Hi Mike, I am not familiar with that brand of contactor, but if it is DC rated at 200A and comes with jumper/bus bars, they should be sufficient. The current density is a bit high IMO but not out of sight. If they were totally enclosed and run for many hours continuously at 200A, I might be concerned. You can help draw heat by using large cables and lugs.
I guess you might be able to reconfigure bus bars/jumpers such that forward would be with neither coil energized and reverse with both coils energized. I've never seen it done and it might be hairy. Most of these DC reversing contactors go into fork lifts which have a 50/50 forward/reverse duty, so one coil on makes sense. Also, without either coil on, it is automatically in neutral, so to speak. And beware of reduced holding current if the contactors are not made for it. Bumps in the road may cause the contacts to separate and arc. Jeff M ________________________________ From: Michael A. Radtke <[email protected]> To: [email protected] Sent: Tuesday, April 9, 2013 2:50 PM Subject: [EVDL] Reversing Contactors Yet Again Hello, I apologize if I missed the answer to my questions in the archives. I have a Jet ElectraVan that I am replacing the old GE EV-1 SCR controller with an Open Revolt controller. I've used a home made reversing switch for years, but it's slow and showing some wear. I picked up a Contact Industries CT200C-12B1 200 amp reversing switch to replace my home made unit. Now I have some questions: 1) Is 200 amps enough? The car is 102 volts with a 20 HP motor. The motor current should average well under 200 amps, but I am a little concerned about the size of the bus bars on the contactor. They measure 1/2" X 5/32" and the supplied jumpers are 1/2" X 1/8" 2) This reversing contactor is built like every other reversing contactor that I have seen in that it has two contactors in tandem and one or the other is activated for either forward or reverse. It doesn't have a mechanical interlock. Why not change the jumpers so that both contactors are activated for reverse and neither for forward? The coils are 12 volts @ 2 amps. 25 coil watts doesn't seem to be continuous duty, so I built a driver to use PWM after the initial pull in to reduce the current to about 200 mA. The driver works fine and includes the interlocking logic for the throttle. But, I would rather not waste the power since the car goes forward 99% of the time. Thanks, Mike _______________________________________________ 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) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20130410/58fcdb40/attachment.htm> _______________________________________________ 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)
