On 21 Feb 2015 at 11:56, Dan Baker via EV wrote: > I used to check it regularly with my hand for > temps, barely would get hot. Now the "H" rated insulation is melting!
I'm not a motor expert, but I think the most usual causes for overheating where there was none before would be 1. Overloading of the motor, perhaps because of something binding (brakes? wheel bearing?) or high friction somewhere; or 2. Very low motor field current. This second shouldn't happen with a series motor; field current is supposed to always equal armature current, but you say field weakening is installed somehow on this cart. Something seems odd about that though. I have the "turbo" field weakening in the Alltrax in my GE Elec-trak tractor, which has a compound (shunt strongly dominant) motor with the controller managing the field. I've never used a series motor Alltrax. How does it manage field weakening? Does it pull in a contactor for a resistor across the field? Assuming that FW is actually implemented here, I would disable it completely. Remove the shunt's connection to the field, on the chance that its contactor has welded shut. Also make sure you can push the cart easily by hand on a dry surface. Rolling resistance and friction should be low enough that it rolls when you push it with one finger. I'd also put an analog ammeter on there to keep an eye on motor current. David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
