A high-precision ohmmeter used to measure resistances in the milliohm or microohm range. It typically uses a four-wire Kelvin connection to inject a known test current and measure the resulting voltage drop, eliminating the resistance of the test leads from the final reading. Engineers use it to verify the integrity of busbar joints, switch contacts, and motor windings.
Heard on the job
Grab the milliohmmeter and check the contact resistance on that vacuum breaker before we put it back in service.
Insider tip
A standard multimeter is useless for these measurements because its own lead resistance is often higher than the joint being tested.
Also heard as
- microohmmeter