Windings too wide for bobbin?

[cupoftea]

Hi,
Cust sent us 500W full bridge to build and test.
They spec a txformer of
15:6:15 ie np/ns = 30/6
they want pri of 0.315mm diam and 3 strands.

But 0.315mm enam copper wire is 0.367mm diam in max tolerance.
So 15 turns would be 15 * 3 * 0.367mm = 16.5mm wide
But RM12 bobbin is only 14.6mm wide.
So do you agree...they cant do this?

 

[wwfeldman]

what happens if you twist the three strands together, then wind the twisted group,
instead of winding them side by side?

assuming an equilateral triangle of three 0.315 (0.367) mm diameter wires,
the side of the triangle is 0.367 * 2, not 0.367 *3, so that will likely fit across the bobbin.
it will add height to the layer, (0.367 * 2 * root(3)/2 or 0.367 * root (3) ) so it may not fit on the bobbin vertically