Question:Power Distribution Block.
 

Can somebody explain the Power Distribution block that we have to use on the robot this year. I do not fully comprehend its purpose or its functions. If someone could help I would greatly appreciate it.

Thanks,

Pavan.

Re: Question:Power Distribution Block.
 

This diagram provides some incite.

Re: Question:Power Distribution Block
 

Please download the Tips and Guidlines document for a better explanation of the this required part.

Re: Question:Power Distribution Block.
 

Thats easy the Power Distribution Block (PDB) can give 4 things power with only 1 wire coming from the battery. Same with "-" side. The PDB is very useful for getting power to multiple objects but they only give one so use it wisely. I hope this helps.

Re: Question:Power Distribution Block.
 

Don't forget you can use both sides of the block.

Re: Question:Power Distribution Block
 

do we really have to use that gigantic hunk of wasted space?

Re: Question:Power Distribution Block
 

You have to use it, but it doesn't have to be either gigantic or wasted. It's modular. If you don't need all the connections, don't install all the sections.

Re: Question:Power Distribution Block
 

so, i can cut down to one red, and one black section? why not just let me not use it, so i dont have extra space and ugliness on my god plate!!

Re: Question:Power Distribution Block
 

I wouldn't do that. The distro blocks are useful for returning all the high current motors to the negative lead of the battery. You need at least 2 of the red blocks to distribute positive to the Maxi block and smaller fuse panel. Remember, only one #6 wire per terminal. One in and two outs requires two blocks and the jumper plug.

Re: Question:Power Distribution Block
 

The power distribution block is required according to the rules, and you need to pay careful attention to the details when you assemble it, both to satisfy inspection requirements and to minimze voltage drop on the jumper that might also be aptly described as the "fuse." This is a heavy item, so it pays to leave off sections you don't need, but be careful to follow all of the wiring rules and guidelines.

Route your 6 gauge power line (from the breaker) into the block and your 6 gauge power line to the 40 amp maxi fuse block in the same section of the block (opposite sides) so that this high current connection does not go through the jumper. Pay close attention to assembly instructions, and allowed wire counts for the connections, found in the "Battery Power Terminal Strip" document found at http://www.usfirst.org/community/frc...nt.aspx?id=452. I am willing to bet that many teams will guess at this and run into trouble during their technical inspections.

The most critical current handling is for your drive motors, especially if you are using four CIMs on the drive. Your #10 ground lines coming back from your drive motors can be attached in pairs to the ground terminal block, and if you use four motors for your drive you should use two adjacent block sections, feeding the 6 gauge ground line to the other side of one of them.

If I had a spare jumper, aka the "fuse," I would hook it up to TIG welder set for 120 amps or so and see if I could blow it, or at least melt the plastic cover off of it...


Eugene

Re: Question:Power Distribution Block
 

quick question about the block, the yellow center part, can we cut that down to fit because we are not using the full red and black parts we are only using about 1 section of each

Thanks

Re: Question:Power Distribution Block
 

Denise,
Again you need to use the distro block for the high current (40 amp) returns for your four position Maxi block and all feeds to the smaller fuse panels. As to cutting the jumper, there is currently no rule for this part. I suggest you ask the Q&A. Ideally, you should be able to cut this to fit you design, but it would need to be insulated in some fashion as the cut would expose metal that is connected to the battery.

Re: Question:Power Distribution Block
 

If you're only using one section of the distribution block, the yellow jumper piece serves no purpose. It is intended to connect adjacent sections.

Re: Question:Power Distribution Block
 

I would agree that there could be better methods of wiring this. However rules are rules and you can still make a great looking electrical board which doesn't weigh much. We calculated ours to weigh about 11.187 pounds.

My thought on the power distribution block was along the lines of you can do the same thing with the maxi breaker block. Notice it has 3 holes on the incoming. Use one for the main read wire coming from the 120A main breaker. then use the other 2 to go to the smaller panels for the 20A and 30A breakers. However this is NOT legal according to this years rules.

I still say the IFI breaker panel was the best way to go, I am really curious as to why FIRST doesn't approve of it.

Re: Question:Power Distribution Block
 

Thanks!!!

Re: Question:Power Distribution Block
 

I agree with you 100% on both topics about the IFI Breaker Panel and the 3 way Maxi Fuse Block. I'm really infuriated about this because it takes up a lot of space that we don't currently have, however, as much as I hate it, I must follow the rules. I loved the IFI Breaker Panel. It made everything so easy and simple, although I am not sure of the quality of it because it felt like it was going to fall apart when we installed it in 2005. Oh well, there is always next year, I hope :yikes:

Re: Question:Power Distribution Block
 

It makes it more real to life in a way. I mean you never know you could be forced to do something like this in an engineering job. While there may be better methods of doing it, you have to use the more complex method.

