Re: Effect of Paint on Polymeric Enclosure Materials
Hi Peter: A manufacturer has an IEC 950 type equipment with a polymeric enclosure meeting the fire enclosure requirements, in this case, enclosure is flame rated min. 94V-1. Assuming he now painted the enclosure to give it a better look, will this have an effect on the original flame rating? I would assume that the paint/enclosure combination could degrade the flammability rating. I believe the answer is that the change to the flame rating will be a function of the paint itself, i.e., there is no general answer. The paint may improve the rating, it may not affect the rating, or it may degrade the rating. I suggest that you perform an A-B comparison test. Cut 1/2-inch by 5 inch bars from the same part of two enclosures, one with paint and one without paint. Then perform the vertical burning test per UL 94. Since you are performing a comparison test, it is not necessary to have the precise UL 94 test set-up. The only important test criteria are: the bars be held in a vertical position; the flame is the same for both painted and unpainted tests. For the purposes of such testing, you can hold the bars with pliers above a candle flame. The bar is removed from the flame after 10 seconds, and the time of flaming is recorded. Degradation for V-1 to V-2 only requires that the bar drop flaming drops. All other burn criteria remain the same. Upgrading from V-1 to V-0 requires very much less burning time, 30 seconds to 10 seconds. The paint is heat-sunk by the plastic. Assuming a thin coat of paint, the temperature of the paint is the same temperature as the surface of the plastic. Furthermore, the paint prevents oxygen from reaching the surface of the plastic. The plastic cannot burn until the paint has burned or is otherwise damaged to allow oxygen to the surface of the plastic. If the paint burns at a higher temperature than the plastic, then the paint will retard the rate of burning, and the sample could go from V-1 to V-0. If the paint burns at a lower temperature than the plastic, then the paint will quickly burn off the surface, and the plastic will burn as if there is no paint. Because the paint is thin compared to the plastic, the paint will not contribute much thermal energy to the plastic, and should not increase the duration of burning by a large amount, i.e., enough to exceed the allowed 30-second burn time for V-1. Also, I don't believe the paint will contribute to the plastic dropping flaming drops, which is the difference between V-1 and V-2. In my opinion, a thin coat of paint should not degrade the flame rating, and may improve the flame rating. If the paint is a thick coat, then the burning characteristics of the paint will have a much larger effect and will not fit this analysis. If the paint is only on one side of the plastic, then I believe the plastic will burn normally on the unpainted side, and the paint will have no effect on the flame test (althought it might have an effect on the end-product). Remember that the UL 94 test is done with bars; the edges of the bars will not have paint. The flame is applied to the bottom edge of the bar, to the unpainted plastic. I believe that this point of ignition and the subsequent burning will overcome the effects of the paint where the paint ignition temperature is less than that of the plastic. Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: EFFECT
Peter, Think about why the standards define normal environment (temperature, humidity, airpressure,etc.)conditions when performing a test. Those environment parameters will cause the frequency to shift, cause the amplitude to change, etc..A simple example, when the emperature increases, the holes / gaps of the cover become larger, cut-off frequency becomes smaller, shielding effectiveness is reduced, your reading may become higher. If you had tested Radio Equipment against FCC Part 101, or ETSI 300-XXX, you would find both frequency and output power need to be tested by varying the environmental conditions. That's why we have to record all of those parameters during whatsever tests. Hope it helps, Leslie --- PETER PHILLIPS peter.phill...@mira.co.uk wrote: Dear group, Has anybody heard about the term EFFECT relating to EMC and environmental testing combined. I am looking for any information on the topic, also any views that people may have regarding the change in EMC performance due to adverse environmental conditions Looking forward to your comments Peter Peter Phillips MIRA (Motor Industry Research Association) Tel:++44 (0)1203 355576 Fax:++44 (0)1203 355486 e-mail peter.phill...@mira.co.uk - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: EFFECT
