PDA

View Full Version : [Question(s)] Power Distribution Boards / Busses



perigalacticon
07-10-2017, 11:01 PM
Curt is growing up and requires more POWER! Specifically more power to more Places. I have connected components using stranded wires with red "FC" type Insulated Fork Crimp Connectors that are for 18-22 AWG wire, and accept a maximum of a #6 screw, and the forks are 0.245" wide on the outside. Example:
https://m.grainger.com/mobile/product/POWER-FIRST-Fork-Terminal-24C910?fc=MWP2IDP2PCP
I put a LOT of these terminals on my wires, hoping to avoid the immense hassle of feeding stranded wires into terminal blocks. However, I have not found a good power distribution system for these fork connectors! I am really surprised. I have been using some #6 screws so far and clamped all the forks on them with a nut but it's not pretty. There has to be a better way. I would REALLY rather not have to cut off the crimp connectors that I labored for several painful hours to put on. Does any one know of a power distribution board or bus for these fork connectors? Must handle 10 amps or more on outputs.
Thanks!

jwatte
07-10-2017, 11:36 PM
I've fought the same problems for a while, and come to the conclusion that you either have to over-engineer it a lot, or you end up running wire into screw connectors. Whether it's stranded or not is up to you :-)
(Also assembly paste may help if you worry about intermittency from stranded wires to terminals: http://amzn.to/2ucoI7Y )

If you do want to engineer it, there are all kinds of nice connectors, including combined power-and-signal, to be had. In addition to being expensive (20 dollars per mating pair with housings and pins is not uncommon) you also get some cost in start-up tooling, unless you want to take a chance on some existing crimp dies/tongs you may have laying around.
Then there's the question of distribution, in which you either choose a PCB/cable connector pair, and build a PCB distribution panel (filling whole layers lets you carry a lot of current!) or end up soldering/splicing five-way cat tails.

All the connector manufacturers have their own systems (Molex, TE, Amphenol, Phoenix, and so forth.)
That being said, crimped spade connectors and screw-and-nut retainers drilled into conductive bus bar (aluminum or copper) would probably do just fine! Assuming you can mount the bus bar in a well insulated manner, so you don't accidentally release the magic smoke. Exposed conductive metal is a short waiting to happen :-/

For one use case (the portable control station in a Pelican case) with a plywood main mounting board, I actually ended up mounting square-D ground bar onto the back of the plywood for each rail, and ran cables to each of those bars. For fixed installations, bus bars with screw connectors are pretty typical.

Finally, "10A rated for electrical wiring" is different from "probably runs 10A fine on a hobby robot." For a typical motor that wants 2.5A continuous but 10A temporarily, a 3A rated contact is usually just fine. Same thing with wire sizes; it's amazing how much you can sink through a 22 gauge wire if it's short and it has moving air to cool it :-)

perigalacticon
07-11-2017, 12:13 AM
Thanks, I have searched a lot for a bus bar with screws that will accept these terminals but none I found will take them the screws are usually larger than #6. Unfortunately I can't use the next size larger fork terminal because it doesn't take the smaller wire sizes I have. I guess I'll try to make a bus bar. Thanks again. Forgot to mention it a 12VDC system.

jwatte
07-11-2017, 11:38 AM
A drill press, a drill bit, and a hand tap can make bus bar out of a chunk of aluminum or copper pretty quickly :-)
Or just a cordless drill, and make sure you keep everything still and firm as you run it to avoid snapping tools.

One trick is to mount the tap in the drill press, and manually turn the chuck to cut the thread. The press column will make sure the tap goes straight into the hole, without an angle!

http://amzn.to/2v8Gg1h
http://amzn.to/2ta8jvy
http://amzn.to/2v92wIj
http://amzn.to/2v8UPBS
http://amzn.to/2v91Z9o