I've always been one to check for poor connections/high resistance with
the "Human Contact Thermometer" called a finger, but this too is a good
example why I just bought a Craftsman Infrared Thermometer off eBay for
about $30. Not to mention the slightly burned finger tips, but also the
cuts and bruises when you too quickly withdraw your hand out from under
there and hit something on the way out.
And I'd be willing to say that there are some of you out there saying,
"Yeah, been there, done that".
Mike in KY
----- Original Message ----- From: "Christopher Zach" <czach computer org>
To: <ev listproc sjsu edu>; "Elec-trak list" <elec-trak cosmos phy tufts
edu>
Sent: Monday, April 04, 2005 9:51 PM
Subject: (ET) Nailed
Well, it happened sooner than later. I got nailed by my Elec-Trak.
Shocked on the left hand, and quite painful.
Why you might ask? An Elec-trak is only 36 volts. And we all know that 36
volts is safe...
Well, I was checking the temp of one of the shunts in the tractor. It's
an exposed copper strip that was getting very warm under full load. So I
put my hand in the unit and felt the temp with my finger while bringing
the tractor up to speed. Then I cut the power to the motor.
*WHAM*
Felt like my hand was bitten. I pulled back; damn it hurt.
What appears to have happened was that when I stopped the motor my hand
was touching the shunt strip and one of the contactors. My guess is the
transition of motor from on to off created a big EMF voltage spike either
in the field or the armature, right thru CZ's hand.
Moral of the story? You can be bitten by 36 volts. I take precautions on
the Prizm's pack (never pull pack out without first subdividing it into
60 volt segments *BEFORE* it comes out, all paths to the pack isolated,
always use gloves, never reaching over the pack, etc) however this serves
that one can even get bitten on something as innocent as an E20.
Chris
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