆ circuit breaker reduces the tripping speed, causing arc-extinguishing failure. Residual heat accumulates rapidly, potentially igniting the interrupter within seconds.
Prevention Measures: It is strictly forbidden to switch capacitors under no-load conditions on the busbar. Regularly monitor vacuum and gas pressure. Install RC absorption devices or zinc oxide surge arresters on the load side as overvoltage backup protection to reduce extreme risks to a controllable range.
Shaanxi West Power Tongzhong Electrical Co., Ltd.
Our address
Nanpo Village, Chencang Avenue Jintai District Baoji City, Shaanxi Province, China.
Phone Number
+86 18091765882(WhatsApp/Wechat/facebook)
