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Eric, I agree that Pollution Degree (PD) and Ingress Protection (IP) appear to be very similar. However, it is my understanding that these two are not the same. IP is protection from ingress of contaminants in the macro-environment and PD is a micro-environment parameter for calculation of dimensioning for insulation. Certainly IP is able to influence PD, for example, humidity influences conductivity of pollution but it is not strictly pollution by itself. I believe it is possible to claim PD2 or better for outdoor enclosures, under certain conditions. Ultimately, all buildings with electrical equipment installed are enclosures of one sort or another and we routinely see buildings achieve PD2 or even PD1 in a PD4 environment. I would think a gasketed enclosure with no negative pressure differential would work fine. In addition, I don't believe it is necessary to hermetically seal the enclosure. Directly correlating PD to IP class or NEMA enclosures is another problem. Although it seems reasonable, I'm not sure that I would know how to begin. Whereas IP has a progressive numerical relationship from one level to the next, PD describes different types of pollution at each level (e.g. conductive vs. non-conductive). Eventually, it is the manufacturer of the product who declares the PD of the environment and the IP of the product. This, in turn, drives the choice of insulating materials, dimensioning of spacings and the possible need for coatings on PWBs. I should mention that I once had an experience where I thought I had a sealed enclosure and successfully reduced PD3 down to PD2. What I forgot was the pressure differential from interior to exterior of the enclosure. The equipment had an open cable conduit routed to another part of the factory. The facility main heating system actually caused a small pressure differential from one end of the building to another and the conduit behaved much like an air supply, a dirty air supply. I ended up with quite a bit of pollution inside the enclosure. An excellent reading resource is: "The physical fundamentals of low-voltage insulation co-ordination" / Klaus Stimper - Berlin; Offenbach: vde-verlag. 1991. This book is not longer available in English and I contacted Mr. Stimper about this a couple years ago. If you can find a copy, this book explains much of the background to IEC 664 and IEC 664A. I refer to it quite often. If there is enough interest, possibly VDE-Verlag can be convinced to publish a new English version. Regards, -doug Douglas E. Powell, Staff Engineer Corporate Compliance Dept. Advanced Energy Industries, Inc. Fort Collins, CO 80525 USA From: owner-emc-p...@listserv.ieee.org [mailto:owner-emc-p...@listserv.ieee.org] On Behalf Of intert...@safety.demon.co.uk Sent: Tuesday, June 01, 2004 12:51 PM To: emc-p...@majordomo.ieee.org Subject: Pollution Degrees EN60950 - are others struggling too ! http://www.ieee-pses.org/symposium http://www.emc2004.org/ Only two replies to this one last week - thank you guys - good supportive information. Can I entice any further responses ? I have IT equipment certified to EN60950 - Pollution Degree 2. The designer swears blind that his out-door cabinet can meet the requirements of Pollution Degree 2 - IT IS VERY DOUBTFUL. Do any environmental test labs in the UK test to EN60950 - Pollution Degree 2 ? I believe they only test IP ratings - that is why I need to correlate Pollution Degree 2 to an IP rating. While we are at it : Would anyone venture to correlate Pollution Degree 1 & 3 to IP ratings ? Eric ericm...@intertest.co.uk IEng, IIE, SEE, IIRSM INTERTest Systems UK the trading name of the test laboratory of E M Consulting Ltd Safety - Consultancy, evaluation and Int Certification This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. IEEE PSES Main Website: http://www.ieee-pses.org/ To post a message send your e-mail to emc-p...@ieee.org Instructions for use of the list server: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. IEEE PSES Main Website: http://www.ieee-pses.org/ To post a message send your e-mail to emc-p...@ieee.org Instructions for use of the list server: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstcTitle: RE: Pollution Degrees EN60950 - are others struggling too !
http://www.ieee-pses.org/symposium
http://www.emc2004.org/
--------------------------------------------------
Eric,
I agree that Pollution Degree (PD) and Ingress Protection (IP) appear to
be very similar. However, it is my understanding that these two are not
the same. IP is protection from ingress of contaminants in the
macro-environment and PD is a micro-environment parameter for
calculation of dimensioning for insulation. Certainly IP is able to
influence PD, for example, humidity influences conductivity of pollution
but it is not strictly pollution by itself.
