Abstract
The national voltage standard has recently been maintained by using the Josephson effect in more than ten countries. The voltage standard had been maintained by the standard cell for a long time. The stability of the voltage standard has been improved by the introduction of the Josephson voltage standard. The Josephson voltage standard is based on the constancy and universality of the fundamental physical constant 2e/h. The adopted value of 2e/h in ETL is 483 594GHz/V. The accuracy of the Josephson voltage standard is 10-7 to 10-8 in the practical use. The further improvement of the accuracy would be expected. The commercial Josephson voltage standard system will be widely used in near future.
In this article, the above profile of the Josephson voltage standard is described.
