Laminated Busbars

Perhaps not an air gap, but some insulation between laminations would be needed.

Consider Litz wire. An air gap is not maintained but the individual strands are insulated.

The skin layer depth is about 1/3 inch at 60 hz. In a solid thick piece of copper, 63 percent of the current flows in the skin layer.

Copper Laminated Busbars comprise flexibly laminated copper connections that are produced using highly conductive electrolytic grade copper foils & sheets.

These laminated busbar undergo press welding where individual copper strips are fused through applying direct current as well as pressure which results in ensuring minimum resistance as well as in enhancing the product life as well as in reduction of downtime.

Further, these also feature superior mechanical & electrical properties at higher temperatures.

These also feature higher power density as well as better electromagnetic compatibility (EMC).

www.janscopper.com

It was a similar UK site that got me wondering if an air gap or insulation is required or not. I've used uninsulated braided copper many times in the past relying on the manufacturers CCC (ampacity) tables and therefore didn't give it a 2^nd thought.

From the posted answers, you can see that the advantages of insulated bus structures will only become important in AC applications. For DC operation, there is no advantage.

What the hell has that to do with busbar laminations?

Troll alert!

Troll you say?

TonyS > has your question been answered already?

you do need to have an insulation gap. some suggest a sheet of insulating material.

however that is not the best way forward because the skin effect is a phenomenon driven by a magnetic field - and that crosses over through any electrical insulation sheet.

an air gap wider than just a sheet of insulation will serve still better.

reading Cahier Technique No 83 it will help. you may get it from Schneider website in PDF.

We use an air gap for various reasons:-

1. Skin effect as mentioned

2. Better cooling (more surface area)

3. Easier joints - interleaving fishplates

Most calculations assume an equal gap-to-bar ratio, but larger gaps perform better of course. CDA publication 22 is a good reference for anyone reading this who has not seen it.

Within switchgear panels laminated busbars are used because unlike rigid copper bars they can be tweeked to fit terminals that are slightly out of position or alignment. That means the enclosure steelwork and switchgear mounting positions can be made to low tolerances which is much cheaper. Laminated bars are preferred because they have a higher power density and are cheaper to make than braids. For very high current applications like electro plating lines and elecrto chemical cells laminates are also inserted to take up expansion of the main busbars as they become heated. Ω or S shaped laminates connected at the end of or between two long solid bars usually indicates expansion/contraction duty. There is no electrical requirement to have air gaps (or insulation) between the laminates but a small gap is needed for them to flex or they will bind. You can buy laminated bars ready insulated and these have no air gap. When you bend the bars the laminates slide over each other to accommodate the increase in length between the inner and outer layers as they round the bend/corner. When fabricating you should drill or clamp one end then create the bends progressively from the fixed end so that the shims can slide freely over each other. When all the bends are constructed you can then drill or clamp the other end. If you drill both ends first, then after bending, the holes in each of the laminate shims will be out of alignment.