Glad to help out here Wendel!
As to the follow-up question:
The bottom line for my purposes is if any speed tap demonstrates a short to ground then all speeds are condemned to the same fate.
A:
_ If the Motor is energized, and the Tap which has the Ground Fault
_"IS NOT"_:
- The Selected Speed Tap,
or
- The "High Speed" Tap;
Then the Autotransformer Windings will have circulating Currents flowing from the Motor Lead, to "Ground" - via an EGC.
This will not have an affect on the Motor's performance - UNLESS - the Autotransformer becomes excessively hot - at which point will cause heat issues throughout the Motor.
B:
_ If the Ground Fault occurs on the Winding - AHEAD OF - the Speed Selection Tap point, this would dramatically affect the Motor's performance, as the Motor Windings would see an extremely reduced Voltage.
C:
_ If the Ground Fault occurs on "The Selected Speed Tap", then this would be a Short Circuit, which "Should" trip the OCPD.
D:
_ If the Ground Fault occurs on the "High Speed Tap", and the Speed Selection is made to one of the Tap points "Ahead Of" the High Speed Tap, then the Motor would see very low Voltage (if any).
E:
_ If the Ground Fault occurs on the "High Speed Tap", and the Speed Selection is made to the "High Speed" point, this would be a Short Circuit Ground Fault.
Hope this makes sense!
Scott35
