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Re: (ET) Resistor Strap

John,
the length of the shunt wire does not affect the actual current, only the reporting of it on the meter. With 20 inches, it should be reporting correctly now. (The longer wire would have a higher voltage drop, which would show a higher reading on the power use meter / ammeter.) Shortening the shunt wire further will under-report your actual current usage, but not reduce the real current being used. In short, don't do it.
It may be the resistor is working as desired, if it is engaged. You want to spend the minimum time possible in the lower two speeds (engaging the resistors), and maximum time in the highest speed (no resistors engaged).
I did encounter a problem where one of the contactors was not working, and spent much time with the single resistor (speed 2) engaged when I had the selector in speed 3 (should have been no resistors). I replaced the contactor to resolve the problem.
The resistor strap is likely sized for continuous duty. I have never heard of anyone burning one up. Personally, I would recommend operating in the slower transmission speed and speed 3 (no resistors engaged) over the higher transmission speed and using the resistors extensively. 

Darryl McMahon

John Casey wrote:

Thanks for responding.  It is a three speed controller.  Not much
slow maneuvering.  While snowplowing in D1 the power use meter stays
at the upper end of the green.

When I first got this tractor in 2000, the power use meter ran in red
and sometimes pegged when tractor under load.  Don't remember
checking for a hot resistor strap but did see in the homeowners
manual that the shunt should be 20" long; mine was almost
21'"...reinstalled it at 20" with no more running in the red.

Is it wise to re-install the shunt at 19" to help with the current
problem?

Thanks, Jack ----- Original Message ----- From: RJ Kanary To: John
Casey ; elec-trak cosmos phy tufts edu Sent: Friday, December 09,
2005 6:36 PM Subject: Re: (ET) Resistor Strap


Ideally, it should not be hot at all . Reality however is different.
The only time the resistors are in the armature circuit is when the
first two or three speed positions are used ,{Depending on whether or
not your tractor has three, seven or eight motor speeds available.} Once the resistors are bypassed by the contactors, this is when the 
most efficient operation is achieved. If you are doing a lot of slow
maneuvering , this is when your electrons make more heat than torque.
 On the plus side, it DOES keep the snow off the hood. :)

----- Original Message ----- From: John Casey To:
elec-trak cosmos phy tufts edu Sent: Friday, December 09, 2005 5:06
PM Subject: (ET) Resistor Strap


All:

How hot should the resistor strap get?

I plow a neighbor's driveway and my own, about 200.'  Last week we
had a 3" snowstorm and I stayed in D1all the way. The perforated
metal over the resistor strap was hot to the touch but not hot enough
to make me remove my hand....of course, the strap would have been
hotter.  Battery clamps were tight and cool, traction motor luke
warm, contactors warm, diode/varistor block looks okay.  Today we got
10" of heavy snow and not to be stupid I stayed in L1 all day.  The
perforated metal cover was only warm and other avovementioned
checkpoints were normal.  After clearing snow from both storms there
was plenty of tractor range left.

The 9 page 'Owners Use and Care Manual" shows that snowplowing can be
done in range D2.  I would like to plow in D1.  Can anyone tell me
what the acceptable heat level is with this strap.

Thanks, Jack




--
Darryl McMahon                  http://www.econogics.com
It's your planet.  If you won't look after it, who will?