Hi Benoit, I think that testing at voltage increments up to the standard limit (or beyond) is necessary. We too had several products that failed at 2 or 3 kV but never blinked at 8 kV. Testing to 8 kV only does meet the requirement of the standard, but if my customers keep asking for their money back, what good is the standard test? As for your hypothesis, I concur. Either one is possible. I never did go after figuring out why, just how to fix it. The solution would probably give a clue as to why, but it was long enough ago that I forget what it was.
Scott [email protected] -----Original Message----- From: [email protected] [SMTP:[email protected]] Sent: Thursday, August 19, 1999 1:07 PM To: [email protected]; [email protected] Subject: Re: EN50082-1:1997 & EN55024 Bonjour de Montreal, In another life, I was working for a EMC Test lab and we always used the step by step procedure which was in the ESD Standard. We tested using this procedure for years and we did encounter some products who failed at low level ESD but had no problem at higher levels. We wondered what to conclude and had some hypothesis. 1) may be the current path was different at higher level or 2) Lower levels might have a slightly longer rise time which tends to produce more energy in the lower part of the frequency spectrum where the EUT was more sensible. Since the products were not staying in our hands for long we never had a chance to investigate further. Comments ? At 10:07 19-08-99 -0400, Jim Hulbert wrote: >> >> >> >>Immunity test standards EN50082-1:1997 and EN 55024 call out the basic standards >>EN61000-4-2 and EN61000-4-5 for ESD and Surge. >> >>EN61000-4-2, Section 5 starts out "The preferential range of test levels for the >>ESD test is given in table 1. Testing shall also be satisfied at the >lower >>levels given in table 1." EN61000-4-5, Section 5 contains similar >wording. >>This is how we perform our compliance tests. We start at the lowest >test >>voltage levels from the respective tables and step up to the test levels called >>out in EN50082-1/ EN55024 (or higher, depending on our own in-house >product >>spec.) >> >>However, I have noticed that some test labs go straight to the levels called out >>in EN 50082-1/EN55024 and skip testing at the lower levels. I believe >this >>approach is incorrect because it does not conform to the requirements of >the >>basic standard and is simply not a complete test. As explained in EN61000-4-5, >>the non-linear current-voltage characteristics of the equipment under >test >>should be considered and the test voltage should therefore be increased >by steps >>up to the test level specified in the product standard or test plan. >The same >>rationale applies to ESD testing where current-voltage characteristics >are also >>non-linear. >> >>How do others approach these tests? Are we adding unnecessary test time >by >>starting at lower test voltages and stepping our way up or are the test >labs >>that go straight to the maximum test levels overlooking an important aspect of >>the testing? >> >>Jim Hulbert >>Senior Engineer-EMC >>Pitney Bowes -------------------------------------------------------------------------- Benoit Nadeau, ing. M.ing. (P.Eng., M.Eng) Gerant du Groupe Conformite (Conformity Group Manager) Matrox <http://www.matrox.com/> -------------------------------------------------------------------------- 1055, boul. St-Regis Dorval (Quebec) Canada H9P 2T4 Tel : (514) 822-6000 (x2475) FAX : (514) 822-6275 Internet : [email protected], <mailto:[email protected]> --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
