Quantitative current data allows localization of ground. To perform these tests obtain a test signal from a power source and insert an ammeter between source and probe. Provide a return lead to the source from the motor frame.

In Figure 6-25, connecting the probe to point “A,” which is closest to the grounded coil will provide a higher current flow then when connected to Points “B” or “C.”

Figure 6-25 - Localizing Ground with Ammeter

It is harder to localize grounds in delta configured windings because current differences aren’t as great due to multiple flow paths.