conductive copper strips

For that kind of current, you want a conductor about the same as 4/0 AWG. If you're only doing it intermittently you may be able to get away with smaller, but if you've got high peak currents (remember heating goes like current squared) you may want larger. That's about a half-inch diameter solid wire.

A copper strip with the same resistance per foot would be 1" wide by

3/16" thick.

That seems like a lot of work, and you don't have the advantage of flatness at the end for the terminations (which is why you're using copper strip to begin with, right?)

Copper strip is available from lots of places, e.g. MSCDirect.com has

1" x 3/16" copper bar at about $6/foot and that's not too far away from buying copper at the commodities market :-).

Tim.

I was actually going to say MSC or McMaster but didn't know if you were familiar with them and MSC's web address is harder to remember (paper catalog is easier to get though!)

That's like 350 circular mils per amp (assuming 200 real amps) which is not at all conservative, those wires are gonna get real warm in even intermittent operation.

I suspect many welders are rather optimistically rated, maybe 200A welders usually only peak out around 100A or something. (Like the ratings on consumer power tools, where they base HP not on max power but rather max torque x max rpm, when they never max at the same time!)

Tim.

Stuff like this is a lot easier to work with.

You can crimp, clamp or solder large lugs on the ends for connections.

Mind the wrap.

Obviously, you'll have to figure out the ampacity for what cross-section to pick.

Good Luck! Rich

I wanted to make a set of chessmen using ammo pieces but I am up in Canada so I would have to use rocks instead.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

void _-void-_ in the obvious place

I need to make a few copper strips (to connect IGBTs to power terminals and to each other nicely). I would like to know where to get them, I searched the obvious places and found none. I have a few strips from a demolished 5 kVa UPS, but not enough. I need them to be able to conduct 200-400 amps.

I wonder, if all fails, can I make my own from regular copper pipes by flattening their ends and drilling holes. At least I can get those at my neighborhood hardware store. Any thoughts?

i

Thanks. I would actually prefer something rigid, it will make certain things easier and safer. It would also save me money on terminal lugs, which I would not need in this case since I can just drill holes for screws.

With copper strip, all I would need is cut it to size and drill holes. Easy. With copper pipe, all I need is cut it to size, FLATTEN ENDS and drill holes. Also easy, although not as pretty as copper strip.

With that flexible braided stuff, I would need to buy a lot of terminals, a crimper, solder etc etc. Too much work.

The power circuits that I have seen (in several UPSes that I took apart) all used copper strips. Unfortunately, I did not save enough of them.

i

I read in sci.electronics.design that Ignoramus18971 wrote (in ) about 'conductive copper strips', on Wed, 9 Nov 2005:

Why not? It's by far the cheapest and most convenient way. I have a store of recovered copper water pipe for such purposes. You can also make bracelets and decorative items with the copper.

I want, one day, to make a set of chessmen, with half of them silver-plated. Very cheap, but very impressive if I do it right.

--
Regards, John Woodgate, OOO - Own Opinions Only.
If everything has been designed, a god designed evolution by natural selection.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

I found some at McMaster, McMaster item 8964K721. 1/2" wide, 1/16" thick, and 6 feet long, only $6.77 each with very modest shipping (I just verified that by calling their operator). I will simply buy one and be done with it. McMaster is just 15 miles from my house and so I will get it this week.

i

Yep, thanks, found mcmaster item 8964K721, 1/2" by 1/16" by 6 foot long. I will simply buy it.

i

Thanks... I found that mcmaster sells copper strip at very sensible prices ($6.77 per 6 foot of 1/2" by 1/16" strip), I will just buy it and have it on Friday.

i

My welding machine (where I will use these strips) works just fine with 1 gauge wire (which is what I use for welding leads). So, I need to find something along the lines of 1 gauge (not 1/0).

Seems like I mistakenly specified too much current. This is a 200a welder that could have some current spikes, but is normally limited to

200 amps.

You are right. I found something at mcmaster, and since I need to buy other stuff from them, I will order that strip. The money is negligible.

i

According to my quick calculation, 200 amps would induce heat output of 192 watts in 40 feet of 1 gauge wire. I used a number of 0.1239 ohms per 1,000 ft, from some table. I can live with that, I think.

The wires are either on the floor or hanging in the air on the wire hanger that I made.

That's why I do not like consumer power tools, "maximum developed HP" on compressors etc. :)

This is not a consumer tool, it is an industrial welding machine rated for 100% duty cycle (is able to weld at 200A nonstop).

i

Table for heavier wires at:

--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

According to my calculations, two 1/16" by 1/2" strips in parallel should be about right for me.

i

The strip that I bought (12x1.5mm) is made for electronic applications.

i

I would go for the busbar type copper strips from a firm selling electric power equipment. They are made of very low resistance copper, they even supply screws and washers made of the same copper,so you can minimise contact resistance. Those bars can have pre-drilled holes with thread.(at least in my country) -)-).

Burry. Netherlands.

Good. Copper water pipe is probably not as conductive as the copper used in busbars. I heard (but have no evidence to support) that the conductivity of some copper alloys used in pipes etc. is only about half as good as electrical grade copper. Of course you can just use a thicker cross-section, but electrical grade copper is a nicer option.

Chris