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<p><font face="Candara">Volker ...</font></p>
<p><font face="Candara">Sorry but I can't agree with your comments.</font></p>
<p><font face="Candara">1. Capacitance will tend to show as a lower
insulation resistance while it charges, hence why longer cables
get a time.</font></p>
<p><font face="Candara">There is also the reversal to ensure that
the dielectric hasn't polarised and giving a false reading.</font></p>
<p><font face="Candara"><br>
</font></p>
<p><font face="Candara">My comment about comms cables was more that
"just because you can, doesn't mean it's a good idea" as we are
now finding out.<br>
</font></p>
<p><br>
</p>
<p><font face="Candara"><br>
</font></p>
<p><font face="Candara">2. I've had something checked for Electrical
safety and they certainly didn't do those tests, and I can't see
why they would deliberately destroy and exceed every component
rating to prove ???</font></p>
<p><font face="Candara">I'm not sure where the conductive path is
when you ".. wrap the whole thing in tinfoil and earth that and
put 1kv into all the connections".</font></p>
<p><font face="Candara"><br>
</font></p>
<font face="Candara">I can't download a copy of EN60950 (which has
been superceeded) but it a very general standard for a range of
equipment and it did say 'not all tests are applicable' in the
little info I could find.<br>
<br>
For those wanting to verify the requirements and methods, you can
download a copy of NZ/AS 3760 here.<br>
<a class="moz-txt-link-freetext" href="https://www.currenttags.nz/files/Electrical_Safety_AS_3760-2003.pdf">https://www.currenttags.nz/files/Electrical_Safety_AS_3760-2003.pdf</a><br>
<br>
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<br>
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</font>
<div class="moz-cite-prefix">On 26/01/21 22:22, Volker Kuhlmann
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:20210126092240.GA16462@top.geek.nz">
<blockquote type="cite">
<pre wrap="">That is generally used for electrical cables and is to ensure the cable
capacitance isn't influencing the measurement.
</pre>
</blockquote>
<pre wrap="">
That capacitance would show up as the increasing resistance Synco
mentioned. My understanding is that insulators also have a time
component for breakdowns, like a damn holding for 5s and collapsing
after 50s. The capacitance should be charged well before those 60s.
If you give your appliance, telephone or consumer goods designs to a
test lab to test for EN60950 (electrical safety), they wrap the whole
thing in tin foil, earth that, and put 1kV into all the connector
conductors (power, data, ...) for 60s. Voltage breakdown, significant
current flow, bang = FAIL. Test is potentially destructive. If there is
a supply energy limit, I'd expect it to be significantly higher than of
those insulation testers mentioned and in the don't f... touch this
range.
Volker
</pre>
</blockquote>
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