Andrew,
Your comments are misplaced, "creepage" is not an IPC term nor
specified in their specs that I have seen/used. My understanding is that they
conveniently ignore it because it goes beyond the circuit board
design/fabrication.
Creepage is used by the other regulatory bodies (UL/CSA/EU/TUV/etc.).
If what you state were true then there would be only one leakage spacing spec,
but there are are (at least) two and they are typically significantly different
spacings/values. Therefore "leakage" is not "LEAKAGE" (generic & all
encompassing), is not "creepage".
I was just trying to point out a couple of issues that can catch those
less knowledgeable. I don't claim significant expertise here but I did do a
brief stint at an internationally reknown power supply/converter company and
both spacings are different and required by various safety compliance
regulators. By the way, those specified spacings already have an engineering
margin in them and don't require further margins being added again.
Sincerely,
Brad Velander
Senior PCB Designer
Northern Airborne Technology
#14 - 1925 Kirschner Road,
Kelowna, BC, V1Y 4N7.
tel (250) 763-2232 ext. 225
fax (250) 762-3374
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Wednesday, December 13, 2006 2:11 PM
To: [email protected]
Subject: Re: [PEDA] 500V power supply
Oh, come on...Electrical leakage is leakage Brad. Creepage is a "cute"
term meant to apply specifically to surface leakage, but it's all
leakage, as in electrical current flowing unexpectedly through a
dielectric medium. (call it over if you like, it's still "thru" to my
physics eye.) That's one of the novel things that the IPC brings to the
table. Redefinition of basic physics into terms that can suit the
purposes of obsfucation...and of course profit by intellectual ownership
of originally US-citizen-owned information.
For instance, when I designed an instrument for KLM a couple years ago
to (amongst other things) measure LEAKAGE from pin to pin on a
connector, the mode of transport under consideration was not leakage
across the air gap, but through the dielectric separating the contacts.
It's my policy to leave the cute to the IPC, Altium's marketing
Goo-Roos, and the cabal of "shhhhh...don't tell anyone its just water".
And yes, DC or AC, the critical value is the peak value. All AC is DC if
time passes slowly enough, and most DC is AC if you speed the clock a
bit. Peak values Carlos. That means not only what you expect, but what
might be. (Hence the engineering margins I spoke of earlier)
Regards,
aj
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