11-04-2011 13:14

Andrew Y.

Re: pic: ummm......what?

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

11-04-2011 14:45

Josh Drake

Re: pic: ummm......what?

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...

11-04-2011 15:02

wilsonmw04

Re: pic: ummm......what?

hmm,
I can't tell what your board is made of but, could it have flexed enough, during a hit, to cause that damage?

11-04-2011 15:07

RMS11

Re: pic: ummm......what?

Quote:

Originally Posted by wilsonmw04 hmm, I can't tell what your board is made of but, could it have flexed enough, during a hit, to cause that damage?

11-04-2011 15:11

BrendanB

Re: pic: ummm......what?

So much win in that 2415 robot its no excuse things started exploding!

11-04-2011 23:52

NorviewsVeteran

Re: pic: ummm......what?

This is why you only let electricity flow through the main breaker, not awesomesauce. They're just not designed to handle it.

11-04-2011 23:56

rabridges

Re: pic: ummm......what?

Well there's your problem. Man that must have been some shot. We can fix it, we have the technology.

11-04-2011 23:58

hipsterjr

Re: pic: ummm......what?

Your breakers could not deflect awesomeness of that magnitude.

12-04-2011 00:14

lscime

Re: pic: ummm......what?

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...

12-04-2011 00:15

santosh

Re: pic: ummm......what?

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.

12-04-2011 08:27

Josh Drake

Re: pic: ummm......what?

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."

12-04-2011 14:23

Andrew Y.

Re: pic: ummm......what?

yea, we lucked out because it seems to have broken into the on position

12-04-2011 14:39

EricH

Re: pic: ummm......what?

Quote:

Originally Posted by Andrew Y. yea, we lucked out because it seems to have broken into the on position

12-04-2011 15:09

David Dawson

Re: pic: ummm......what?

Quote:

Originally Posted by EricH So how did you shut the robot off afterwards?

12-04-2011 15:09

Alex Cormier

Re: pic: ummm......what?

Quote:

Originally Posted by EricH So how did you shut the robot off afterwards?

12-04-2011 15:29

MikeE

Re: pic: ummm......what?

I'm going to take a wild guess that it probably won't pass inspection in St Louis as-is.

12-04-2011 16:02

EricH

Re: pic: ummm......what?

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.

12-04-2011 16:03

Travis Hoffman

Re: pic: ummm......what?

Just blame it on us. We looked at it funny in the semifinals.

12-04-2011 16:16

IndySam

Re: pic: ummm......what?

Quote:

Originally Posted by Travis Hoffman Just blame it on us. We looked at it funny in the semifinals.

12-04-2011 16:22

Travis Hoffman

Re: pic: ummm......what?

Quote:

Originally Posted by IndySam Travis is a jinks! You should have seen what he did to us at SMR!

12-04-2011 20:41

ATannahill

Re: pic: ummm......what?

Quote:

Originally Posted by EricH 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.

12-04-2011 20:50

EricH

Re: pic: ummm......what?

Quote:

Originally Posted by rtfgnow What would you suggest in that situation?

12-04-2011 21:06

David Dawson

Re: pic: ummm......what?

Quote:

Originally Posted by EricH 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.

12-04-2011 21:15

Chris is me

Re: pic: ummm......what?

Quote:

Originally Posted by EricH 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.

12-04-2011 21:26

EricH

Re: pic: ummm......what?

Quote:

Originally Posted by David Dawson 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.

12-04-2011 21:45

David Dawson

Re: pic: ummm......what?

Quote:

Originally Posted by EricH 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).

12-04-2011 22:22

Andy A.

Re: pic: ummm......what?

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.

12-04-2011 22:24

EricH

Re: pic: ummm......what?

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.

12-04-2011 22:46

Andrew Y.

Re: pic: ummm......what?

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.

13-04-2011 00:26

Bill_B

Re: pic: ummm......what?

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.

13-04-2011 00:54

Hawiian Cadder

Re: pic: ummm......what?

This, is why all of our electronics are secured via Zip Tie, and not solid mounting hard-wear, its faster, easier, as secure.

13-04-2011 13:36

santosh

Re: pic: ummm......what?

Quote:

Originally Posted by Andrew Y. 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.

13-04-2011 13:38

santosh

Re: pic: ummm......what?

Quote:

Originally Posted by Hawiian Cadder This, is why all of our electronics are secured via Zip Tie, and not solid mounting hard-wear, its faster, easier, as secure.

15-04-2011 00:17

Billfred

Re: pic: ummm......what?

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.

15-04-2011 02:15

MishraArtificer

Re: pic: ummm......what?

Quote:

Originally Posted by santosh I dont understand the smileys. there is nothing fun or happy about safety issues such as these.

15-04-2011 19:17

Cory

Re: pic: ummm......what?

Quote:

Originally Posted by EricH 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.

16-04-2011 17:37

kiettyyyy

Re: pic: ummm......what?

Quote:

Originally Posted by Cory 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.

16-04-2011 18:20

Bill_B

Re: pic: ummm......what?

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.

27-04-2011 10:17

Andrew Y.

Re: pic: ummm......what?

Quote:

Originally Posted by Alex Cormier Unplug the battery?

Quote:

Originally Posted by Bill_B 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.