Tripping breakers

[Al Skierkiewicz]

Originally Posted by Lostmage333

If the motor is on a 40 amp breaker, it would take 40+ amps for slightly over a second to trip it. The breakers are slow-blow.

Driving in full power with can get close to the 40 amps required to trip the breaker, depending on your gear ratios and stuff. Pushing gets even scarier. If the drive train wasn't built for high torque and it's used in a pushing match, it's possible for it to easily draw 50+ amps. That, over a few seconds, could trip the breaker.

Good thing is these breakers are auto reset, so they'll reset after 2-10ish seconds.

The 40 amp breakers have a similar over current charachteristic and obviously they can handle short duration 600% overcurrent spikes since they do not trip on short duration stalls of the drivetrain. Their reset times are in the order of milliseconds though, depending on temperature. When the breaker is hot, trip times decrease and reset times increase. In reality, a hot breaker will trip at less than 40 amps. Now, I can hear a lot of you thinking "why don't we just cool the breaker?" The case of the breaker is significantly insulated from the active parts inside the breaker so external cooling will do little to extend trip times. However, all teams should be aware that external heating of the breaker will affect it's performance. Don't mount the breaker panel above motors or near the compressor and make sure that all connections are tight and use correct wire guage. Heating of the contacts will conduct heat to breaker internals.