Rich, >I have been told by one of our parts vendors that it is acceptable to >replace components between the different surge waveforms when doing >testing to sec.4 table 4-2 for first level lightning surges. Their >rationale is that the components are being stressed by the previous >tests. I am not convinced. I thought that each test sample should >withstand all of the surges. I don't want to take the vendor's word >alone because it is their parts that are failing.
>Any similar experiences or comments would be appreciated. Our interpretation is: a single card should survive (without component replacement) one subsection of the Level 1 tests, i.e., Test 3 (all positive and negative surges). When we go on to Test 4, we replace the card (or the components that were under stress). One important factor to consider -- heating of the components on the card from repeated lightning surges can cause failures, and you need to have sufficient delay time between each successive surge to ensure that this doesn't happen! (A minimum acceptable wait time between the Level 1 Test 3 surges might be one minute, for example, but it might need to be longer.) ________________________________________________________________ John Combs, Senior Project Engineer, ITS/TestMark Laboratories Email: [email protected] URL: http://www.testmark.com
