The METAS watt balance: a summary of progress

The Swiss Federal Office of Metrology and Accreditation (METAS) has been continuing its drive towards a 100 g watt balance apparatus with a relative standard uncertainty of 1/spl times/10/sup -8/. The objective of this kind of measurement is, presently, to measure the Planck constant and improve the consistency of the SI. In the future it is hoped that the watt balance approach will help in a redefinition of the kilogram. Currently the experiment is producing preliminary measurements reproducible at the 1 ppm level. Our progress, measurements, and plans for the future are presented.