After vacuum circuit breaker after long-term use, once one of the following happens, it shows a vacuum interrupter may have been the end of its life, consider replacing.

(1) of storage or use of a vacuum interrupter of the product exceeds the predetermined period (from the date of the factory vacuum interrupter), domestic vacuum interrupter period is generally about 20 years.

(2) vacuum of the vacuum interrupter chamber is reduced to 1.33 × 10 ^-2 Pa (available magnetron vacuum gauge conditions), if the glass envelope is vacuum interrupter, when the metal was observed when the shield significant changes color, degree of vacuum should be checked immediately.

(3) the wear amount of accumulated vacuum interrupter contacts exceeds a predetermined value use products, products are generally made of 3mm, most products in the movable contact rod is provided with warning signs allowable wear amount (point or line), when the amount of wear when accumulated more than 3mm, after closing unseen warning signs.

(4) rated short-circuit current cut-off frequency up to more than the number of electrical product life.

(5) mechanically combined, sub-operation number exceeds a predetermined value product manual.