I believe it is possible to claim PD2 or better for outdoor enclosures,
under certain conditions. Ultimately, all buildings with electrical
equipment installed are enclosures of one sort or another and we
routinely see buildings achieve PD2 or even PD1 in a PD4 environment. I
would think a gasketed enclosure with no negative pressure differential
would work fine. In addition, I don't believe it is necessary to
hermetically seal the enclosure.
Directly correlating PD to IP class or NEMA enclosures is another
problem. Although it seems reasonable, I'm not sure that I would know
how to begin. Whereas IP has a progressive numerical relationship from
one level to the next, PD describes different types of pollution at each
level (e.g. conductive vs. non-conductive). Eventually, it is the
manufacturer of the product who declares the PD of the environment and
the IP of the product. This, in turn, drives the choice of insulating
materials, dimensioning of spacings and the possible need for coatings
on PWBs.
I should mention that I once had an experience where I thought I had a
sealed enclosure and successfully reduced PD3 down to PD2. What I
forgot was the pressure differential from interior to exterior of the
enclosure. The equipment had an open cable conduit routed to another
part of the factory. The facility main heating system actually caused a
small pressure differential from one end of the building to another and
the conduit behaved much like an air supply, a dirty air supply. I
ended up with quite a bit of pollution inside the enclosure.
An excellent reading resource is: "The physical fundamentals of
low-voltage insulation co-ordination" / Klaus Stimper - Berlin;
Offenbach: vde-verlag. 1991. This book is not longer available in
English and I contacted Mr. Stimper about this a couple years ago. If
you can find a copy, this book explains much of the background to IEC
664 and IEC 664A. I refer to it quite often. If there is enough
interest, possibly VDE-Verlag can be convinced to publish a new English
version.
Regards,
-doug
-------------------------------------
Douglas E. Powell, Staff Engineer
Corporate Compliance Dept.
Advanced Energy Industries, Inc.
Fort Collins, CO 80525 USA
-----Original Message-----
From: owner-emc-p...@listserv.ieee.org
[mailto:owner-emc-p...@listserv.ieee.org] On Behalf Of
intert...@safety.demon.co.uk
Sent: Tuesday, June 01, 2004 12:51 PM
To: emc-p...@majordomo.ieee.org
Subject: Pollution Degrees EN60950 - are others struggling too !
http://www.ieee-pses.org/symposium
http://www.emc2004.org/
--------------------------------------------------
Only two replies to this one last week -
thank you guys - good supportive information.
Can I entice any further responses ?
I have IT equipment certified to EN60950 - Pollution Degree 2. The
designer swears blind that his out-door cabinet can meet the
requirements of Pollution Degree 2 - IT IS VERY DOUBTFUL.
Do any environmental test labs in the UK test to
EN60950 - Pollution Degree 2 ?
I believe they only test IP ratings - that is why I need to correlate
Pollution Degree 2 to an IP rating.
While we are at it :
Would anyone venture to correlate Pollution Degree 1 & 3
to IP ratings ?
Eric
ericm...@intertest.co.uk IEng, IIE, SEE, IIRSM
INTERTest Systems UK
the trading name of the test laboratory
of E M Consulting Ltd
Safety - Consultancy, evaluation and Int Certification
-------------------------------------------
This message is from the IEEE Product Safety Engineering Society
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For help, send mail to the list administrators:
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For policy questions, send mail to:
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All emc-pstc postings are archived and searchable on the web at:
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-------------------------------------------
This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list.
IEEE PSES Main Website: http://www.ieee-pses.org/
To post a message send your e-mail to emc-p...@ieee.org
Instructions for use of the list server:
http://listserv.ieee.org/listserv/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Ron Pickard: emc-p...@hypercom.com
Dave Heald: emc_p...@symbol.com
For policy questions, send mail to:
Richard Nute: ri...@ieee.org
Jim Bacher: j.bac...@ieee.org
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
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