OHVM HV Breakdown Test, Plastic Use Warning

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Sharpe by way of Terry Fritz <teslalist-at-qwest-dot-net>" <sccr4us-at-erols-dot-com>

All
I ran a full power HV breakdown test of my OHVM high voltage
divider.  It is basically a 8.5" x 10" PCB with TVSS and load
resistors integrally mounted, suspended upside down on a 3/8"
Lexan top.  The entire assembly sits inside an 'O'-ringed
10" wide x 12" long x 2" thick UHMW PE enclosure that 1-1/2"
of material has been milled out.  Top is held in place using (38)
1/4"-20 x 2" long nylon pan head screws on top and hex nuts in
counter bored holes from bottom.  Enclosure was filled using
60 oz (3 bottles) of Wal-Mart brand baby oil.

Unit successfully operated for 5 minutes at 24kV (~35kV peak).
I then ramped voltage by rewiring PT's primaries in series to
parallel.  I then ramped voltage up to 40kV rms (~56kV peak;
8.08V rms out).  No overheating, no corona in a darkened room,
and no partial discharge picked up on AM radio  (  :^)))  ).
Now its time for final assembly and end to end calibration.

Although slightly off this topic, a piece of advice for those of
you out there using Polycarbonate (Lexan) for components or
assemblies.  DO NOT allow fast evaporation liquids (canned
air, defluxing compounds, fast evaporation aromatics) to
contact the Lexan.  My first cover plate cracked between
3 holes when I used flux remover on OHVM divider board!
It appears to be a thermal shock phenomenon, that will cause
cracks to propagate through the Lexan; IDK if this problem
is possible with other plastics commonly used (ABS, Plexiglas
[Acrylic/Perspex]).  Surprised the hel.. out of me, and set
my completion date back a week...  :^C

Up loaded two new files showing test setup for 2.4kV and
the oil divider final subassembly. Files are at:

http://hot-streamer-dot-com/dave

    OHVM 2_4kV HV divider test setup.jpg
2.4kV powered setup to determine Rdivide ratio

    OHVM Oil Jacket Rdivider.jpg
Divider nework assembly completed (including oil), ready for use.

Corrected error seen at 60Hz <<1%.

Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA. USA