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pic: ummm......what?
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any thoughts on how this happened? no way it was hit directly as it is tucked very well.
There are little pieces of breaker everywhere |
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When you said in exploded, I guess you weren't exaggerating. They were hitting hard, but like you said it's down inside the chassis. Did the roller claw go down into the base? I doubt it...
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hmm,
I can't tell what your board is made of but, could it have flexed enough, during a hit, to cause that damage? |
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So much win in that 2415 robot its no excuse things started exploding!
:yikes: |
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This is why you only let electricity flow through the main breaker, not awesomesauce. They're just not designed to handle it.
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Well there's your problem. Man that must have been some shot. We can fix it, we have the technology.
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Your breakers could not deflect awesomeness of that magnitude.
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Scotty: "I'm giving her all she's got, Captain!"
Kirk: "All she's got isn't good enough!" And this is why you should always listen to the engineer... |
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343 did knock the crap out of us a few times. they had some great driving in that last match. but i still dont believe that the chassis could flew enough to cause that.
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I looked at the video of the last finals match and expected to see 2415 get hit near the end and then die. The breaker was still working the entire match. 2415 deployed the minibot like normal. "It's just a flesh wound."
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yea, we lucked out because it seems to have broken into the on position:)
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I'm going to take a wild guess that it probably won't pass inspection in St Louis as-is.
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Unplugging the battery when the circuit is on carries a risk of sparks, guys. I would not suggest trying that--ANYWHERE. That's why I asked.
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Just blame it on us. We looked at it funny in the semifinals. :rolleyes:
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Instead of external shock causing damage, what about something internal/structural causing the breakage? |
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I've seen the sparks that can fly when there's marginal contact on a battery to some other connection (charger, bolt, other battery). They may look pretty, but you don't want to see them because they mean something's wrong. |
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Chris, the thing about using a non-conductive poke stick on the connector is that 1) you only get one place for a spark (the breaker, which in this case is already broken) as opposed to 2 (each side of the Anderson) and 2) your hands are not right there to risk getting zapped. I don't know about you guys, but I'm not sure I'd want my hands right next to a fully-live FRC battery's current and voltage if I had to unplug it, even with an Anderson connector between my hands and the wires. (By fully-live, I mean current is flowing actively, not current can flow if the connection is made.) |
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Under the circumstances, disconnecting the battery would have been the safest thing. The priority should be to depower the robot, and the very busted up breaker, ASAP.
While not good practice, breaking the connection at the Anderson while the robot is 'live' isn't particularly hazardous to operator or robot. By design, any arcing will occur while the Anderson is still enclosed. So while it may score the contacts a bit, that's the worse case scenario. As long as it's not an every day occurrence you won't notice. |
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David, IIRC, it was some form of short circuit. It's been a few years, but it was in a row of batteries that were charging. I looked around to see several people rush over to try to figure out how to disconnect the battery that was throwing sparks. Like I said, it's been a few years, so I forget the details like what exactly fused to what.
Also, I never said to touch the circuit breaker with your hand. I said to use an insulated poke stick. That way, there is zero chance that electricity goes to your hand. |
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eric, thanks for your point of view...but my professional experience and my advisors at work all agree my kids took the correct action by unplugging the battery...even the OSHA dude at work agrees...and him and i NEVER agree.
:D :D :D :D :D |
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How does the replacement look now? Look carefully for cracks and feel the smoothness of the new breaker in the places the other one failed. Not sure about your situation, but I have seen Bakelite body terminal strips give out because the mounting holes were ever-so slightly misaligned. Tightening the mounting screws for the terminal strip didn't break the strip but it did stress it so that normal usage eventually caused failure. If the mounting hardware didn't slide into place easily or wasn't perpendicular to the mounting plate, then tightening the mounting nuts may have set up internal stresses that were later released by your collision. It would be harder to develop that stress in a more flexible or more compliant base, like wood or lexan.
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This, is why all of our electronics are secured via Zip Tie, and not solid mounting hard-wear, its faster, easier, as secure.
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First it was the digital sidecar at Peachtree, now a main breaker in North Carolina.
If you guys make Einstein, I'm bringing a fire extinguisher. |
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The simplest way of doing things is usually the best. No need to concoct some scheme when you can just do this. |
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Those "sparks" really only fly when you're dealing with MUCH higher potentials(200 VDC++). It's no big deal. |
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You won't have to go very far into Electrical Engineering before you find out that sparks at disconnection are largely due to inductive loads, viz. motors and transformers. Inductors try to maintain current in their circuits. To do that voltage will increase across a switch as it opens and increases resistance. Eventually the switch "wins" and makes a very high resistance in the air gap, but not before a large inductor load tried to jack the voltage very much higher than usual. Sometimes the voltage spike will actually get high enough to cause current to jump the minuscule air gap as a switch opens. Result? Sparks. Not usually a good thing, so quite a bit of E.E. talent has been devoted to this solving problem.
As it applies here, if motors weren't running when you pulled the battery plug, there is very little chance of noticeable sparking. Voltages in FRC robot-land are usually quite low, so bare-skin contact is not a great danger. However, if the hand in contact has metal jewelry or tools in it, the danger of high current short circuit should not be ignored. I sometimes think that a you tube video of egregious electrician's behavior should be made to convince "kids" how easy and calamitous such short circuit "welding" can be. |
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I agree that there is little load when disconnecting the battery. Connecting the battery has a greater chance due to the capacitors charging the instant they are connected. soo basically we are not supposed to plug our batteries in because of spark. @Santosh....ill see you thursday night...and we can duke it out. Selling tickets to see the fight for $450 a seat. |
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