Besides this way gives new students a good challenge.

One thing i have always thought is FIRST needs to come up with ways for students to actually start learning stuff about electronics and not just a 12 volt system. The 7.2 volt charger is a good example of this, however they limited it to IFI's design, but for good reasons i suppose. Its just i think students need to start learning some of that stuff... ohms law, how to tell what size resistor you have, what kind fo circuitry you need to make to get this effect, etc.

Re: Question:Power Distribution Block
 

Would it be safe to have just one #6 wire coming out of the power distribution block, into the maxi, and then from the maxi to the ATC panel? (because the maxi has an output for #6)

My guess is that this is not the preferable wiring solution as each "piece" of these power dist. blocks aren't rated for really high current, so it would be better to pass some of the current through another "piece" of the block.

Thanks for the help!

Re: Question:Power Distribution Block
 

There are a few problems here. One is that the four position Maxi has provisions for #2 to #8 wire and that leaves a lot of excess room when you terminate the #6. (It can actually fit more than three #6 wires in the same hole.) All the robot current flows through the first #6 in your question and that will produce a significant drop across even a small piece of wire. Assuming you have about 4 feet of #6 (red and black combined) and you are using 4 Chalupas, at stall the voltage drop could reach 0.8 volts or higher just in the wire. By the time you get around to feeding the RC the voltage may have fallen another 0.5 volts. Since the RC starts to get unhappy at 8 volts, you are starting out the match at 10.5 volts with a fully charged battery under high current demands. The Rockwell blocks are rated at 85 amps continuous current so they can handle high currents for short periods of time like a two minute match. Please watch for heating in the jumper accessory though, it is unrated.

Re: Question:Power Distribution Block
 

Besides i believe that would violate the rules... because you would not be wiring it according to the wiring diagram

Re: Question:Power Distribution Block
 

Sounds like you have given up on trying to get usefull info about the jumper....can't say I blame you....

Re: Question:Power Distribution Block
 

Re: Question:Power Distribution Block
 

you mount them to the din rail that came in the kit. I think its an inch and a half wide and 19 inches long.

Re: Question:Power Distribution Block
 

The First website has a nice blowup pdf that shows all. You can find it at http://www2.usfirst.org/2007comp_173...Strip%20R3.pdf
The rail can be cut down to size for your needs.

Re: Question:Power Distribution Block
 

Anyone know if the grey center divider blocks (or for that matter the gray panels) are required between the red and black? For a 12V system this seems to be overkill to me.

Re: Question:Power Distribution Block
 

To clarify even further. If you orient the blocks correctly the black and red blocks are technically isolated between each other by the wall of the red (or black) block itself. There also is a decent air gap on both sides of the wall, which is easily enough insulation between the terminals.

In the power distribution diagram it appears that there are both panels and blocks used. In between the red and black blocks are both a grey panel and a grey block on the "exposed" side. And also at the far end of the block where it would be "exposed" if the grey mounting block were not there.

So what is required?

Re: Question:Power Distribution Block
 

T,
I am recommending that teams assemble the blocks just as shown. The additional grey (thin) spacers give an extra added buffer between sections in a system that moves around. Just insurance I admit. They are needed when the blocks are used at rated voltages (110-240) for insulation. The grey locking blocks are the same kind of thing. Just extra insurance that the whole assembly doesn't slip and slide around on the rail.

Re: Question:Power Distribution Block
 

Another Question: Is there a better way to attach the 6 gauge battery connector cable that just sticking it into the power distribution block, and tightning it with a screw?

Thanks,

Re: Question:Power Distribution Block
 

Anish,
That is the only way. If you strip about 3/8" of insulation and make sure the wires are twisted tight, you should have no problem inserting the cable. Make sure that you are not clamping down on the insulation. I may work for a while but the wire is guaranteed to loosen and fall out if you do.

Re: Question:Power Distribution Block
 

Al and anyone else...
We were told that there was an issue with these blocks at the PNW regional.
That they were supposed to be used with some type of ferrules that were not provided. This apparently was an issue because wires had a tendancy to slip out of the blocks....

Do you have any information regarding this? Or perhaps a place for us to buy these elusive ferrules to use with the blocks?

thanks
R. Steele

Re: Question:Power Distribution Block
 

Bob,
There are ferrules that are available for stranded wire when used with these blocks. They come in boxes of 100 as I remember. This was a point of discussion by some lead inspectors and the issue with ferrules is the derating of the conductor size by 1 AWG, i.e. a #10 w/ferrule has the current/resistance of a #11 wire. I believe that part of the issue is that teams do not tie down the wires near the block. As the robot drives around and gets banged the wires twist side to side and eventually "flatten out" inside the terminal. I am recommending that teams tie down the wiring and check that the terminals are tight after every match. I am sure you can use the ferrules if you choose, without any difficulty other than an inspector may not know what they are. I think the greater problems will come with teams using one #12 stranded wire per terminal. I would think teams would have far less trouble if they doubled the #12 in each terminal to fill the space (as allowed by manufacturer spec sheet).
Another problem some teams may have introduced is using #12 to wire from terminal block to fuse blocks. If you are a team that mistakenly took this approach, you will need to replace the #12 with #6. You can find a detailed block diagram on power wiring on the FIRST website under the robot rules and within the Guidleines and Tips document. Inspectors will help you if you are unsure.
Hope this helps.

