Characterisation of thermal converters with a Josephson standard

To realise the units for alternating voltage, alternating current and electrical power with the lowest measurement uncertainty at RISE, thermal converters are used. With a thermal converter, an unknown alternating voltage (ac) can be compared to a known direct voltage (dc) that is traceable to natural constants via the Josephson effect. Each thermal converter has an error (ac-dc difference) that must be characterized as part of the realisation. In this project, new characterization methods will be developed with a programmable Josephson standard, which can generate precisely defined (quantised) direct voltages and alternating voltage signals with calculable RMS value.

After the project, RISE will be one of few NMIs (National Metrology Institutes) in the world with its own realisation of the alternating electical units, which makes us independent of external actors and increases the security of the traceability chain. The new methods will also be used at RISE to improve measurement uncertainty during calibration in the low-frequency range (<1 kHz), especially at 3–10 Hz, since measuring instruments with significantly better performance in that range than before have come onto the market.