Changing Circuit breakers

[Ken Best]

During the year we experienced slight delays with a 4 cim drivetrain responding. It seems like the problem may be traced back to the breakers tripping earlier when hot and more frequently. Cooling them helped and we replaced 2 at the Regional event that seemed to help. Any other teams change breakere between events or on a regular basis?

[Ben Wolsieffer]

You're talking about the breakers on the PDB right? We have used never had to replace these because they wore out due to excessive tripping, but it might be possible that they degrade over time.

I know a lot of teams replace their main breaker if it trips, because they supposedly trip easier the next time, but I don't know if the same is true for the PDB breakers.

[Mr V]

Both the main breaker and the breakers used on the PDB are thermal breakers. Once they heat up to a certain point they will trip. Due to their sealed plastic cases they will trip sooner if they are put back into service before they can fully cool. However tripping a few times does not cause them to trip sooner the next time if they are allowed to cool to room temp. Now if they have tripped dozens or hundreds of times they may become fatigued and trip easier.

[Toa Circuit]

Would a vat of liquid nitrogen be illegal..? Could you use such a thing to quickly cooldown the breaker?

[Nirvash]

Originally Posted by Toa Circuit

Would a vat of liquid nitrogen be illegal..? Could you use such a thing to quickly cooldown the breaker?

Probably would be illegal on safety grounds, and have a chance of damaging the breaker.

[Al Skierkiewicz]

Ken,
You have to add other items for us to best diagnose the issue. Are you using Jags or other controller, etc. I would recommend replacing breakers if they were subject to repeated faults due to shorted wiring, motor or controller. The repeated and rapid trip will cause some pitting of the contacts. However, any team that knows that breakers are tripping should be looking for solutions to a condition that the robot is warning you about. When the robot talks you need to listen. Often the gear ratio you have selected is wrong or there is an issue with the drive train that is causing excessive loss.

[mikemat]

We saw this issue with our 4 cim drive this year. It happened mostly when pushing or trying to turn out of a pin in high gear. If either were repeated through the match, the breakers would get hotter and trip quicker. With jags and CAN this really killed us because we would be completely down for a few seconds at a time. We replaced all the breakers as a precaution, added a fan to the pdb, and implemented some current limits and auto-shifting. That fixed the issue for us.

[kellymc]

We saw this issue at Champs, after a big hit we would loose drive on one side of the robot for 10 seconds, after looking at the logs and checking all the wiring, we could only think to replace the breakers. We replaced all of the breakers on the drive speed controllers and that solved our problems.

[Al Skierkiewicz]

Mike,
The Jaguars fault for over current before the breakers will trip. the Jag fault lasts 3.5 seconds.
Kelly,
The breakers are self resetting and that takes less than a second. If you were loosing control for 10 seconds or more, something else was happening, likely a radio brownout

[mikemat]

Originally Posted by Al Skierkiewicz

Mike,
The Jaguars fault for over current before the breakers will trip. the Jag fault lasts 3.5 seconds.

Yes, we noticed this. We believe running and stalling was heating the breakers to the point of causing them to trip earlier. We saw them trip at stall, but only immediately after matches or hard practice sessions.

[Ken Best]

We are running a 4 cim two speed gearbox w Talons, The high ratio is a bit too much. There are also 2 cims on the shooter arm . It would normally happen if hitting ( pushing) someone in high before shifting. I was pretty much figuring this was the problem as breakers deteriate with heat and at close to spec operation.
A new maintenance manual is due for next year..

[Al Skierkiewicz]

Originally Posted by Ken Best

A new maintenance manual is due for next year..

??? Yours or ours?

[Ken Best]

Ours, we're keeping it under wraps.

[kellymc]

Originally Posted by Al Skierkiewicz

Mike,
The Jaguars fault for over current before the breakers will trip. the Jag fault lasts 3.5 seconds.
Kelly,
The breakers are self resetting and that takes less than a second. If you were loosing control for 10 seconds or more, something else was happening, likely a radio brownout

That's why we couldn't understand it either, based on our logs we were not having a radio brownout, once we replaced the breakers we never had the problem again, It seems unlikely that the breakers were bad, but not knowing if the one's in the robot were from the 2014KOP or were old one's taken off the shelf

[Al Skierkiewicz]

Kelly,
In my experience, these breakers do not die a slow death. They either work or they don't. When tripping for a sustained short they can actually buzz they reset that fast. When they buzz they get extremely hot. Be careful when touching breakers, you may end up having "30 amp" burned into your finger for a few months.