<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body text="#000000" bgcolor="#FFFFFF"> My view from the bleachers. My deceased Dad was an industrial electrician for the then American Bridge Division of US Steel. He spent his last years of life with us. During that time, I acquired my very first Elec-Trak, an E-10. An I-5 and an E-20 soon followed. We had some good Dad & Sprout time with them. He quickly pointed out the similarities between the ET circuitry and the large DC operated overhead cranes used at the plant. He also pointed out that there was a primitive ground fault system using incandescent lamps to indicate that the crane and / or its supporting structure was HOT. All further use was halted until the issue was found and rectified. BAD things would happen if those warnings were ignored. Your mileage may vary. :) RJ <div class="moz-cite-prefix">On 12/2/2019 5:10 PM, Chris Zach wrote: </div> <blockquote type="cite" cite="mid:68f87ed2-8ede-9c48-2b63-fabf62583536@alembic.crystel.com">Ok, so I figured the motor was not going to fix itself and took it apart today. Removed the huge front pulley with my 3 fingered pulley puller, then pressed out the armature and set it next to the E15 armature. Note: It's a bigger armature, no doubt. I then unscrewed the field screws on the motor (hint: Find the *exact* size screwdriver, clean the slots of all crud that might keep the screwdriver from fully engaging, put penetrating oil in, and use a wrench on it while putting pressure down with your shoulder. These heads could strip) and started thinking about how to get the field wires out of the plastic housing (so I could thread them into the motor and pull the windings out) when I figured I should test the motor again with my sparker. No spark at all, no ground fault. Hm. Put the screws in on one field side: No ground fault. Did the other, ground fault. So it looks like the fault is between one of the field halves and the motor body. If the screws were not ferrous that could fix the fault but I don't know if nylon screws are made that big and if they would hold under the motor's heat range. Debating if it's worth it to pull out the field, I could wind up breaking more of the insulation and making it worse. I know that the short is to the metal field support and not to the motor body because it will spark on the inside of the motor on the side that's shorted. I might be stuck here running with a ground faulted motor, or I could bypass the whole compensating field and just run with the series one. Which would be a better option? _______________________________________________ Elec-trak mailing list <a class="moz-txt-link-abbreviated" href="mailto:Elec-trak@cosmos.phy.tufts.edu">Elec-trak@cosmos.phy.tufts.edu</a> <a class="moz-txt-link-freetext" href="https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak">https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak</a> </blockquote> </body> </html>