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# What is the diameter of litz wire made up of strands of enamelled copper wire?

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#### treez

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What is the overall diameter of a litz wound wire, made of 5 strands of 0.5mm external diameter Enamelled copper wire? Is it 1.5mm?

I would expect three wire diameters would come pretty close.

treez

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Points: 2
The mean diameter is close 2.5x

treez

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Points: 2
Thanks, when you say the "mean" diameter, I presume you are referring to the fact that the diameter will vary along its length?

The theoretical diameter could be up to 5 * 0.5mm if the wires were aligned side by side on a plane but when bundled into a pentagon (square with one on top) outline it would be smaller. In a real situation the wires would likely be twisted but not retaining a consistent cross section shape. If you are calculating the area occupied by several turns around a core you would also have to take in to consideration the irregular air gaps. Pentagons will tesselate, side by side will tesselate but other wire arrangements won't so you would have to consider worst case scenarios to be sure it would fit.

Brian.

treez

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Points: 2
Thanks, I see what you mean, I believe that 7 0.5mm strands wound in litz fashion would be 3 diameters wide, and no more?

I would calculate a circular strand, that's also the option offered by litz wire manufacturers.

A circular 5 wire strand can achieve circumcicle 2.7x diameter (with respective center void), 7 wire strand is 3x as you probably know.

treez

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Points: 2
in relation to this, ive just realised that Epcos TDK do not give the "bobbin depth" dimension in their datasheet of their PM62/49 core...

PM62/49 datasheet...
https://www.farnell.com/datasheets/1734383.pdf

this is essential to know, so as to work out if you can fit all your winding bulk on to the bobbin. Does anyone know this?

I don't understand your problem. All required dimensions are in the datasheet. I presume you have a pocket calculator supporting substraction.

treez

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Points: 2
I fear The dimension of the bobbin 'lip' cannot be gotten even by subtraction. It only gives the spindle diameter as 29mm....no other relevant diameter is given.

What do you think is the meaning of the 48.5 mm measure?

treez

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Points: 2