Operating Hanism Failures Account For A High Proportion: How To Prevent Vacuum Circuit Breaker Failure To Operate - News

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The proportion of malfunctions in the operating mechanism is high

According to CIGRE statistics, about 70% of high-voltage circuit breaker failures are mechanical failures, and operating mechanism failures account for more than 60% of mechanical failures. Although vacuum circuit breakers have no risk of gas leakage, their operating mechanisms, transmission linkages, and trip components will wear, jam, or suffer spring fatigue as the number of operations increases. Once they fail to open during a fault, they may cause cascading trips or even equipment burnout. Preventing failure-to-operate risk should focus on the following aspects.

Core Method-Mechanical Property Testing

First, mechanical characteristic testing should be taken as a core measure. In accordance with GB/T 1984 and DL/T 403, opening and closing times, three-phase simultaneity, travel curves, opening and closing speeds, and bounce time should be measured periodically. Prolonged opening time often indicates insufficient trip force, while excessive simultaneity error may cause open-phase interruption. State Grid Corporation of China's Eighteen Major Anti-Accident Measures for Power Grids also explicitly require strengthening mechanical characteristic testing of circuit breakers.

Enhance monitoring of coil current and the control circuit

Second, coil current and control circuit monitoring should be strengthened. Distortion in the opening and closing coil current waveform can reflect mechanism jamming, abnormal iron core travel, or inter-turn short circuits in the coil; poor contact of auxiliary switches, loose wiring, and supply voltage fluctuations can also cause mechanism failure to operate. For circuit breakers in service, wiring should be tightened, and coil resistance and insulation should be tested during outages.

Environmental Protection and Special Inspections

Third, environmental protection and special inspections should be carried out effectively. The mechanism enclosure should remain sealed, and heating and dehumidifying devices should be installed to prevent condensation and corrosion. For spring mechanisms, focus should be placed on checking spring fatigue and latch wear; for permanent magnet mechanisms, attention should be paid to permanent magnet demagnetization risk and capacitor energy storage status.

Arrange for maintenance

Finally, maintenance should be arranged based on the number of operations and equipment condition, rather than blindly disassembling and inspecting according to a fixed cycle. Only by combining mechanical characteristic testing, circuit monitoring, and environmental protection can the risk of failure to operate caused by operating mechanism faults be effectively reduced.