Large CIM breaker trouble

[Cody Carey]

I've searched and come up with some interesting threads... but as far as I can tell, this is the only question like this Sorry if it isn't

We attached the large CIM for our motor today, and We continually Flip breakers before it gets up to speed. We tried switching joysticks, and it helped for a throw or two (which doesn't make sense to me). When we slowly ramp the speed up, It gets to a higher RPM before blowing the breaker, but the breaker still flips.
We went back and made sure that nothing mechanically was binding, and everything was fine. We also did a check of our electronics, and everything is fine, except that we are temporarily using a smaller wire than we should. I would think that using a smaller wire would cause the breaker NOT to flip... But at this point I'm out of Ideas. We made sure to use the correct everything but wire running from the motor to the speed controller. The wire leading to the large CIM is coiled next to the 4 small CIMS we use, and when we aren't running them... It seems that the problem's severity lessens. But I don't know...

Any ideas would be greatly appreciated

[Andrew Blair]

In addition, its a 40 amp breaker we're using.

[Joe Ross]

Does it happen when the motor is not connected to anything (mechanically)?

[Kevin Sevcik]

I assume this is for a shooter. How big and heavy of a wheel are you using, and what gearing are you using?

Also, it only working for a throw or two makes perfect sense. The breakers are thermal buildup sort of devices. If you look at the spec sheet, they're only guaranteed to trip at 135% overload. If you're operating between 54 and 40 amps, then the possible trip time is 6 seconds to infinity. So you might be drawing enough amps to make it trip after 15 seconds or more. Or you might be spiking it with 70 amps or something for a few tenths of a second, but the heat isn't dissipating, so it'll trip after a few of those spikes. It sounds to me like you're trying to drive too large a load with too much voltage, really. I know my team is planning on adjusting our maximum commanded PWM based on the RPMs of the CIM to keep from tripping the breaker.

[Al Skierkiewicz]

Cody and Andrew,
This is an odd case but there is a good way to check out all the possibilities. First, have you tried a different breaker, there are production problems from time to time. Second, disconnect the motor wiring at the output of the speed controller and power up. If the breaker still trips, it is the speed controller or the wiring feeding it (double check the speed controller is correctly wired.). Third, replace the wire between the motor and the controller, using the smaller guage may have melted the insulation between conductors somewhere causing a short. Finally, you could have a bad motor or the mechanism the motor is attached to has a mechanical problem.

[robotoby35138]

do you reset the breaker or just the robot because that is what we had a problem with?