Dan, I don't have access to EN61131-2, but I think you may of misinterpreted the standard. I believe that for double/reinforced insulation you will need two times the values in table for basic/supplementary insulation. Also, your product is Pollution degree 2 and not 1.
In general, there is a table for Basic/supplementary and different table for double/reinforced. But in some standards, they just say that the requirement for double/reinforced is twice the values in the table for basic/supplementary. This comes from the fact that double insulation is defined as basic PLUS supplementary. Therefore twice the value for a single basic/supplementary insulation. Pollution degree 1 is generally for potted or otherwise sealed components only. Normal products are pollution degree 2. Ned Devine Entela, Inc. Program Manager III Phone 616 248 9671 Fax 616 574 9752 e-mail [email protected] -----Original Message----- From: Dan Kinney (A) [mailto:[email protected]] Sent: Wednesday, December 20, 2000 12:03 PM To: Emc-Pstc (E-mail) Subject: creepage distances (EN61131-2) I know most of you don't use EN61131-2 (Safety for Programmable Controllers but I'm hoping the questions I have can be answered in general terms. And if anyone does have/use EN61131-2, I provide paragraph and table reference numbers. This is a very convoluted and confusing standard but I think we have looked at the creepage and clearance section long enough that we finally have it figured out. But before I commit to something, I'd like confirmation from this group. The standard provides definitions for basic, supplementary, double, and reinforced insulation (paragraph 1.4.26). It also provides a general rule of thumb, worst case creepage and clearance table for basic and supplementary insulation (paragraph 4.3 subparagraph 3) and its table). I interpret this to mean, if I use these very conservative creepages and clearances, I more than meet anything presented later in the standard. I also interpret this to mean the numbers within this table provide double insulation since the definition of double insulation is basic and supplementary insulation combined. The standard then provides several tables of creepage and clearances under very specific conditions that includes material types and pollution degrees. The one I'm most concerned with is the table for basic and supplementary creepage distances for printed wiring boards (Table 23). As with the previous paragraph, I interpret this to mean double insulation. The standard provides definitions for pollution degrees (paragraph 1.4.42). It says: Pollution degree 1: No pollution or only dry, non-conductive pollution occurs. The pollution has no influence. Pollution degree 2: Normally, only non-conductive pollution occurs. Occasionally, however, a temporary conductivity caused by condensation shall be expected. Pollution degree 3: Conductive pollution occurs, or dry, non-conductive pollution occurs which becomes conductive due to condensation which is expected. Our products, are intended for industrial or commercial environments and are specified to be mounted in a metal enclosure where pollutants are sealed out. Further our specifications clearly state our products work 5% to 95% non-condensing relative humidity. Thus I interpret the standard to mean our products should be evaluated under pollution degree 1. Lastly, paragraph 4.3.4 states creepage distances for reinforced insulation "shall be double the value for basic insulation". I interpret this paragraph to be non-applicable to the work we are doing since all the tables list basic and supplementary (double) creepage and clearance distances. It does not list basic creepage and clearances individually and thus I have nothing to double. But by using the values provided in the tables, I meet double insulation requirements. I apologize for this lengthy message. And I apologize if I haven't provided enough information to understand the situation. As I said, this is very confusing for we, the uninitiated. My questions center around my interpretations and can be distilled down to one question; have I interpreted each point above correctly? Any advice, general or specific, will be greatly appreciated. Happy Holidays all. Dan Kinney Horner APG ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