Re: Question:Power Distribution Block
 

Thanks Al,
We have tied down all connectors leading to the block and we don't really seem to have a problem I was just trying to find out if I could lead off a potentially difficult situation for our second regional

We are already using #6 wire.... we would do that anyway in order to minimize any power loss that we can. We always use the shortest route and the biggest wire we can use (within reason) to have the least resistance for our bigger motors to pull current through...

I have been around long enough to know that sometimes problems have a way of showing up during the second time we participate in a regional.
Things have a way of loosening up between regionals and when there was no problem the first time usually my mechanics become complacent...

I will just have to discuss this with them and make sure it is on their initial checklist for the Las Vegas Regional... Next year I would rather use ferrules if we use the same block... AND proper strain relief... this year I looked at purchase and you are correct 100 minimum and pretty pricey... 30-40 dollars with shipping...at least pricey for our minimally funded team...

A little foresight beats hindsight any day...
thanks for your always helpful input!!

Good luck to you

R

Re: Question:Power Distribution Block
 

I did a thorough inspection of our robot after UTC, and found NO loose connections, we did not use ferrules, we soldered the ends of our #6 into a solid conductor prior to installing in the Rockwell blocks. Al is right about derating the conductor if using ferrules, that's why we soldered our conductor ends solid.

I would recommend never relying on a terminal screw style connection when using multi-strand (automotive style) conductor. The strands never fully seat in the terminal and movement allows the strands to move around and loosen up even when torqued properly. Also, the larger the AWG size, the worse the problem will be. Seven or nineteen strand conductor shouldn't have the same problem, our's didn't, but you still might want to solder those, too.

Use ferrules or solder.

Re: Question:Power Distribution Block
 

I would not reccomend using solder on the wiring. As Al suggests, ganging multiple 12 or 10 gauge wires in the terminal blocks is recommended and aids retention. We have been through two regionals and have not had wires pull out. We use flexible high strand count wire everywhere, zip tying it to the board close to the terminal with some stress relief. We check the tightness of the screws on the terminal block now and then and have not had anything loosen, but you really want to tighten to specification torque in the first place and not guess on this.

The one place that we used a "ferrule" was on the 6 gauge high strand count welding wire going into the maxi fuse block for the main motor power. We used a crimp on parallel splice that the wire would just go through, hex crimped it on the wire, and then mashed it to get the right shape for good conductivity in the maxi fuse block.

Ferrules will no doubt help, but you don't need them in quantity 100 and you don't need to pay high prices for them. You can get pure copper tube of the right diameter, cut it to the right length, anneal it, clean it, and then crimp it on the wire before putting it in the terminal block and mashing it. If using ferrules on multiple 10 or 12 gauge wires, it is probably best to gang them in a larger ferrule.

For a source of hardened copper tube that would be easily cut, but then you have to anneal it before using it, see:
http://www.smallparts.com/products/descriptions/htc.cfm
and see the following for "half hard" tube that you might not have to anneal
http://www.smallparts.com/products/d...tions/ttrc.cfm

There is always the possibility of drilling parallel splices to just the right
size. You can also drill soft copper tubing from the hardware store.
Drilling copper is not for the faint of heart, but it can be done.

Eugene

Re: Question:Power Distribution Block
 

Art,
I wouldn't suggest tinning the wire before placing in these blocks, there is no chance for the wire and terminal to confrom to each other. It might help to dip the first 1/8 inch of the wire in a solder pot to hold the strands together. Of the teams that I saw with trouble this weekend, all had failed to trim enough of the insulation from the #6 wire before insertion. #6 wire insulation prevents full insertion into the terminal if it is not stripped back at least 1/2 inch.
The ferrules I referred to in a previous post are very soft and thin copper so that they will conform to the outside diameter of the wire with very little effort. I think that the terminal should be given a chance to "bite" into the wire.

Re: Question:Power Distribution Block
 

Mouser has ferrules in quantity one.

see:
http://www.mouser.com/search/refine.aspx?Ntt=ferrule

They have the crimper, too, for a paltry sum of $217.
Man, it seems like a fellow could make some money
by turning out jaw inserts to fit a cheaper crimper...

Eugene