DC resistance tester is often referred to as direct resistance meter or micro-ohmmeter in the power industry



If the winding deformation tester we discussed earlier is like a "bone CT" for transformers, then the DC resistance tester is a precise "vascular patency check" for the transformer's windings and conductive circuits. Its core task is to measure extremely low DC resistance with high precision, thereby identifying hidden connection issues in the equipment's internal conductive circuits.

⚙️ Core Uses and Importance

DC resistance measurement is an essential test item for inductive loads such as transformers, instrument transformers, and large motors during factory acceptance, commissioning, major overhauls, and after changing tap changers.

Core Functions: By measuring the DC resistance of windings, it can accurately check whether the welding or connection quality of leads is good, whether there are inter-turn short circuits or open circuits inside the windings, whether the tap changer contacts are properly engaged, and whether there are broken strands in multi-strand parallel windings, as well as other manufacturing defects or operational hazards.

Wide Applications: In addition to transformers, it is also widely used to measure the contact resistance of high-voltage switches (circuit breakers), the DC resistance of cable conductors, and the loop resistance of busbar connection points. It is a mandatory test item in preventive tests for power systems.