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Re: [TCML] Primary voltage considerations

On 10/12/18 11:32 AM, Yurtle Turtle via Tesla wrote:
  I'd think primary turn to turn surface tracking along the primary supports would occur.
     On Friday, October 12, 2018, 11:03:03 AM EDT, jimlux <jimlux@xxxxxxxxxxxxx> wrote:

Every few years, someone comes up with an inexpensive surplus X-ray
transformer (100kV kinds of voltages) - Life is really hard above around
30-40 kV - corona is a big issue, as is plain old breakdown.

Remember the rule of thumb is that you want 1" of clearance between
conductors per 10-15 kV - 30kV equipment tends be big and bulky.

Also consider the minimum conductor radius for no corona.  Breakdown
field in air is about 70kV/inch. The field at the surface of a
conducting sphere  V/radius, so a 1" diameter sphere at 35kV is right at
the breakdown - and a bit of surface roughness is all it takes.
Cylinders work pretty much like spheres -it's the smallest radius of
curvature that's important.

If your primary supports have long enough creepage distance, that won't happen. A rule of thumb is that distance along an insulating surface shuold be > 3 *free air spark distance.

So if your primary turns were 1/2" diameter tubing spaced 1" apart (center to center), your supports should be >1.5" along the support. So 1/2" height pegs on 1" centers would work.

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