A new automatic reference and switching unit for calibration of high valueresistors in the range 100 k Omega to 10 T Omega

We describe a Reference and Switching Unit (RSU), that, with a digital mult imeter (DMM) and a de voltage calibrator, constitutes a system for calibrat ion of standard resistors in the range 100 k Omega -10 T Omega at measureme nt voltages up to 1000 V. This system represents an implementation of a DMM -based system already developed at IEN. We report the characteristics of th e DMM-based system, the metrological and electronic features of the RSU, th e uncertainty levels that can be achieved with the DMM-based and whit the R SU-based systems. Finally, we show the: obtained results in order to check the compatibility of the two systems in the calibration of standard resisto rs in the range 1 G Omega -1 T Omega. The 2 sigma best measurement capabili ties of the RSU-based system span from 6.3 x 10(-6) for the calibration of a 100 k Omega standard resistor at 10 V, to 1.2 x 10(-3) for tile calibrati on of 10 T Omega standard resistor at 1000 V. (C) 2001 Elsevier Science Ltd . All rights reserved.