Distro block, maxi fuse box, and ground stem

[Chris_Elston]

the distribution block and ground stud are required for this years robots circuit

Where do you guys see in the rules where it says the ground stud is REQUIRED?

Instead of using the ground lug, we have used the center "phase 2" of the Allen Bradley Distribution block which is more than enough to hold the current in not better than crimp on ring connectors to a ground stud.

However if someone could let me know if I missed something in the rules about the ground stud "required" I'd like to read it again.

PS: Attached is a very quick sketch I did of what I mean. I hope you guys can make heads or tails of it...

[dez250]

<R22>

"All electrical devices must be isolated from the robot frame; the robot strucure may not be used to carry electrical current. The negative (return) wiring must be electrically isolated (floating) from the robots frame. (The isolated ground arrangement is neccessary due to polarity reversals that occur under certain operating conditions such as motor direction reversals.)"

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Thats one main purpose for the ground stud!

[ErichKeane]

Dez, all that says is that electricity must be isolated from the rest of the system. This could be done with say... the ground wires on the BUSS fuse connector, like my team had up until this thread, or other such things. I dont see how forcing the teams to use lower guage wires (ie, using the distro block ) adds safety.

Up until this, we had straight 6 awg wires running from battery (both terminals) to our fuse boxes, which is easily the safest it can get. Instead, now we need to go to each fuse box with a lonely 10 awg wire, which is going to get a heck of a lot hotter than the 6.

[Chris_Elston]

Thats one main purpose for the ground stud!

My diagram mets the requirments of "isolated from the robot frame". It doesn't say ground stud required does it? The distribution block is a form of isolation is it not?

[dez250]

Originally Posted by chakorules

My diagram mets the requirments of "isolated from the robot frame". It doesn't say ground stud required does it? The distribution block is a form of isolation is it not?

It is and it is not a form of isolation. The way its a form of isolation is it is "isolated" from the frame but then its also not a form of isolation due to the constant flow of electricity right next to it. The point of the distrib. block is to have the center empty with common on one side and hot on the other. The ground stud is to place a common central ground area on the bot which comes directly from the batteries common terminal post.

[Chris_Elston]

Originally Posted by dez250

It is and it is not a form of isolation. The way its a form of isolation is it is "isolated" from the frame but then its also not a form of isolation due to the constant flow of electricity right next to it. The point of the distrib. block is to have the center empty with common on one side and hot on the other. The ground stud is to place a common central ground area on the bot which comes directly from the batteries common terminal post.

That same Distribution block is used in everyday 3 PHASE power applications. It's not designed to always have the center empty, sorry but why would they design it like that?

It's rated to handle any and all equal current as the outer lugs.

Allen Bradley's Mini Power blocks are rated up to 115 AMPS

http://www.ab.com/industrialcontrols...owerblocks.pdf

I am just trying to find out where it says we are required to use the ground lug, when in fact the distribution block is the same if not better.

[Al Skierkiewicz]

Originally Posted by Joe Ross

Al,

Who did you talk to at FIRST that said the wiring diagram is the the rule, rather then a suggestion?

I alerted the engineer I spoke with at FIRST of all the confusion. He agrees that this issue must be addressed. They would rather answer in an official way for all teams to read and indicated that it is FIRST's intention to address your concerns via the Q&A later this week. I can only tell you that in a previous conversation I was told that the electrical blueprint is the way to wire the robot using the parts or stated equivalents provided in the KOP. I, as all of you, hope that some changes will be made in these rules but at this point the ground stud, the distro block, the four way maxi fuse block are all part of the equation and we are building our robot to those specs.
To Chakorules: If you wired according to your diagram, it seems you have added more return wire than needed. I would have run a #6 from the battery directly to the fuse panel ground stud as in years past.
For everyone: Even though I quote individual paragraphs from time to time, the manual is a complete document and needs to be read and referenced as such. I take the electrical blueprint as the manual and the written doc as a description of additional detail to the blueprint.

[Chris_Elston]

[quote=Al Skierkiewicz]
To Chakorules: If you wired according to your diagram, it seems you have added more return wire than needed. I would have run a #6 from the battery directly to the fuse panel ground stud as in years past.[quote]

Al:
Thanks for your reply. If you have a ground lug in the KIT that certainly would have been the best way, lug on circuit breaker panel, to lug on ground lug, to NEG on battery.

If you don't have one and improvise, then a #6 won't fit in the load lug on the Allen Bradley mini distribution block. It does fit fine on the circuit breaker panel lug. The "load side" is only good for #10 or smaller on the distribution block. So that's the reason for more "home runs" to handle the load back to the Allen Bradley mini Distribution block. I didn't try it, but maybe TWO #6 could have fit on the LINE side of the Allen Bradley Mini distribution block, that certainly would have be worth a try.

But I see what you mean by going direct to the circuit breaker panel lug from the NEG of the battery. I was looking at the convenience because both leads of the battery connector would reach our 120 AMP breaker and the Allen Bradley Mini distribution block rather than trying to splice the NEG lead to reach the lug on the circuit breaker panel. Shorter = better with NO SPLICERS...

It's one of those, you gotta do what you gotta do things, but I certainly think it's safe and functions just as well and more importantly will handle all the load requirements with (3) #10s carrying the load.

I hope to see your Q/A, please do share it with everyone in this thread. I would need to know if FIRST is going to put their foot down and run to the hardware store to purchase a homemade 1/4-20 ground lug...

[Al Skierkiewicz]

Chris,
In the past we just stacked two eyelet terminals on the same stud to distribute either supply or return leads. We of course insulate with heatshrink the terminals that are used for either.

Dez,
I have to go along with Chris on the distro block, it is designed for three phase power distro and probably (I can't remember what the label speced) can handle 600 volts block to block without arcing over. I actually like this block for distro and I think many teams will find it very easy to use. It has two failings though, the #6 doesn't fill up the input side (That is why I fold over a 3/8" of the #6 to fully fill the void.) and a less than prudent electrical person will force the #10 into a hole without fully retracting the locking screw. This will invariably result in a few strands sticking out to get into trouble with it's neighbors. Other than the weight, I would like to use this in the future.

[Travis Covington]

I have a slightly different question.

Is the distro block required? Or can we use a slightly different (capable of handling larger wire) distro block instead? It isn't really clear in the rules wether this is illegal or not. (thinking logically, it would be fine as the block we are using has a plastic cover, is larger, and we are running 8 guage wire through it instead of 10)

BUT, we could be totally off base and be required to use the distro block we got in the kit.

Any ideas?

[Al Skierkiewicz]

Although there has been changes made recently in electrical rules (i.e. the drop of the ground stud) the distro block is still in the picture for the moment. Keep checking the Q&A and Team updates for the latest.