The Winding Ohmmeter RMO10TW is a portable and lightweight instrument (7,5 kg / 16.5 lbs) designed for the winding resistance measurement of inductive test objects and for on-load tap changer verification. The RMO10TW instrument generates a true DC ripple-free current with automatically regulated measurement and discharging circuit. The injection of current and discharge of energy from the test object are both automatically regulated. The three independent channels enable testing of three windings in series. This instrument enables measurements of a winding resistance in every tap position of an on-load tap changer without discharging between the tests. Problems with switching of the OLTC, such as interruption, can be detected with these measurements.