Reconfigurable Unit for Precise RMS Measurements

A system for the precise measurement of electrical quantities by means of the root-mean-square (RMS) value of ac voltages or currents is described. The system is based on a planar multijunction thermal converter (PMJTC) and low-cost electronic components. The miniboard circuitry can also be used in several experiments where flexibility is required. As a first application, the system can carry out ac voltage comparisons and ac or dc voltage measurements. The system is designed to operate with a single PMJTC sensor in the range where its sensibility is greater. This paper shows the possibility of employing the PMJTC sensors outside the laboratory environment. The performance of the unit has been characterized, and measurements of ac signal RMS values in the audio band (below 1.5 V) show stability better than 3 muV/V.