Hi Brian:
In my original response to Gary, I mentioned a booklet by Klaus Stimper. Mr. Stimper includes a table which defines micro-environment categories in terms of 1) percent relative humidity 2) salt deposition in gm/sq m 3) condensation 4) precipitation (rain) These four parameters "quantify" the pollution degrees. IEC 60664-1 "describes" the four degrees of pollution. You are correct that these parameters apply to the micro-environment of the specific clearances and creepage distances in the equipment. Indeed, the micro-environment may be different in different areas of the equipment. Interestingly, 664 states that dimensions for creepage distance cannot be specified for pollution degree 4! :-) Best regards, Rich > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Brian O'Connell > Sent: Tuesday, November 13, 2007 4:39 PM > To: '[email protected]' > Subject: RE: Pollution Degrees > > > Someone please immediately provide feedback if I am not > correct, but the answer to the question "In which document do > they describe/quantify this parameter?" seems to be NONE. I > have never seen this quantified, and have never heard an > agency engineer describe the properties of 'conductive > pollution', other than the di-electric breakdown level is decreased. > > There are some DoD docs where you can use some imagination > and deduce some of these parameters (MIL-STD-202, > MIL-STD-210, MIL-STD-810) and/or test methods. Perhaps the > best approach would be to 'work backwards' from the test > materials used to determine the CTI, which is part of the > construction data required to establish the requirements for > an enclosure. > > Another idea. Perhaps it is intentional to not quantify. As > pollution degree refers to the 'micro-climate', it is > dependent on the construction materials in the product. > Liquid or solid precipitates that may or may not be > conductive will have different effects on the material that > it condenses or falls on, depending on the PLC/CTI/IP ratings. > > luck, > Brian > > -----Original Message----- > From: [email protected] [mailto:[email protected]]On Behalf > Of [email protected] > Sent: Tuesday, November 13, 2007 3:45 PM > To: 'Gary Tornquist' > Cc: '[email protected]' > Subject: RE: Pollution Degrees > > Hi Gary: > > In IEC 60664-1, 2nd edition: > > 3.1.1: Defines pollution > > 3.1.3: Defines pollution degree > > 4.6.2: Degrees of pollution in the micro-environment > (describes the 4 degrees) > > In IEC 60664-1, 1.1, 1.2 editions: > > 1.3.11: Defines pollution > > 1.3.13: Defines pollution degree > > 2.5.1: Degrees of pollution in the micro-environment > (describes the 4 degrees) > > For a very good background treatise, see Klaus Stimper's > "The Physical Fundamentals of Low Voltage Insulation > Co-ordination," published by VDE. Section 5.1.3 describes > micro-environmental categories, the predecessor to pollution > degrees. (The English version of this booklet is out of > print.) > > If the 664 degree descriptions are not detailed enough for > your use, this booklet may describe the MEC's with the > detail that you are looking for. > > > Best regards, > Rich > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Gary Tornquist > Sent: Tuesday, November 13, 2007 11:00 AM > To: [email protected] > Subject: Pollution Degrees > > Compliance comrades - > We've dug through IEC 60664-1. Unfortunately, we did not > find what I was > looking for. I need your help once again. I am looking for > an official > expose on what the IEC precisely means by 'Pollution Degree'. > > In which document do they describe/quantify this parameter? > I understand that it generally means 'conductive dust and/or > moisture' and that it is > used to establish categories of creepage/clearance distances. > Well, what > the heck is 'conductive dust' and how do they quantify the > moisture levels? > > - our Reliability team is trying to quantify moisture/dust > exposure and > acceleration factors. Thanks for your help! > > Sincerely, > Gary Tornquist > > Director of Product Safety > Microsoft Corp. > 425-705-6099 > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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