Re: (ET) ge pulling

["Markus" <ev lorch net>]

Hi Guys,

I was referring to the internal heat sensor/switch that is built into 
the motor. Wondering if that would only protect the field windings or
also open in time before the armature gets too hot. I could immagine that
for longer term high usage this is adequate protection as the heat has 
time 
to propage thoughout the motor. For very brief very high power demands 
(like
when doing a pull) I am not so sure that it would tripp early enough.

I have taken the klixon units apart in the past and can confirm what 
you guys say. It is a simple thermal breaker. To a small degree it does 
take
motor temperature into account as it is being mounted on the motor but that
is negligible, especially for short term very high load.

Markus

> -----Original Message-----
> From: elec-trak-bounces cosmos phy tufts edu 
> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of Jim Coate
> Sent: Donnerstag, 1. Juni 2006 15:29
> To: Elec-Trak
> Subject: Re: (ET) ge pulling
> 
> 
> The Klixon is most definitely an external thermal circuit breaker; it 
> has no way to measure the motor's internal temperature. It 
> should take 
> ~10 seconds to trip at double the current rating, and ~1 second at 
> 5x-10x the rated current. As it is thermal based, it will also be 
> slightly influenced by ambient temperatures (ie trip sooner 
> on a hot day).
> 
> In general I would never recommend bypassing protective 
> devices, but... 
> if I was doing a short pull and knew the motor would then have a long 
> cool-down time....
> 
> 
> Tim Humphrey wrote:
> > I know its not right to reply to yourself but...
> > 
> > I just read through some of the digest regarding the Klixon.
> > 
> > It seems that yes it is just a circuit breaker. It also 
> seems to be rated at around 80-100amps depending on your model
> > of ET.
> > 
> > For the purposes of "pulling" I would definately recommend 
> bypassing it and also not worry too much about burning yup
> > your motor.
> > 
> > Why?  Because on my sawmill, I have the drive motor (an 
> E-15 drive motor) wired directly with no protection. I will
> > occasionally cut a log 12"-14" diameter. During this cut I 
> am drawing a continuous 125-150 amps for a minute or two,
> > when finished the motor is warm to the touch. It usually 
> has 3-5 minutes to cool while I reposition things for the
> > next cut.
> > 
> > A full minute for a tractor pull would seem like an eternity.
> > 
> > I suspect that a tractor pull would have less of a duty 
> cycle and thus be less danger to the motor than my sawmill.
> > 
> > 
> > 
> 
> 
> -- 
> Jim Coate
> 1970's Elec-Trak's
> 1997 Solectria Force
> 1998 Chevy S-10 NiMH BEV
> 1997 Chevy S-10 NGV Bi-Fuel
> http://www.eeevee.com
> 
> 
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