Testing for an open ciruit in a DC motor
 

Hi folks,

I really need to ask a dumb question; My pwm-controller (sevcon MOS90) diagonstic led flashes 5 times when selecting drive. According to the manual that could mean an contactor problem or "open circuit motor". I connected + and - from the batteries to the motor and it runs bothways. I presume that there's no open circuit in the motor but I'm not entirely sure...

TIA

Amro

...if the problem is not in the DC-motor, then it's either: (1) in the cabling between the controller and motor, or (2) in the controller itself, maybe one of the output device(s).

I've checked the wiring a couple of thousand times. I 'm going to redo the wiring setup today, i've also checked the contactors. Nothing seems to short circuit them.

I've found a used potbox for this controller and measured it; 5k ohm to zero ohm. Works fine.

My original question is if the motor runs straight on the batteries, it is not short circuiting, right ?

I hope it's not the controller. It would make me very unhappy...

Correct. Neither a short circuit nor an open circuit.

What if you unhook your controller's +/- output cables and attach them directly to a battery? That ought to test your cables, wiring, and contacts.

Won't that just blow a fuse ? Didn't have time to try it yet. Maybe tommorrow I have a narrow window of oppertunity in my garage. First things first, redo the wiring, fix the controller position and if all fails drive by the electric forklift repair/demolishing guy... Before saturday 14:00

Well found the problem and fixed it. It was really stupid, I was convinced the problem lay somewhere in the control wiring but it turned out one of the cablelugs (?) of the motorground had slipped off. But stayed quite securly in the protective tape I'd used. So, no contact, hence the open circuit indication.

Still got some mechanical problems to solve but I think I can get it finished in time to participate in the Dutch National Motorcarier Championships (NBBK) 2010

Thanks for the advice and I'll post some pic's