A primary standard of voltage maintained in solid-state references

In September 1984, the 54 saturated standard cells which had been used to maintain the Fluke corporate volt were removed from service and placed in storage. Since that time, Fluke´s corporate volt has been maintained in 4 solid-state, 10-V references. Discarding the cells has much reduced the time and cost of maintaining the standard, has significantly decreased its uncertainty, and has much improved the confidence that stated uncertainties are actually attained. An uncertainty of +/− 0.08 ppm was assigned to the difference between 10 V at Fluke and 10 V as maintained by NBS and an uncertainty of ±0.40 ppm to the absolute value of the Fluke 10 V. This paper describes the hardware and the statistics utilized in establishing the solid state primary standard of voltage and reports the results attained to date.