(ET) Motor control

["Rhett T. George" <rtg ee duke edu>]

 - Greetings -

I applaud Allan's interest in building an FET-based controller for his
E-20.  Hopefully he will tell us of his many successes and how to avoid
any failures that might beset him.  

Steve gave some enlightening comments regarding the GE motor wiring.  None
of my schematics had indicated the possibility of switching the armature
circuit to obtain reverse.  Steve did mention stabilization windings which
are omitted from my schematics as well.  He has described those windings
well.  This connection is known as the differentially-compound motor.
Those windings must be very few in number lest the increase of armature
current effectively reduce the field to zero.  

In the instance where the field from the added series winding reinforces
the shunt winding field, the motor slows down a bit more than for the 
straight shunt motor, but more torque is developed.  This connection is
known as the cumulatively-compound motor.

Hope this helps.

                                        Rhett George