STATOR WINDING RESISTANCE TEST

 

STATOR WINDING RESISTANCE

 

Winding Resistance Test

The value of a test current should be selected according to the nominal winding current. Information about nominal winding current could be found on the nameplate of the test object. The test current should not exceed 10% of the nominal winding current. Because of cables heating, higher values of test current will significantly increase the winding resistance.

The winding resistance of three-phase AC motors is measured between their terminals (all three combinations).

Figure 2 – Measuring the stator winding resistance of an AC motor

Figure 3 – Connection for measuring the stator winding resistance of induction motor

Winding resistance of slip-ring rotor is measured directly on the slip rings (non-linear transition resistance of brushes is not included in the measured winding resistance).

Figure 4 – Measuring the winding resistance of the slip-ring rotor

Figure 5 – Results menu of RMO-M

Discharging Motor After Winding Resistance Test

Be aware of a possibility the energy still remains in a magnetic circuit. After the measurement has been completed the RMO-M device will start the current discharging process automatically. During the current discharging the ”DISCHARGING” message is shown on the device display.

Figure 6 – The discharging message

The leads should never be removed during the testing process. The operator should always wait for a discharging signal and a buzzer sound signal to end. That is an indication the tested motor has been properly discharged.

The current injection and energy discharging process are fully automatically regulated. The safe discharging circuit, equipped with an indicator, rapidly dissipates the stored magnetic energy after the test completion.

CAUTION: The test leads should not be disconnected before the “Discharging” message disappears from the display and the discharging LED is off.

After all the tests have been completed, the test leads are disconnected in the following order:

the test leads are removed from the test object

the test leads are removed from the instrument.

The mains voltage supply cable is removed first from the supply source, and then from the instrument. Finally, the ground (PE) cable is removed from the instrument.

 

STATOR WINDING RESISTANCE

Temp: 38°C

PHASE	U	V	W
Resistance in mΩ	5.304	5.312	5.295