1.1 Fault phenomenon

Vacuum circuit breaker in the vacuum bubble to open the current and interrupt the arc, and the vacuum circuit breaker itself does not have qualitative and quantitative monitoring vacuum characteristics of the device, so the vacuum degree reduction fault for the hidden fault, the degree of danger is much greater than the explicit fault.

1.2 Cause analysis

The main reasons for vacuum degree reduction are as follows:

(1) The material or production process of vacuum bubble has problems, and the vacuum bubble itself has tiny leakage points;

(2) There is a problem with the material or production process of the waveform tube inside the vacuum bubble, and there is a leakage point after multiple operations;

(3) The split vacuum circuit breaker, such as the vacuum circuit breaker using electromagnetic operation mechanism, is operated at a relatively large distance from the operating linkage, which directly affects the characteristics of the switch such as simultaneous, bouncing and over-travel, and makes the vacuum degree decrease faster.

1.3 Fault hazard

The decrease of vacuum degree will seriously affect the ability of vacuum circuit breaker to open overcurrent, and lead to a sharp decline in the service life of the breaker, which will seriously cause the switch to explode.

1.4 Treatment method

(1) During regular outage maintenance of the circuit breaker, the vacuum bubble must be tested qualitatively using a vacuum tester to ensure that the vacuum bubble has a certain vacuum level;

(2) When the vacuum level decreases, the vacuum bubble must be replaced and the characteristics tests such as stroke, simultaneous and bounce must be done.

1.5 Preventive measures

(1) When choosing vacuum circuit breaker, you must use mature products produced by reputable manufacturers;

(2) select vacuum circuit breakers with integral body and operating mechanism;

(3) when operating personnel inspect, they should pay attention to whether there is discharge phenomenon outside the vacuum bubble of the circuit breaker, if there is discharge phenomenon, the vacuum bubble vacuum test result is basically unqualified, and should be promptly shut down and replaced;

(4) When inspectors carry out outage maintenance work, they must carry out the same period, bounce, travel, over travel and other characteristic tests to ensure that the circuit breaker is in good working condition.