Analysis of the voltage coefficient of high value standard resistors

Standard resistors in the field 100 MΩ–1 TΩ, normally available in National and secondary laboratories, were measured and characterized with respect temperature and applied voltage [F. Galliana, G. Boella, High value resistors: study of their behaviour versus applied voltage”, in: Proc. of the 16th IMEKO World Congress, Wien, Austria, September 25–28, 2000; F. Galliana, E. Gasparotto, R. Cerri, Evaluation of the temperature and voltage coefficients of high value resistors, IEN Technical Report no. 565, February, 1999]. The measurements were carried out with a system based on the use of a digital multimeter (DMM) [F. Galliana, G. Boella, The electrical dc resistance scale from 100 kΩ–1 TΩ, IEEE Trans. Instrum. Meas. 49 (5) (2000) 959–963; F. Galliana, G. Boella, P.P. Capra, Calibration of standard resistors in the field 10 MΩ–1 TΩ by means of a digital multimeter, in: Proc. of IMEKO TC-4, vol. I, Naples, September 1998. pp. 191–195; G. Boella, F. Galliana, Comparison of different methods for the calibration of standard resistors in the range 10 MΩ–1 GΩ, in: Proc. of 8th Int. Metrology Conf. Metrologie 97, Besancon, France, October 20–24, 1997. pp. 457–461].Most standard resistors showed a behaviour versus applied voltage that can be represented by a function having a linear plus a quadratic component. Some of them were also measured at different conditions of relative humidity: the influence of this environmental parameter on the voltage behaviour of the standards has been analyzed.An evaluation of the influence of the variation of the leakage resistances was also be done.