Hi Peter ... At 02:41 PM 6/28/99 +0100, PETER PHILLIPS wrote: Dear group, Has anybody heard about the term EFFECT relating to EMC and environmental testing combined. No. I believe there's an aircraft test that's titled something like Magnetic Effects. But I have no idea what that test entails and I don't know if it's a combination type test. Someone out there must know. I once suggested the idea of going into an environmental with a piece of equipment to do ESD testing at various RHs for a Bellcore style testing. That went over like a lead balloon. I'm sort a glad of that since the discussion went onto temperature testing with ESD at various temp levels below freezing. For some strange reason, standing in a 6x6x6 ft room in tropical conditions one minute then arctic conditions the next while recording something like 200 data points at various ESD levels just wasn't all that appealing. But if I thought of it, I'm sure someone else has ... I am looking for any information on the topic, also any views that people may have regarding the change in EMC performance due to adverse environmental conditions I had a PLL circuit giving me a bear of a time until I came back the next day after leaving at the site in below freezing temps. When it was turned on the next day, no PLL. Turned out the xtal froze up. But, it wasn't below the mfr's specs. Seems as though the mechanical impedance of the xtal was so high from low temps it wouldn't self start. That in turn started a routine test of prototype circuits using xtals in PLLs to be put into an environmental chamber at low temps. Looking forward to your comments Besides speculating with Paschen's Law, I'd also like to hear any testing that combines ESD + altitude. Also, ESD + humidity. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: EFFECT
Hello Peter: There is no combined EMC and environmental test that I am awared of. However, I suppose, you can perform some kind of Stress Screening or temperature shock test (i.e. Mil-Std-810). This will prematurely age you equipment/product prior to performing EMC so that you can perform EMC test on a aged products. Best Regards, Nezam Najafi Sr. Compliance Engineer Madge Networks, New Jersey -Original Message- From: PETER PHILLIPS [mailto:peter.phill...@mira.co.uk] Sent: Monday, June 28, 1999 9:41 AM To: Emc-Pstc (E-mail) Subject: EFFECT Dear group, Has anybody heard about the term EFFECT relating to EMC and environmental testing combined. I am looking for any information on the topic, also any views that people may have regarding the change in EMC performance due to adverse environmental conditions Looking forward to your comments Peter Peter Phillips MIRA (Motor Industry Research Association) Tel:++44 (0)1203 355576 Fax:++44 (0)1203 355486 e-mail peter.phill...@mira.co.uk - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: EFFECT
I agree with the substance of Ed's comment. In my experience the more usual terminology is EME = electromagnetic environment, while E3 (E-cubed) = electromagnetic environmental effects. Neither of these terms relates directly to the adverse effect on rf or EMC performance due to other environmental conditions. -Original Message- From: ed.pr...@cubic.com [SMTP:ed.pr...@cubic.com] Sent: Monday, June 28, 1999 11:43 AM To: EMC-PSTC; PETER PHILLIPS Subject: Re: EFFECT Peter: Electromagnetic Effects (EME) is a bit more comprehensive a concept than Electromagnetic Compatibility (EMC). There are many things that you can do with electromagnetic energy that are not necessarily related to compatibility. RF techniques can be used to investigate or change physical properties, protect friendly forces, confuse hostile forces, deny use of assets, eavesdrop; well, lot's more. I would say that EMC is a subset of EME. Regards, Ed From: PETER PHILLIPS peter.phill...@mira.co.uk Subject: EFFECT Date: Mon, 28 Jun 1999 14:41:12 +0100 To: Emc-Pstc (E-mail) emc-p...@ieee.org Dear group, Has anybody heard about the term EFFECT relating to EMC and environmental testing combined. I am looking for any information on the topic, also any views that people may have regarding the change in EMC performance due to adverse environmental conditions Looking forward to your comments Peter Peter Phillips MIRA (Motor Industry Research Association) Tel:++44 (0)1203 355576 Fax:++44 (0)1203 355486 e-mail peter.phill...@mira.co.uk - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). ---End of Original Message- -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 Date: 06/28/1999 Time: 08:42:51 Military Avionics EMC Services Our Specialty Also Environmental / Metrology / Reliability -- - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: EFFECT
Peter: Electromagnetic Effects (EME) is a bit more comprehensive a concept than Electromagnetic Compatibility (EMC). There are many things that you can do with electromagnetic energy that are not necessarily related to compatibility. RF techniques can be used to investigate or change physical properties, protect friendly forces, confuse hostile forces, deny use of assets, eavesdrop; well, lot's more. I would say that EMC is a subset of EME. Regards, Ed From: PETER PHILLIPS peter.phill...@mira.co.uk Subject: EFFECT Date: Mon, 28 Jun 1999 14:41:12 +0100 To: Emc-Pstc (E-mail) emc-p...@ieee.org Dear group, Has anybody heard about the term EFFECT relating to EMC and environmental testing combined. I am looking for any information on the topic, also any views that people may have regarding the change in EMC performance due to adverse environmental conditions Looking forward to your comments Peter Peter Phillips MIRA (Motor Industry Research Association) Tel:++44 (0)1203 355576 Fax:++44 (0)1203 355486 e-mail peter.phill...@mira.co.uk - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). ---End of Original Message- -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 06/28/1999 Time: 08:42:51 Military Avionics EMC Services Our Specialty Also Environmental / Metrology / Reliability -- - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
