The WRT-10 series are high performance winding resistance testers designed for power transformers and large motor applications.
Winding resistance testing is an important part of a power transformer maintenance or a manufacturing quality assurance program. Transformers & large motors are subject to vibrations, overloading and environments with large temperature variations. Winding resistance measurements can assure that the connections are made correctly and that no opens or shorts are present
The WRT-10 injects a DC current through the win- dings & measures the voltage drop. The instrument calculates the resistance R= E / I. The challenge in winding resistance measurements is that the voltage across an inductor is defined by V= L (di/dt), where L is the inductance of the winding & (di/dt) is rate of change of current. Therefore small changes in the current, as may be caused by ripple or poor regulation, can make it impossible to measure the DC resistance.