View Full Version : pic: ummm......what?
Andrew Y.
11-04-2011, 13:12
[cdm-description=photo]36799[/cdm-description]
Andrew Y.
11-04-2011, 13:14
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
Josh Drake
11-04-2011, 14:45
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...
wilsonmw04
11-04-2011, 15:02
hmm,
I can't tell what your board is made of but, could it have flexed enough, during a hit, to cause that damage?
hmm,
I can't tell what your board is made of but, could it have flexed enough, during a hit, to cause that damage?
board is 1/8" aluminum with minimal cutouts, doubt it flexed that much...
BrendanB
11-04-2011, 15:11
So much win in that 2415 robot its no excuse things started exploding!
:yikes:
NorviewsVeteran
11-04-2011, 23:52
This is why you only let electricity flow through the main breaker, not awesomesauce. They're just not designed to handle it.
rabridges
11-04-2011, 23:56
Well there's your problem. Man that must have been some shot. We can fix it, we have the technology.
hipsterjr
11-04-2011, 23:58
Your breakers could not deflect awesomeness of that magnitude.
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...
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.
Josh Drake
12-04-2011, 08:27
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."
Andrew Y.
12-04-2011, 14:23
yea, we lucked out because it seems to have broken into the on position:)
yea, we lucked out because it seems to have broken into the on position:)
So how did you shut the robot off afterwards?
David Dawson
12-04-2011, 15:09
So how did you shut the robot off afterwards?
I'm guessing they pulled the battery.
Alex Cormier
12-04-2011, 15:09
So how did you shut the robot off afterwards?
Unplug the battery?
I'm going to take a wild guess that it probably won't pass inspection in St Louis as-is.
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.
Travis Hoffman
12-04-2011, 16:03
Just blame it on us. We looked at it funny in the semifinals. :rolleyes:
Just blame it on us. We looked at it funny in the semifinals. :rolleyes:
Travis is a jinks! You should have seen what he did to us at SMR!
Travis Hoffman
12-04-2011, 16:22
Travis is a jinks! You should have seen what he did to us at SMR!
;) Maybe the Force is with me? I do hang around with people like this (http://www.chiefdelphi.com/forums/showthread.php?t=94494), after all (the one without the ponytail...wait the Storm Trooper is a girl...I'm pretty sure she had a ponytail too...um, the one without the moustache, then).
Instead of external shock causing damage, what about something internal/structural causing the breakage?
ATannahill
12-04-2011, 20:41
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.
What would you suggest in that situation?
What would you suggest in that situation?
I would suggest a non-conductive poke stick to separate the contacts on the main breaker. Normally, that non-conductive poke stick is the red button. Separate the contacts, then yank the battery, then pull and replace the breaker. In this case, poke on that upper tab-type thing to break connection is where I'd go for first.
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.
David Dawson
12-04-2011, 21:06
I would suggest a non-conductive poke stick to separate the contacts on the main breaker. Normally, that non-conductive poke stick is the red button. Separate the contacts, then yank the battery, then pull and replace the breaker. In this case, poke on that upper tab-type thing to break connection is where I'd go for first.
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.
I have never seen sparks emit from a live Anderson connector. And Ive seen them used to jump start cars. Safety doesn't mean find the hardest way to do something.
Chris is me
12-04-2011, 21:15
I would suggest a non-conductive poke stick to separate the contacts on the main breaker. Normally, that non-conductive poke stick is the red button. Separate the contacts, then yank the battery, then pull and replace the breaker. In this case, poke on that upper tab-type thing to break connection is where I'd go for first.
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.
And you don't think there's a greater chance that poking a fuse with a stick will unintentionally cause a short than unplugging an Anderson connector?
I have never seen sparks emit from a live Anderson connector. And Ive seen them used to jump start cars. Safety doesn't mean find the hardest way to do something.
I've seen a plugged-in FRC battery spark. I forget whether it was the Anderson or the terminals, but I seem to recall that the area around the Anderson fused (read: welded) to something else before someone could get in there and separate the battery from whatever it was connected to (thankfully, not a robot in that case).
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.)
David Dawson
12-04-2011, 21:45
I've seen a plugged-in FRC battery spark. I forget whether it was the Anderson or the terminals, but I seem to recall that the area around the Anderson fused (read: welded) to something else before someone could get in there and separate the battery from whatever it was connected to (thankfully, not a robot in that case).
What you just described wasn't a Anderson short circuit. If two power poles fused together a wire had a short or the system drew too much current. Anderson terminals are designed for safety and useability which is why they have shielded contacts. If you really want to get technical even if there was a slight spark between the power poles it would take the path of least resistance (i.e not your hand) for the milliseconds it would have before the connectors were far enough apart. I would take my chances with this before touching a broken exposed circuit breaker.
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.
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.
Andrew Y.
12-04-2011, 22:46
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
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.
Hawiian Cadder
13-04-2011, 00:54
This, is why all of our electronics are secured via Zip Tie, and not solid mounting hard-wear, its faster, easier, as secure.
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
I dont understand the smileys. there is nothing fun or happy about safety issues such as these.
This, is why all of our electronics are secured via Zip Tie, and not solid mounting hard-wear, its faster, easier, as secure.
The breaker and the cRIO are the only things that we dont have ziptied down. Im still not 100% sure it was because we got hit hard a few times. But it is definitely a possibility
Billfred
15-04-2011, 00:17
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.
MishraArtificer
15-04-2011, 02:15
I dont understand the smileys. there is nothing fun or happy about safety issues such as these....I believe the smileys were directed at the incredible circumstance of him and the Occupational Safety and Health Administration guy actually agreeing on something.
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.
Don't be overly dramatic. I've seen this done hundreds of times. No problem.
The simplest way of doing things is usually the best. No need to concoct some scheme when you can just do this.
kiettyyyy
16-04-2011, 17:37
Don't be overly dramatic. I've seen this done hundreds of times. No problem.
The simplest way of doing things is usually the best. No need to concoct some scheme when you can just do this.
There's little to no current being sourced while the bot is still booting up... There should also be little to no current if you're some how up close to the bot without it running around.
Those "sparks" really only fly when you're dealing with MUCH higher potentials(200 VDC++).
It's no big deal.
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.
Andrew Y.
27-04-2011, 10:17
Unplug the battery?
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.
a little late, but i will comment...
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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