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Unread 12-02-2009, 10:41
ErichKeane ErichKeane is offline
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Re: Solving static electricity problems by grounding the frame

Quote:
Originally Posted by EricVanWyk View Post
I don't either, I think this reason is simply wrong.

The other reasons I still agree with.

In any case, grounding the chassis is illegal in FRC.
I realize it is illegal, I was going to ask for a rules clarification in the Q&A, but in reading through here, I'm convinced that is what the rule means.

I just still haven't heard a single reasonable reason why grounding the frame is a bad idea. If car bodies are grounded because it is cheaper, why don't higher end cars electronically isolate the bodies if it is at all safer? The reason is that grounding the body has some huge advantages, 1st- It prevents static (which is especially unsafe in fuel-based vehicles), and 2nd- it isolates, identifies and removes any shorts immediately through smart fusing.

Another household device which has the body grounded is your computer case, for the same reasons. Most metal cases are grounded (as are many laptop cases, if not, at least the trays) for these reasons, and the computer manufacturers don't face huge risks from awry wiring! Again, it is to protect the user.

The ONLY somewhat reasonable reason i've seen so far is the delicacy of the cRio. In a grounded system, it is possible that a positive short to a grounded frame could cause problems with it. However, that begs the question: why isn't the cRio designed with removable diodes to prevent this problem?

We've already seen that the cRio is susceptible to ESD (a WHOLE 'nother rant!), which should be avoidable if ITS frame was grounded.

As for two vehicles exchanging electricity in a collision: the only way this happens is if the positive cables touch. Vehicles touching grounded bumpers happen all the time, and I've never seen, nor heard of a single one causing computer/fuse issues. Again, the only situation this causes a problem, is if one has a positive short that touches another ground.


So I guess this discussion has dropped into an academic one (since FIRST's rule, is FIRST's rule). Does anyone have a plausible true reason why this would cause an issue?
 


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