What are the basic requirements for a qualified vacuum circuit breaker?

Vacuum circuit breakers must withstand operating voltages and various overvoltages (including switching overvoltages and atmospheric overvoltages) during operation. Their insulation system must ensure it does not break down under these voltage conditions.

Specific requirements include:

Power frequency withstand voltage: For 12kV products, the inter-pole and pole-to-ground withstand voltages should be 42kV, and the inter-break withstand voltage should be 48kV.

Lightning impulse withstand voltage: The inter-pole and pole-to-ground withstand voltages should be 75kV, and the inter-break withstand voltage should be 84kV.

Even in the open state, the vacuum interrupter breaks must have sufficient insulation capacity.

Circuit breakers must be able to operate stably when carrying rated current for extended periods and possess a certain overload capacity.

Temperature Rise Control: Under rated current, the temperature rise of each part must not exceed the specified value.

Loop Resistance: The DC resistance of the main circuit should meet the product technical specifications (e.g., ≤60μΩ for 12kV/1250A products).

The DC voltage drop method (current not less than 100A) should be used to measure the resistance of the conductive circuit.

Impact force during normal opening and closing

Electrodynamic force when interrupting short-circuit current

Various internal stresses of the operating mechanism

Affected by external forces such as earthquakes

Must be able to reliably interrupt the rated short-circuit current and have a certain electrical life (e.g., 20-50 full-capacity interruptions).

Should be able to close the rated short-circuit closing current (peak value).

Should be able to open and close capacitive currents (e.g., switching capacitor banks) and small inductors. Special loads such as current

Mechanical Lifespan: Typically required for 10,000-30,000 operations

Electrical Lifespan: Required number of full-capacity short-circuit current interruptions (e.g., 20-50 times)

Vacuum Lifespan: Storage period and allowable wear thickness of the vacuum interrupter

Altitude: Standard products are suitable for ≤1000m, high-altitude products can reach 4600m

Ambient Temperature: -25℃～+40℃

Humidity: Daily average relative humidity ≤95%

Seismic Intensity: Not exceeding 8 degrees

Reliable operation and rapid response

Insulation resistance of opening and closing coils should not be less than 10MΩ

Smooth electric and manual operation should be both smooth

Interlocking functions such as anti-pumping and anti-misoperation are required