A new wattmeter for traceable power measurements at audio frequencies

This paper describes the development of a wattmeter designed for traceable power measurements to 30 kHz and above. A description is given of a technique, which uses the three rms values of voltage, current and sum of voltage and current-to-measure power. The resulting system is based around an analog signal processor, which provides signal ranging and isolation. The design of the signal processor includes several unique aspects. Traceability is achieved by characterization of each stage of the system; this, together with the overall measurement uncertainties, is reported. The results of comparisons with other standards are given