Transformer Wire Current Capacity

On 9 May 2006 17:26:24 -0700, "Tom Bruhns" Gave us:

I wound transformers in an engineering lab for 8 years, I know when to use Litz.

I am talking about the frequency in question here, not switcher basics seminars.

and it pops up at 50/60Hz, too, where skin depth in Cu is around 9mm. It usually wont make an appearance until you get to mains distribution size (LOTS of Cu, many layers), but I've seen it myself in a small 600A coupled 3-phase choke.

M.P. Perry's book, Low Frequency Electromagnetic Design, is a must-read. See fig. 2-11b - "1,600A carrier current line trap in 230kV substation", concentrically wound with varying-thickness conductor, specifically because of skin/proximity effect.

Ever heard of "Roebel" transposed cable? fig. 3-5b - rectangular strands which are transposed every 10cm or so. Often used in BIG transformers and generators......

Cheers Terry

It's only out by an order of magnitude. In some fields, that's pretty good.

It's interesting to see that lighter guages are not rated to carry any current. I wonder what they are good for?

I don't mind spelling mistakes, just so long as they're consistent.

RL

Ratings for power transmission conductors are grossly underrated. The reason for it is not only fire safety, but also the fact that lighter gauge means more voltage drop, which means cost to consumer.

Without conservatve code requirements, builders would skimp on wire, causing more expense to the consumer in the long run. The code protects electricity consumers by demanding heavier gauge wire that could be gotten away with.

This does not apply to microwaves.

There, there, John, we all know "gage" is a noun. :-)

Cheers! Rich