It eliminates the lead resistance and is typically more accurate.Īll winding resistance measurements done with Electrom Instruments motor testers are done with a four lead system. This type of resistance measurement will include the tester’s leads in the winding resistance test’s measurement. Resistance can be measured with two leads connected to a DUT. The difference in percent to the target resistance value is then calculated.Ī temperature correction factor can automatically be applied to correct the measurement to a standard temperature so results can be more accurately tracked over time with the winding analyzer. Using Ohm’s law the resistance is calculated in µΩ (micro Ohms) or mΩ (milli Ohms) by the winding analyzer.įor a 3-phase motor, 3 resistance measurements are normally done between the phases, and the balance or imbalance between the 3 measurements is calculated and displayed along with the measurement values.įor single coils and sometimes for motors, the resistances measured may be compared to a resistance value instead of having a balance calculated. Winding resistance tests are a measurement of the applied DC voltage and current to the device under test -DUT. Some of these are the wire gauge issues, resistive connections, and blown or disconnected magnet wires in hand.
Winding resistance is an important measurement because other tests and measurements will not find some of the problems a resistance measurement will find. The winding resistance test is used to find open windings, shorts to ground, wrong turn count, wrong wire gauge, resistive connections, round wires in hand that are not connected in a coil, some connection mistakes, the resistance balance between phases, and in some cases shorted turns.