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Re: [TCML] voltage
The definitive theoretical (and practical) discussion of VLF and LF
high voltage measurement techniques are clearly delineated in this
report by the US Navy. It was found by Bert Hickman and is a
_phenomenal_ reference.
http://www.dtic.mil/dtic/tr/fulltext/u2/a526052.pdf
The only caveats are it is based on arguably the worlds largest and
most powerful "push-pull" CW-VTTC (100kW) for insulator testing to
support VLF communications. The arc, spark, streamer breakdown
structure, measurement techniques, methodologies are all there for
the casual experimenter and/or professional to read and ponder.
There is nothing left to the imagination; in short an outstanding
reference. Voltages to 300kV are supported with this system, and
power requirements based on voltage needs are also discussed
in detail.
On Wed, Jan 25, 2012 at 3:19 PM, Jim Lux <jimlux@xxxxxxxxxxxxx> wrote:
> On 1/25/12 10:56 AM, Derek, Extreme Electronics wrote:
>>
>> Bob,
>> I agree will all you have said, apart from one item. I come from the UK
>> where inches and mm are interchanged regularly. (and with more success
>> than NASA) So I have always used the rule of thumb of 25Kv per inch as
>> this equates to a rule of thumb as 1Kv per mm.
>>
>> This Rule of thumb satisfies both measurement systems more easily I
>> think...
>>
>
>
> Except that it's wrong.
>
> In a needle gap, yes, 25-30kV/inch is reasonable, but it's highly dependent
> on the size of the needles and the distance.
>
> In a uniform field gap (or something very close.. sphere gap with spacing
> small compared to diameter of sphere), a 30kV/cm or 70kV/inch is a better
> thing.
>
> For a rule of thumb in construction, a clearance distance of 10-20kV/inch is
> good. 10 is pretty conservative, 20 is a bit bolder. It really depends on
> the radius of the conductors, of course.
>
>
> And, just to defend NASA, who pays my salary, it was the contractor who
> delivered data (in US Customary units) that did not conform to the published
> interface spec, which is in metric/SI, as are ALL deep space missions. It
> never occurred to anyone in the deep space navigation business that someone
> would do something like use pounds instead of newtons. You can fault the
> JPL folks for not catching the error, but in reality it was a "system
> failure" (i.e. a bunch of stuff aligned just wrong to result in the error).
>
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--
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA
Sharpe's Axiom of Murphy's Law
"Physics trumps opinion!"
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