The electrical DC resistance scale from 100 k/spl Omega/ to 1 T/spl Omega/ at IEN

At IEN, the scale of resistance in the field 100 k/spl Omega/ to 1 T/spl Omega/ has been revised through the characterization of a series of new standard resistors. The preliminary study, realization and characterization of four measurement methods are also described in this paper. The complete description of a new automatic method for the calibration of high-value standard resistors, particularly in the range 10 M/spl Omega/-1 T/spl Omega/, and their measurement at different voltage levels are also reported. It makes use of a programmable high-stability dc voltage calibrator which supplies a voltage V/sub out/ to the series of an unknown resistor R/sub x/, and of a standard resistor R/sub s/. A high-precision programmable multimeter (DMM) is used to measure V/sub out/ and the voltage Vs across the standard resistor, from which the value of the current I is determined. The value of R/sub x/ is given by R/sub x/=(V/sub out/-V/sub s/)/I. The best measurement capabilities of IEN using these four measurement methods span from 0.7/spl times/10/sup -6/ for the calibration of the 100 k/spl Omega/ standard resistor at the measurement voltage of 10 V, to 7.1/spl times/10/sup -4/ for the calibration of 1 T/spl Omega/ standard resistor at the measurement voltage of 500 V.