CRM 100B directly measures micro-ohm values at 100 Amps DC under live switchyard conditions. CRM 100B is specially designed to reliably measure the contact resistance of circuit breakers, isolators, busbar joints, welded joints, etc., under the hostile electrostatic noise found in live EHV switchyards up to 765 kV. An inbuilt rechargeable battery tremendously enhances utility as AC supply connectivity is not required. CRM 100B operates on a rechargeable battery as well as Mains supply. It has a built-in constant current source, a precision instrumentation amplifier, a digital readout, and control logic. A pulse of 100A DC is passed through the test object and voltage drop is sensed using the classical Kelvin?s 4-wire method to measure contact resistance.