What to do if the vacuum level of a vacuum circuit breaker drops? - Blog

When the vacuum level of a vacuum circuit breaker drops, power must be immediately cut off, the vacuum interrupter replaced, and the mechanical characteristics test repeated. A decrease in vacuum level is a latent fault; if not addressed promptly, it can severely affect breaking capacity and even cause the circuit breaker to explode. Specific handling and detection steps are as follows:

1. Fault Diagnosis and Detection

Visual Inspection: During routine inspections, operators should observe for any discharge phenomena outside the vacuum interrupter. If discharge is present, it can be generally determined that the vacuum level is unqualified, and power must be cut off and the circuit breaker replaced immediately.

Instrument Testing: During periodic power outage maintenance, a vacuum level tester must be used to qualitatively test the vacuum interrupter to ensure that its vacuum level remains within the acceptable range of 10⁻⁴ to 10⁻⁶ Pa.

Withstand Voltage Confirmation: If the test reveals that the vacuum level drops beyond the limit, further confirmation through a power frequency withstand voltage test is required.

2. Core Handling Methods

Replacing the Vacuum Bulb: Once a decrease in vacuum is confirmed, the only solution is to replace the defective vacuum bulb (vacuum switch tube).

Adjusting Mechanical Characteristics: After replacing the vacuum bulb, it is essential to readjust and rigorously perform tests on characteristics such as stroke, synchronization, bounce, and overtravel to ensure the switch data is up to standard and restore the equipment to a safe operating state.

3. Cause Analysis and Prevention

A decrease in vacuum is usually caused by the following mechanical or manufacturing factors, requiring targeted prevention in daily operations:

Eliminating Mechanical Bounce and Impact: Contact bounce during opening and closing operations or excessively fast opening and closing speeds can cause severe vibrations, leading to cracks in the bellows of the arc-extinguishing chamber and leakage.

Optimizing the Operating Mechanism: If the operating linkage distance is too large or the operating mechanism capacity is inappropriate, it can easily cause damage to the arc-extinguishing chamber. Therefore, mature products with integrated operating mechanisms should be prioritized.

Regular Maintenance of the Buffer: If the buffer is deformed, damaged, or excessively compressed, it must be taken out of service. Regular inspection and lubrication are necessary to prevent damage to the arc-extinguishing chamber due to buffer failure.

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VTZ-12 Vacuum Circuit Breaker