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.
This diagram provides some incite.
Please download the Tips and Guidlines document for a better explanation of the this required part.
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.
Don’t forget you can use both sides of the block.
do we really have to use that gigantic hunk of wasted space?
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.
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!!
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.
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/content.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
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
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.
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.
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.
Thanks!!!
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:
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.
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!
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.
Besides i believe that would violate the rules… because you would not be wiring it according to the wiring diagram