Japan began to develop from 1960 VCB (vacuum breaker), beginning in 1970 1976 officially put on the market, VCB has accounted for the Japanese medium voltage circuit breakers market 50%, 20 years after 1990 has accounted for more than 70%, and in 2007 accounted for the total number of 80%, with absolute advantage over other circuit breaker. Now Japan produces about 250 thousand VCB each year.

The progress of vacuum circuit breaker in Japan is reflected in the aspects of material, technology, design and so on.

(1) vacuum interrupter contact. Starting from the copper lead contact material, 20 years ago into a copper chromium contact material. In order to improve the performance of the material, the particle size and micro additives were studied.

(2) insulating shell of vacuum interrupter. The initial use of glass shell, after the ceramic shell into the mainstream. At present, in order to achieve high voltage, the improvement of the electric field of brazing metal is carried out.

(3) bellows of vacuum interrupter. Stainless steel and special steel. In order to extend the life of the machine, the research on the shape of bellows is carried out, and the bellows can be rotated in addition to the telescopic movement.

(4) VCB insulating material. Insulating materials used in VCB polyester and epoxy resin. In recent years, in order to improve the adhesion between the epoxy resin and ceramic, adding spherical silica particles and core-shell rubber particles in epoxy resin.

(5) high voltage of vacuum interrupter. VCB has long been the mainstream of the 40.5 kV voltage rating. Newly developed 145 kV single fracture and double kV fracture of 170 VCB. According to the survey, the Japanese transmission system using 72.5 kV above the level of vacuum circuit breaker for the 3350 units, mainly by the production of three manufacturers.

(6) no grease VCB. In order to solve the problem that the VCB failure rate is more than half of that caused by the curing of the grease, there is no electrolytic NiP plating on the gear, and the non lubricated products with solid lubrication bearings.

(7) vacuum sealing process improvement. In the initial stage of development, the vacuum arc extinguishing chamber is brazed and then discharged. Since 2000, the vacuum interrupter has been used for the first time of the same time, which can improve the vacuum and improve the efficiency.

(8) high precision brazing. The vacuum interrupter in high temperature brazing, due to expansion and contraction of parts, deformation than the original shape when tens of MM returned to normal temperature, through the improvement of material and heating method, developed the deformation size could be required to position control in high precision brazing below 0.1 mm.