Flexible system for precision and automatic comparison of AC measuring devices

A multipurpose modular system for comparison of AC-DC converters and other AC measuring devices was built at IEN. It allows the performance of measurements for a large set of devices in a wide range of voltages and currents. In particular, for currents up to 2 A, a special transconductance amplifier that supplies the current keeping the conjunction point of the two devices under comparison virtually at ground potential is integrated. The comparison system takes full advantage of automatic procedures, but with accuracy typical of the best manual systems. For example, groups of single-junction thermal converter comparisons show a typical spread (1σ) of less than 1×10^-7