T
Terry Given
- Jan 1, 1970
- 0
Joerg said:Hello Joseph,
Mostly to avoid corona or arcing. Far enough away from the winding it
isn't so important. Another concern is if the wire is to be wound
directly onto the bare or taped core. Any burrs can damage the insulation.
Regards, Joerg
I would also point out that "sharp" (IOW not well radiused) edges can
cause long-term problems with winding insulation, which is stressed
around a tight corner. The inside edge insulation gets squished up, and
the outer edge gets thinned out. Add heat + time, and creep may well result.
I had a hilarious argument with a so-called mechanical engineer about
this once. He reckoned that a 2.8mm dia. O-ring, bent 90 degrees around
a 1mm radius, maintains its shape. I reckoned he was an idiot. I was
right, water poured in at the edges. Of course he did have a 2.8mm
channel for the O-ring at the corner (cf 2.5mm elsewhere). The O-ring
thinned out by about 0.3mm. Even showing him the o-ring under a
microscope wasnt enough to convince him. It convinced me never to use
him again.
His fix was to use a 3mm O-ring, which made the unit impossible to
assemble. His fix for that was to use vaseline, which then destroyed
(completely! looked like a sledge hammer had been used) $300,000 worth
of polycarbonate-based plastic enclosures, which *he* had designed and
made. His choice of material, too. It took about 3 months for the scale
of the problem to become apparent, in the field. At that stage, lawyers
were called (and I learned a lot about the interaction of plastics and
other goodies)
Cheers
Terry