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Temperature and Pressure Coefficients of Thomas 1 Ohm Resistors



George R. Jones Jr., Randolph Elmquist


In preparing to move the precision 1 ohm measurement service to the new Advanced Measurement Laboratory (AML) in the spring of 2004, staff at the National Institute of Standards and Technology (NIST) first assembled a second precision 1 ohm measurement system in the AML. This allowed for the calibration service to continue uninterrupted during the transition. Both systems are fully automated and all calibrations include the measurement of laboratory ?influence factors? including the bath temperature and atmospheric pressure. Over the past year additional components have been added to these two systems which enable NIST to characterize the behavior of precision 1 ohm 'nresistors over a wide range of temperatures and pressures. These modifications include both an auxiliary thermal oil bath and a pressure chamber, each having capacity for up to three precision 1 ohm resistors. Approximately twenty resistors have gone through a battery of thermal and pressure tests at temperatures from 20 ?C to 26 ?C and at pressures from 80 kPa to 110 kPa. Tests have shown that some Thomas-type resistors experience non-reversible shifts in their values due to pressure changes.
Proceedings Title
NCSLI Workshop & Symposium
Conference Dates
August 6-10, 2006
Conference Location
Nashville, TN, USA
Conference Title
NCSL International Workshop and Symposium


coefficients, precision, pressure, resistors, temperature


Jones Jr., G. and Elmquist, R. (2006), Temperature and Pressure Coefficients of Thomas 1 Ohm Resistors, NCSLI Workshop & Symposium, Nashville, TN, USA, [online], (Accessed April 16, 2024)
Created July 31, 2006, Updated October 12, 2021