microohmmeters

A microohmmeter is an electronic instrument used to measure very low electrical resistances, typically in the microohm range (10^-6 ohms). These resistances are too small to be accurately measured by standard multimeters. Microohmmeters employ a four-wire measurement technique, also known as Kelvin sensing, to eliminate errors caused by the resistance of the test leads and contact points. In this method, separate pairs of leads are used for current injection and voltage measurement. Current is passed through two outer leads, and the voltage drop across the resistance is measured by two inner leads. This isolates the resistance being measured from the influence of the test lead resistances.

Microohmmeters are essential tools in various industries. They are used for verifying the integrity of low-resistance connections, such as those found in electrical grounding systems, switchgear, circuit breakers, and power busbars. They are also employed in the manufacturing and testing of components like motor windings, transformer windings, and cables. Accurate measurement of these low resistances is crucial for ensuring the safety, reliability, and efficiency of electrical systems. Modern microohmmeters often incorporate digital displays, data logging capabilities, and various safety features.