History of vacuum circuit breaker and recent development in Japan

Vacuum circuit breaker(VCB) have been developed and applied widely to Japan to meet her requirements of increasing energy consumption and also national security of various aspects. As a result, for ultimate examples, a 168kV two break porcelain type or a 100kA one break VCB have already appeared in the Japan and world-wide markets. Especially, VCB interrupts current in a vacuum, and, in its nature, a recycling of material and harmless to human body have been realized and also no global warming effect would be expected. Energy is extremely essential and important for human daily life, and at this moment, a future trend of VCB must be discussed widely. In this paper, the results of the recent development in Japan will be reviewed and the reflection of the results will be stated and the subjects of engineering in the 21st century will be discussed. These must include recycling, harmless to human body and fireless natures of VCB's, and it will be demonstrated that the developmental works of VCB is being very wonderfully conducted in Japan.