Our Power Distribution

[mjgard]

We are a rookie team and wanted to see if anyone had any concerns with our electrical so far. I would hate to get to the competition and have to change something. We just dont have the circuit breakers in yet.

[vhcook]

Looks really good.

You'll also need to attach your PWM cables to the victors and spikes. I usually protect the positive connection to the ATC panel with some electrical tape, since it's so very close to a negative terminal and a loose screw (or finger) could easily cause a short there when it's energized.

I hope you've selected a mounting location that leaves enough clearance to get the serial cables in and out since those ports seem to be right at the edge of the lexan. IFI recommended last year that the radio modem be mounted vertically, and I see it's not on your board, so I assume you've chosen a suitable location elsewhere on your robot.

[Otaku]

Looks pretty clean, but what's up with the weird bends in the negative wire down at the bottom? Also, PWM connections and Vic Fans power should be taken care of.

[MrForbes]

Very nice!

Some things we can't tell from the picture: Along with the concern about being able to plug in the cables, you might want to make sure the motor connections at the Victors are not too close to something, or it will be kind of hard to work on.

And just to double check...at the distribution block, did you make sure to strip 5/8" of insulation off the wires, and tighten the set screws firmly? If you dont strip off the full 5/8" and insert them fully into the block, then you could have problems with the wires falling out.

[mjgard]

The bends in the negitive wire are because it is going around an area that our battery will sit into and we have already connected the victor fan power. We just bundled the wire near the fans to keep it clean. We havent attached the PWM cables yet so we could get a review of the electrical system first before adding even more wires. The back of this panel goes into an open area with no problem to access the serial ports.

[Drwurm]

*Cough* looks a lot better than my first wire job *Cough*
phew, excuse me.

All you need to do is route your PWMs, and it looks like that will be a pretty simple task. Great job for a rookie team.

[Gamer930]

Looks like a perfect electrical board in my mind. You are allowed to cut the wires on the fans to shorten them up. That will clean up the rabbit ears/bundle.
Really like how you have the pretty short 6AWG wire runs. You really took into account on how you were going to wire things when you were designing the board.

[Al Skierkiewicz]

Michael,
This is an excellent layout and very well wired. It should work fine. If you don't mind, can I point out a few things that will make it even better?

1. The Maxi block could be turned 90 degrees clockwise which would allow you to remove at least 6 inches of #6 and allow some straight runs to the Victors.
2. If you notice your wiring on the Distro block, the battery connection is directly opposite your Maxi block feed (very good!) but all the current for the ATA panel goes all the way across the jumper. By moving the three #6 wires to the two center terminals, all the high current loads are then passing through just a short path on the jumper or terminal.
3. Think of the current passing through your black wiring in the same way.
4. Since we cannot see it from here, the Maxi Block is not really meant for #6. If you strip at least 1 inch of insulation from the end of the #6 and fold the wire twice (think in the shape of a "Z", so that it is three times the diameter), it will fill the hole on the Maxi block. This allows you to tighten the holding screw without spreading the #6 wire and it givew you better current flow into the Maxi block.
5. We also cannot tell, but your power leads to the RC should be one of the two terminals closest to the power input to the ATA panel. This point will give the lowest loss/ highest voltage to the RC.

The really excellent part of this picture is the extremely short #6 wire runs. Short wire= less loss=higher motor power.

[vhcook]

Would there be any concern with Z-folding the #6 causing extra stress in the conductors?

(And thanks for that reply, Al. I learn something every time you post on one of these.)

[DonRotolo]

WoW! VERY Nice wiring job! Far better than anyone on our team did in our rookie year.

Some suggestions:

1. If you end up not having to use all the distribution block modules (I see one black and two reds you don't need at the moment) you can remove them to save weight. Do that just before shipping, so you're certain you won't need them.

2. Wire is heavy, #6 wire ie very heavy. Make those runs as short as possible.

3. Ohms cost you power. If you have a motor drawing 40 Amps, and the overall resistance of the red wires from battery to motor is 0.1 Ohms, you lose 4 volts (V=I*R, =40*0.1) to the motor - and trust me, the motors don't work as well at 8 volts... (and, if the same is in the black wires, you get only 4 volts to the motor ) Very carefully check each and every connection and crimp to make darn sure they are as good as they can be!

Label everything, especially the PWMs. Give each spike and voctor a name, for easy identification.

WoW again, I'd be proud to be on your team

Don

[Al Skierkiewicz]

Originally Posted by vhcook

Would there be any concern with Z-folding the #6 causing extra stress in the conductors?

This is one of those times where you have to weigh the pros and cons. There might be a little breakage if you get too aggressive. On the other hand, without filling the void in the Maxi block, when you tighten the set screw, the strands spread out and up the sides of the screw. (try it and see what I mean, some of the strands will actually climb the threads of the screw.) I believe this reduces the connection to the same cross section as a #10 or #12 wire. You will find that people suggest you tin the wire with some solder before insertion. This method on all parts of the the robot is a very bad practice. It reduces the contact area to just the top and bottom of the circumference of the wire making an equivalent in the #16-#18 range. Solder to make a connection better, not to overcome a problem with contact. I should also mention (in case someone has not seen this yet) that the Rockwell blocks require the wires to be stripped 5/8" before insertion. When you insert the wire it should come to a mechanical stop inside the block and it should be obvious that you are not clamping any insulation when you tighten the screw. If done properly, the wire will not pull out and you should have no exposed wire past the outside of the block.

[mjgard]

What size breaker is required for the robot controlor and the spike? Any thing special for wiring the compressor to the spike? Wiring it to the spike is correct?

[MrForbes]

See rule <R55>, which says that the compressor and spikes and controller all take a 20 amp breaker.

Make sure you wire the positive and negative to the correct side of the spike, and program it to drive the spike with the correct polarity.

And just to eliminate confusion, the side of the spike that says "12V" and "NEG" goes to the fuse block, and the side that says "M+" and "M-" goes to the load (compressor).

[Al Skierkiewicz]

Don't forget that you may/should replace the 20 amp fuse in the Spike that feeds the compressor with a 20 amp self resetting circuit breaker. The start current on the compressor is 25 amps (run is 10-12) and guaranteed to blow the fuse eventually.

[mjgard]

can these 20 amp breakers be purchased at a local store or only from ifi?