Re: (ET) E15 motor is not a compound.

["David Roden" <etpost drmm net>]

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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