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Registered Member #1936
Joined: Sun Jan 25 2009, 11:34AM
Location: USA
Posts: 17
Harry wrote ...
(I am not suggesting anyone copy the exacting methods of the Park Resistor , but for those who don't yet know of this famous high voltage device, it may be good to know that such a simple passive component is the gold standard of high voltage measurement throughout the United States)
Interesting. And I thought the $630 peanut butter was the oddest thing at the NIST. Makes sense though. I mean a standard is just a value or quantity that someone else makes everyone else use. As long as everyone else's "blarq" is the same as the original "blarq" the "blarq" is a unit of measure.
Link to $630 peanut butter for the un-initiated:
Link to the Park Resistor:
Good find!
Now to go add the Park Resistor to Wikipedia... Finally found something noteworthy that's not already in it.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
DerSchwamm wrote ...
Link to the Park Resistor:
Good find!
Now to go add the Park Resistor to Wikipedia... Finally found something noteworthy that's not already in it.
Hi Sponge!
The original story of the invention by J.H. Park himself - with a great picture - is here:
Park J.H.Special Shielded Resistor for High-Voltage D-C Measurements Journal of Research of the National Bureau of Standards—C. Engineering and Instrumentation. Vol. 66C, No. 1, January - March 1962.
Registered Member #1911
Joined: Mon Jan 05 2009, 06:30PM
Location: Salem, Oregon, USA
Posts: 165
You can use paraffin or candle wax. What I've heard of others doing is encasing their transformers in paraffin or beeswax because it melts pretty easily, then placing a layer of candle wax on top because it is harder to melt and leaves a nicer finish.
Registered Member #311
Joined: Sun Mar 12 2006, 08:28PM
Location:
Posts: 253
The thing to remember about corona is that it is the ionisation of air. So the most effective way to prevent it is to stop the air getting to the conductive parts in the first place - conformal coating, wax, potting etc. are all good, provided their dielectric strength is sufficient to withstand the voltage. Vacuuming whilst drying can also help a lot, especially with thicker encapsulants like epoxy etc. - an air bubble can contain ionised air, which then damages the coating, leading to tracking and breakdown. Sharp points should still be avoided as these increase the stress on the insulating coating.
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Ways to stop corona..List please?
, but for those who don't yet know of this famous high voltage device, it may be good to know that such a simple passive component is the gold standard of high voltage measurement throughout the United States) 
