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Considerations when working with compound wound DC fields

Publication date: 
December 2014
Chuck Yung, EASA Senior Technical Support Specialist
Type of media: 

Occasionally a customer wants a spare DC machine, and you find a replacement that is almost – but not quite – identical. Often, either the original or the spare is compound wound. The customer then asks: “What do the series fields do?” and “Can we just isolate the series leads?” 

There are a couple of considerations, but the answer is that “it depends.” If the nameplate is factory marked “Stabilized shunt” or “Stab shunt,” that tells us that the series contribution to total field flux is relatively small. In many applications (e.g., extruder), the relatively small series is not essential to successful operation of the motor.

Topics covered in the article include:

  • Shunt and series field
  • Flux contribution
  • Higher percent compounding
  • Inductive kick
  • Shunt field failure
Field coils