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Q on rating in volts per mil

The datasheet "spec" for a conformal coating is Dielectric Breakdown
Voltage, volts per ASTM, Meth. D149 = 6300V.
What the #$*&#(#$! is the actual rating in meaningful terms, volts
per mil?
 
L

legg

Jan 1, 1970
0
The datasheet "spec" for a conformal coating is Dielectric Breakdown
Voltage, volts per ASTM, Meth. D149 = 6300V.
What the #$*&#(#$! is the actual rating in meaningful terms, volts
per mil?

Type of conformal coating amd mfr?

RL
 
J

Jamie

Jan 1, 1970
0
The datasheet "spec" for a conformal coating is Dielectric Breakdown
Voltage, volts per ASTM, Meth. D149 = 6300V.
What the #$*&#(#$! is the actual rating in meaningful terms, volts per
mil?

Yes.


Jamie
 
Tim said:
Perhaps the manufacturer thinks that the meaningful rating is the
breakdown voltage that can be attained with the material when it is
properly applied.

Since that "proper application" would include some minimum thickness,
you're left with a voltage.

This, in turn, means that if you're intending to do some application that
_doesn't_ conform (as it were) to this minimum thickness, then you're
either (a) smarter than the manufacturer, or (b) dumber than the
manufacturer. It's always hard to tell which in these cases, because the
stuff has probably been in production since 1953, and all the folks that
actually knew did the math on it are dust.

You could try calling them up and asking how many coats you need to get a
withstanding voltage of whatever it is you're looking for. Sometimes
that'll prompt a response from someone who actually understands what's
going on and why, sometimes that just gets you shrugs (or worse, some
idiot sales man telling you what he thinks you want to hear so he can
sell you a case of the stuff).

Asking "could you recommend a competitor who's actually competent" will
piss them off, but might make you feel better.
At least the "specification" of Dielectric Withstand Voltage, volts
per MIL-I-46058C >1,500 is semi-access able in that the MIL spec
appears to specify 2mil coating (not eXplicitly clear,tho).
 
J

josephkk

Jan 1, 1970
0
Wow! The rating is "Yes." volts per mil. Thanks.

What part of that is a standard test unit for the past 40 years or more
don't you understand?

?-)
 
M

Martin Riddle

Jan 1, 1970
0
josephkk said:
What part of that is a standard test unit for the past 40 years or
more
don't you understand?

?-)

Some data sheet specify what thickness/distance was used in the D149
test.
I looks like common gaps are 0.010", and 0.050" . There is a difference
in results depending upon what gap is used.
It's not like D877 (for liquid dielectrics) which specifies a 0.100"
gap.

Cheers
 
Martin said:
I think D149 is done with a 0.100" gap.

<http://file.yizimg.com/305304/2012060809264490.pdf>

Cheers
Thank you very much for the copy.
Seems I was correct in saying the method would not be clearly
described and certainly not worth about $50.00 .
It is not clear what gap to use; the table of some tests that
included teflon at the top was nice !!VOLTS PER MIL!! but was incomplete
in that the D149 rating was sorely lacking (as points of reference).
What WAS clear is the "nagging" that the test specimen be dunked in
(transformer?) oil - and thus the test may become moot and/or yield
exaggerated results.
And, naturally, there was umpteen references to other "standards"
perhaps a hint to feed their infinite greed.
 
Martin said:
Some data sheet specify what thickness/distance was used in the D149
test.
I looks like common gaps are 0.010", and 0.050" . There is a difference
in results depending upon what gap is used.
It's not like D877 (for liquid dielectrics) which specifies a 0.100"
gap.

Cheers
...and of course, the gap used is studiously NOT mentioned!
 
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