Illegal use of springs?

[HotWheels2002]

Does anyone know if a team is allowed to keep a breaker from tripping using a spring? We had an inspector say "no way" after having used this idea for the past four years or so.

(PS - I am not part of the electronics sub-group on the team, so the closer to common knowledge vocabulary that the responses are, the better.)

[Al Skierkiewicz]

You should not be able to prevent a breaker from electrical tripping by holding the handle. This is a saftey feature required on breakers to prevent homeowners from burning their house down by holding a tripping breaker in the "ON" position. It may help with impact tripping but as I remember in our tests it did nothing to prevent trips of any kind. Read the discussion of breaker construction in the robot appendix.
Good Luck

[HotWheels2002]

I figured that was the case....I wonder why we were forced to remove that spring before competition at Rugers? After some small electrical problems at VCU, we were trying to take every precaution to prevent these problems. Thanks Al.

[Al Skierkiewicz]

Anytime, glad to help.

[ECarlson]

Originally posted by HotWheels2002
Does anyone know if a team is allowed to keep a breaker from tripping using a spring? We had an inspector say "no way" after having used this idea for the past four years or so.

(PS - I am not part of the electronics sub-group on the team, so the closer to common knowledge vocabulary that the responses are, the better.)

I think at the 2001 kickoff, one of the presenters mentioned that you might want to install a device to keep the breaker from tripping due to collision forces, so a spring should be acceptable for that.

We never had a problem of the breaker tripping that way, but some teams do put in preventive devices.

[Teedoff101]

We used a spring like device to keep our breaker from tripping -- but we used it as a shock absorber between the breaker and the frame, not holding the switch.

[ECarlson]

Originally posted by Teedoff101
We used a spring like device to keep our breaker from tripping -- but we used it as a shock absorber between the breaker and the frame, not holding the switch.

Clever idea. Did the springiness make the switch harder to turn on and off?

[Greg McCoy]

It seems like that sort of setup would be perfectly legal, as long as you used allowable parts and did not modify the circuit breaker.

[Jnadke]

They should have no reason for stopping the switch from tripping. The breaker trips internally and has nothing to do with the switch...

[Gui Cavalcanti]

Our breaker is mounted to lexan on the top of our bot so that just the switch pokes out of the top. We use velcro straps (with stick velcro on the lexan itself) to hold the breaker in the on position.

We don't really do this for electrical reasons... I can't see us pulling down more than 60 to 70 amps continuously anyway. We do it because the breaker is on top of the robot and that's where balls tend to come down on... I know, we should have rethought the system, but it was far too late to move the breaker to a convenient location.

[ahecht]

Originally posted by ECarlson


Clever idea. Did the springiness make the switch harder to turn on and off?

I'll answer that. As a quick fix before inspection, we unscrewed our breaker from the frame, laid a piece of latex tubing down flat where our breaker was, and screwed the breaker back down on top of the tubing. This whole operation took less than five minutes, and we never had the breaker trip after that. It didn't make the breaker that hard to switch, as the latex could only be compressed half a centemeter at most.

[ECarlson]

Originally posted by ahecht


As a quick fix before inspection, we unscrewed our breaker from the frame, laid a piece of latex tubing down flat where our breaker was, and screwed the breaker back down on top of the tubing.

Another good, and easy idea.

[HotWheels2002]

Originally posted by ECarlson


Clever idea. Did the springiness make the switch harder to turn on and off?

Actually, we had the other end of that spring around a bolt that we mounted off of our battery carrier. The spring never had to come off of the switch, rather it came off of the bolt when we turned it off (the distance between the bolt and the breaker switch was just a bit more than the length of the spring to make it tight). The whole on or off process took maybe 8 seconds (we'd simply take the end of the spring off of the bolt).