Power Distribution Block Wiring

Technical Electrical
1

Hi,
We started wiring the Power Distribution block, but the #6 wires keep coming out of the block. Is there a trick to attaching the wire to the terminals or do we just have to screw the wire in tighter?
Thanks in advance!
Team 1015

2

First of all, make sure you back out the screws so the contact is open far enough to accept the wire, then tighten it to the torque specified.

It would be a good idea to look carefully at the metal contacts in the block while turning the screw on top to get an idea of how the thing works.

Don

3

Additionally, fold the the #6 wire over on itself. That’ll provide a bit more material for the locking screw to get a hold of, and some mechanical resistance when it tries to pull out.

4

Some teams put solder in the distribution block holes.

5

I would not make this recomendation. You will never be able to tell if there is something wrong and you will never be able to tighten the screw once it is full of solder. Also, never tin wire you will use in a screw down terminal.

If the #6 keeps pulling out of the terminal there are a variety of reasons. You might need to strip more insulation, it should be 1/4 - 1/2 inch of exposed wire. As Don pointed out above… Check the block before inserting the wire, it might not be fully open. Watch the hardware as it clamps down around the wire as you tighten the screw. It should compress until the wire is tight. It might help to try inserting the wire with the block disassembled so you can see what is taking place the first time. If you examine the block before inserting the wire, you will see that the surface of the contact is serrated so that is grabs the wire. If yours is just a flat surface, it may have been manufactured improperly.

6

Thanks for the info! VERY helpful!

7

We’re having a similar problem with the distribution blocks. We’re able to lock the wires down, but in the process of driving around, the screws will loosen and the wires will then fall out! Not Good!

Any suggestions for keeping the screws tight, short of lock-tite?

Thanks

8

Tsom,
I recommend you secure the wires somewhere near the block so that they won’t move when the robot moves. I am assuming your terminal block is hard mounted to the robot frame so that it isn’t moving as well. Are you using hard copper wiries with a few strands or flexible wire with a high strand count? The hard wire may need to be tightened a few times before it finally conforms to the inside of the terminal block. Give us a report in a few days if these work.

9

Thanks. We’ll check it out. Yes the block is fastened to the bottom of the chassis, and the wire is a high strand count wire. We’re figuring that after tightening the wire down, when the robot drives, the wire moves around with can then flatten the multi-strand wire, causing it to loosen and fall out.

Overall, we’re not too thrilled with these wiring blocks… (wire problems, added weight…)

10

You might try the fold over trick for your #10 connections. The #6 will flatten out eventually and should remain tight. Let us know next week if this helps.

11

We had the same problem at first but if you have your wires zip tied through your board that its on leading to your block you really shouldn’t have a problem with them falling out… also sottering works great.

12

I want to punctuate Al’s earlier statement with regard to not using solder on the wires that go into the power distribution block. These terminals are designed to clamp on clean wire and give the best performance on clean wire. Solder flux does not conduct current and it is likely that flux will be left when you use solder. Soldering the wire may not lead to a low resistance connection if the resulting contact area is small. Strip the wire to a length that stops against the back of the hole, so that the full length of the clamp engages the wire. Don’t double up the 6 gauge wire, and insert 10 gauge wires in pairs to get the best clamping action, being very careful about the strip length, it is easy to get insulaton from a 10 gauge wire into the clamp. If you have a lone 10 gauge wire going into the terminal block, it can be helpful to double it up to get better clamping action.

The number 6 wire going into the maxi fuse block can be problematic because the hole in this block is very large. You might crimp on a ferrule that is soft enough to be crushed by the set screw, to get a good connection here that is hard to pull out. Ferrules are also made to improve reliability of connections in din rails. http://www.americanelectrical.com/wireferrules.htm

Make sure that you zip tie all wiring in your robot to the board that the electrics are mouted on near the termination point with a little loop that provides stress relief. This is needed on all of your wiring, and in particular the pwm cables that enter victors and spikes. Your robot will likely interact vigorously with others and when it gets whacked you don’t want the wires moving.

Have fun,
Eugene