From: "Justin Farrelly"
Subject: Re: series wound motor
Date: Sat, 19 Oct 2002 13:21:28 +0000 (UTC)
Organization: BT Openworld
References: <email@example.com> <3DB15191.68DD9284@webaccess.net>
NNTP-Posting-Date: Sat, 19 Oct 2002 13:21:28 +0000 (UTC)
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Agree with Chuck, series wound DC systems are typically only used for very
high torque at start applications such as starter motors. His figures seem
pretty spot on, and of course the impedance goes up as the speed of rotation
goes up, and torque drops off as a consequence. If you want to find more
general information on DC motors for industrial use as a whole, and
construction techniques, calculation conciderations, etc, one of the best
places is old marine electrical text books from the 1930's. Everything on
old ships was DC. When I started work, we had a massive DC switchboard and
lots of DC motors for almost all our engine room services. What a job,
stripping, cleaning and refurbishing!!
Hope this helps,
"Chuck Simmons" wrote in message
> Martin Perry wrote:
> > I am trying to find the expected inductance and resistance for both
> > and field windings of a series wound, 12V, 5HP DC motor. I don't have
> > measuring equipment so could anybody give me an estimate please.
> > Regards, Martin
> This is about like a starter for a 5 or 6 liter gasoline engine. The
> power is about 4000 watts including losses so the current is above 340
> amperes. The total motor resistance is maybe 0.035 ohms. You could
> divide that evenly between the armature, the stator and the brushes and
> nobody will ever prove you wrong. Inductance is anybody's guess since it
> will be quite variable. At full load, it will be be pretty low. With
> zero current, it will be much higher. A guess might be 10 milliHenrys.
> That's pure SWAG, however.
> ... The times have been,
> That, when the brains were out,
> the man would die. ... Macbeth
> Chuck Simmons firstname.lastname@example.org