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Re: (ET) Triage - ideas from an unexpected result



VERDICT: SERIES WOUND MOTOR.

Here's what I learned:
- at least one series motor in the is crazy world can run wired as shunt (AND it MOVED a load that way!)
- a BIG series motor won't nec turn wired as series with too low an input voltage (it spun wired up as shunt with 12 or 24v, but DID NOT wired up as series with that same voltage)
- armature resistance measurements, especially with old and crudded commutators, can vary wildly
- sometimes series field winding terminals are labeled "F" and not "S."

THANKS everybody. Happy to have that one sussed.

-Max

On Thu, Feb 17, 2011 at 2:41 PM, Max Hall <mhall maxmatic com> wrote:
Good thought, David! That would explain near-zero resistance field windings, and if the brushes are old and the commutator is scratchy (both true) then maybe I wouId get artificially high armature resistance readings. I like it, and I'll find out.

BTW, if it is a series motor, then I will be surprised on at least one count: I made the motor turn by wiring it up as if it were series and it didn't work, and I wired it up as shunt and it did, but at low-ish voltage (12v or 24v, I can't remember) back when it arrived at my house.

Those of you with more experience might already know how this will turn out... (if, for instance, it is simply impossible for a series motor to turn if wired up with field and armature in parallel) but I don't!

I'll report back after I do a little more homework,

Thanks for all of your thoughts, yous guys,

-M


On Thu, Feb 17, 2011 at 1:54 PM, David Roden <etpost drmm net> wrote:
Are you sure it's a shunt motor?  It sounds more like a series motor.


David Roden - Akron, Ohio, USA

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