Accurate Low-Resistance Measurements Start with Identifying Sources of Error
Low-resistance measurements are subject to many of the same sources of error as low-voltage measurements, including offset voltages due to thermoelectric EMFs, offsets generated by rectification of radio frequency interference (RFI), and offsets in the chosen instrument's voltmeter input circuit. Noise sources that can interfere with low-resistance measurement accuracy include Johnson noise, magnetic fields, and ground loops. Excessive common-mode current can also affect low-resistance measurement accuracy. Low-resistance measurements are subject to error sources such as lead resistance, non-ohmic contacts, and device heating. This white paper addresses methods to eliminate or minimize these error sources, as well as other measurement considerations, including dry circuit testing and testing inductive devices.