On 15 Sep 2012 at 15:27, The CZ Unit wrote:
I think this is the difference between the E15 and E20; with the
compensation field the motor will slow down under heavy load and
provide more power.
Back in 2006, Walt Konstanty from GE posted an excellent description of the
operation of the compound motor used in some ETs. To wit :
"Compound winding means there's a 'light series' winding on top of the main
shunt field winding which adds flux proportional to armature amps to help
the main field produce torque as load goes up. Unless you change its
polarity in reverse, it will do the opposite with load - decrease main
field
flux and motor speed increases. That's why no field weakening in reverse
and higher speed under load. The reason it's used is to compensate for
armature reaction (current in the armature makes flux which cancels field
flux and causes speed to rise inherently under load)."
David Roden - Akron, Ohio, USA
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