Volume 5, Issue 3 (May 1977)
Precision Secondary Resistors
Data on the stability of resistance of four types of secondary standards containing either Manganin® (a copper-manganese-nickel alloy) or nickel-chromium-aluminum-copper resistance wire have been measured for 19 secondary standards. The standards range from 0.01 to 1000 ohms and have been tested annually for about 7 to 14 years, although one standard has been in use and tested for 33 years. The change in resistance in parts per million is documented, and causes for the change are suggested. For the most part, the stability of resistance of the precision secondary standards is much less than the manufactured tolerance of ± 30 ppm/year.