– the intergovernmental organization through which Member States act together
     on matters related to measurement science and measurement standards.
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Electrical system

The current source

    A current of about 1 mA is injected into the moving coil by a bipolar current source built at the BIPM. Over 1 minute, the relative standard deviation of the current is about 4 × 10-7, with an integration time of 80 ms. The relative current drift is about 2 × 10-9 per minute.

Voltage reference

    The correct operation of the core of the watt balance voltage reference, consisting of a dedicated programmable NIST SNS Josephson array, which was donated by the NIST to the BIPM, has been verified. This comprises a total of 33 705 Josephson junctions divided into 13 independent cells. In operation the voltage across the coil leads is tracked by the voltage produced by the array; the voltage difference is then within the selected range of an analogue detector. A bias current source which allows independent control of every cell in the array is under development.