Different winding configurations, core length, and different sizes of motors or generators mean very different values of winding Inductance. Take a DC Motor as an example. The series windings consist of a larger diameter wire with fewer loops around each pole. The shunt windings comprise a much smaller diameter wire with many turns around each pole.

In order to optimize the inductance measurement of these two fields, your MCE test equipment applies different test frequencies. For the many turns, but smaller wire of the shunt field, use a lower Frequency (300 Hz) test signal. For the larger, but fewer turns of the series field, apply a higher frequency (1,200 Hz) test signal.

Of course, not every motor manufacturer follows the same design. Change the frequency selected by your test equipment if you find yourself outside the inductance measurement range of the default frequency.

In this situation, remember to change the test signal frequency of your MCE as necessary. Modify the inductance range of the MCE test equipment.

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