European calibration service for high-frequency AC power measurements

‘The calibration of AC electrical power has always been a challenge’, comments Terry Marrinan, Yokogawa’s European Sales & Marketing Director: ‘The calibration of AC power is different from calibrating just voltage and current, and only a few calibration laboratories worldwide are actually able to carry out AC power calibration.’

Commonly, the calibration frequency range for AC power is limited between 50 and 440 Hz. Today, however power meters are used for measurements on switch-mode power supplies, high-frequency electronic lighting ballasts, soft starters in motor control systems, and frequency converters in traction applications. The phase shift has now become one of the most critical specifications for the high bandwidth power meter’s uncertainty.

The introduction of the Yokogawa WT3000 wide bandwidth power analyser - the successor to the ‘legendary’ 2885 industry standard watt converter – has revealed the big gap in available national standards between the two calibration frequencies of 50 Hz and 1 MHz.

The team leader of the NMi’s DC and LF electricity department, Dr. Ir. Gert Rietveld, recognised that more effort needed to be taken by European national metrology institutes. Under his supervision, the accreditation of AC power of NMi, the Dutch National Metrology Institute, increased in frequency up to 100 kHz.

‘The National Metrology Institutes need to keep ahead of the increasing accuracy of commercially available power meters’ comments Dr. Rieyveld: “On many occasions, the difference between our generated reference values and those measured by the Yokogawa WT3000 reached the limits of the NMi systems’ uncertainties.”

The Calibration Laboratory of Yokogawa Europe B.V. was established in 1982, initially to calibrate the working standards for parameters such as length, pressure, pH, weight, conductivity, voltage and current used in the manufacture of liquid analysers.