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Just had a thought about catching frame grounds early.
I've noticed that in industrial situations where 3-phase delta-connected
power (three hot wires totally unrelated to ground, no neutral) is used,
electricians sometimes connect a light bulb from each of the hot wires to
ground. Since the three hot wires don't have a relationship to ground, the
bulbs all glow equally running in sorta-series. If there's a ground fault,
i.e., if one of the hot wires gets connected to ground by accident, the bulb for
that wire goes out.
We could do the same thing, I think. Just connect two small
(something that would take a least a quarter of an amp) 36-48 volt bulbs, one
from the plus end of the pack to the frame, and one from the negative end of the
pack to the frame. Properly fused of course. Maybe with one fed from
the load side of the key switch so that they were only on when the tractor
was.
>>> Dave & Debbie Barden <daveb seanet com> 1/26/2004 8:38:50 AM >>> because of some red-orange paint I thought for a while it might be a wheelhorse but the the GE symbol is there on the front grill. there's no hole up front where the PTO plug may've been. The tractor has been painted JD green including the name plate on top of the dash unfortunately and the data plate under the hood isn't there. Unless I can get some info off the painted plate atop the dash I'm afraid all I'll have to go on is physical description. the tractor's on the island and it'll be friday before I can get there again. thanks for the warning/confirmation that I've a dangerous situation that must be fixed immediately. I'm taking that to heart... dave seattle > As my Dad, the electrician who had 30 years of experience with DC > operated overhead cranes would say, "Son, you've got something that's 'gone > to ground'." > {Actually, in most cases two items have to fail to make obvious > symptoms.} > > The most common culprits in the Elec-Trak® are....... > 1.) Armature resistor contactor bushings. > 2.) Armature terminal bushings on the traction motor, or brush rigging. > 3.) Lift motor. > This situation is VERY dangerous, and must be investigated and repaired > immediately. > I have never seen a tractor with the PTO outlet where you have described > it. Give us the numbers from the data plate, under the hood, and I think we > can puzzle it out. > > ----- Original Message ----- > From: "Dave & Debbie Barden" <daveb seanet com> > To: <rjkanary nauticom net>; <tcoate coate org>; > <elec-trak cosmos phy tufts edu> > Sent: Sunday, January 25, 2004 2:54 PM > Subject: pack not isolated from frame?? > > > > > > I was working on my modified E15 (?) today, and while loosening a > connection on > > one the cable connections I grounded to the body with the wrench and got > an > > ugly juicy spark. That doubly surprised me because I am always careful > around > > battery terminals and potential grounds but also because I thought that if > the > > pack was not grounded to the frame you wouldn't/shouldn't get current > flow?? > > > > So what gives here am I under a mis-impression and showing my ignorance or > do I > > have a ground somewhere that I shouldn't have?? > > > > Also since this tractor has been modified by the previous owner I don't > really > > know what model it is. My E12S has the PTO plug up front on the left. > This > > one has the PTO plug down by my right foot. Would this be an E15 or E20 > or??? > > > > thanks much, > > dave > > Seattle > > E12S > > E?? modified > > > > > > > > > > > > > > _______________________________________________ Elec-trak mailing list Elec-trak cosmos phy tufts edu https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak |