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The Main Cause of Vacuum Reduction of Vacuum Circuit Breaker

Vacuum circuit breakers use the physical factors that eliminate arcs to continue so that arcs cannot be formed or sustained. The vacuum tube used in the vacuum circuit breaker maintains a certain degree of the vacuum so that when the dynamic and static contacts of the switch are breaking the load current, the arc cannot be generated or continued due to the absence or presence of a very little ionizable medium. The purpose of extinguishing the arc. However, the vacuum circuit breakers currently produced are not equipped with medium pressure blocking and other protections like the SF6 circuit breakers that are used more today, and there is no device for qualitative and quantitative monitoring of the vacuum degree characteristics. Therefore, the vacuum degree of the vacuum tube equipped with the circuit breaker is reduced in actual operation. It is impossible to be found in the fault, and the fault is recessive, and its danger is far greater than that of a dominant fault. Several reasons for the vacuum drop of the vacuum circuit breaker and the leakage of the vacuum tube are as follows.


1. The influence of the contact stroke of the vacuum circuit breaker


During installation or maintenance of the automatic circuit reclosers, the contact travel requirements in the product installation manual should be measured accurately, and the pull rod should be adjusted to prevent the travel from exceeding stroke and contact spacing. In actual operation, there are many accidents caused by improper adjustment of the overtravel of the circuit breaker, resulting in the rupture of the arc extinguishing chamber and the deformation of the conductive rod caused by the mechanical shock during the closing process of the circuit breaker. Choose 33kv auto recloser, recloser 24kv and 11kv auto reclosers.


2. The influence of the bounce of the vacuum circuit breaker


The contacts of vacuum circuit breakers are mostly flat butt-type structures, which inevitably produce different degrees of rebound phenomenon during the opening and closing operations. No matter the opening rebound or the closing rebound will bring harm to the operation: the bellows may undergo forced vibration and cracks may occur, causing the arc extinguishing chamber to leak air. The contact movement speed of the circuit breaker during opening and closing is relatively high, and the impact force at the end of the action is relatively high. If it is too large, it will cause bouncing, which may cause deformation of the contacts and conductive rods, and even cracks. If the vacuum circuit breaker connected to the capacitor bank has a closing bouncing, it will also cause damage to the capacitor.


3. The influence of vacuum circuit breaker opening and closing speed


The opening and closing speed of the circuit breaker plays a certain role in the arc extinguishing of the vacuum circuit breaker, and also determines the service life of the vacuum circuit breaker. Therefore, the opening and closing speed should be measured before the circuit breaker is put into operation so that some problems in product quality and debugging can be found in time. On the one hand, it prevents the opening and closing speed from being too large, and when the contact of the circuit breaker ends, the mechanical collision is violent, which makes the arc extinguishing chamber produce more serious vibrations.


4. The influence of vacuum circuit breaker buffer


The buffer stroke should be carefully checked, there should be no deformation damage or excessive compression, and a buffer allowance must be left. For some oil-filled buffers, the oil level of the buffer should be checked regularly, and the oil should be replenished in time.


5. The influence of vacuum circuit breaker operating mechanism capacity


In recent years, some circuit breakers have been equipped with a "permanent-magnet operating mechanism" for the operating mechanism modified to adapt to different installation spaces. Equipped with different types of operating mechanisms, during installation or transformation, attention should be paid to the operating distance of the operating transmission rod. If the capacity is too large, it will cause a serious impact on the arc extinguishing chamber, causing damage to the bellows of the vacuum interrupting chamber and directly affecting the vacuum. The service life of the circuit breaker makes the vacuum degree of the circuit breaker decrease faster.


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