Mark and Cortland are both correct. For type A surges, the surges may damage the unit under test, but the unit cannot cause harm to the network after the surge, irregardless of of its operating condition. The most common “Harm” would be for the unit to go “off hook” in a permanent condition.
However, for a type B surge, the unit must not fail and continue to meet the requirements of the standard. This was originally a requirement in the original FCC Part 68 and was continued when I wrote (as editor) the TIA/EIA 968 document. John Shinn, Ph.D., P.E. Retired From: Dan Roman Sent: Friday, February 10, 2012 12:26 PM To: Mark Gandler ; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] TIA-968-A failure modes, notwithstanding... Hi Mark, I’ll reference TIA-968-B since it is the latest version of the standard. Under section 4.1 Environmental Simulation it states: Unpackaged approved terminal equipment and approved protective circuitry shall comply with all the criteria specified in this Standard, both prior to and after application of the mechanical and electrical stresses specified in this section. I think that pretty much says it all. So after all the mechanical shock and surges you cannot fail any of the other criteria. Hopefully if you are a piece of POTS equipment you fail on-hook which would simplify things somewhat. Failing off-hook could be tough to pass. If your equipment suffers catastrophic damage it needs to go down benignly with respect to the harms-based philosophy of the standard. Being non-operational cuts out a lot of testing. You can’t fail signal power level limitations if you are not outputting any signal for example. I have not thumbed through Part 68 lately but there may be more detail in there. A member of this list was one of the contributors to TIA-968-B and may chime in on this topic. Dan From: Mark Gandler [mailto:markgand...@hotmail.com] Sent: Friday, February 10, 2012 2:52 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] TIA-968-A failure modes, notwithstanding... Dan, "Your equipment may fail or be completely destroyed but it cannot take the network with it" this was my understanding as well (regardless of how poorly and senseless the standard written), but clearly it is not the sam understanding across the labs. Are where any guidance, f.a.q's or interpretations documents, articles published anywhere regarding this subject? "After the failure mode the applicable tests are repeated to make sure you product does not harm the network even if your product no longer operates." if the product is completely destroyed, would it be there nothing left to repeat the tests with? Mark -------------------------------------------------------------------------------- From: dan.ro...@dialogic.com To: markgand...@hotmail.com; EMC-PSTC@LISTSERV.IEEE.ORG Date: Fri, 10 Feb 2012 13:24:16 -0500 Subject: RE: [PSES] TIA-968-A failure modes, notwithstanding... Mark, Your equipment may fail or be completely destroyed but it cannot take the network with it. After the failure mode the applicable tests are repeated to make sure you product does not harm the network even if your product no longer operates. Dan From: Mark Gandler [mailto:markgand...@hotmail.com] Sent: Friday, February 10, 2012 12:48 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] TIA-968-A failure modes, notwithstanding... Group, trying to get to the bottom of the statement some of you saw many times over. Test is a power line surge, section 4.2.4 of TIA-968-A. This is a quote: "Failure Modes resulting from application of power line surge. Approved terminal equipment and approved protective circuitry shall comply with all the criteria in this standard, both prior to and after the application of the power line surge specified in 4.2.4, notwithstanding that this surge may result in partial or total destruction of the equipment under test" The use of the word "notwithstanding" is quite common throughout this standard. Been somewhat late English language acquirer, I looked it up in Merriam-Webster and easiest one for me was "in spite of". There are many different types of surge test pass/failure criteria's throughout 61000-4, GR1089 and others, from no traffic errors during the surge to it is ok if it falls apart, as long as it does not catch on fire and does not kill anyone. But these requirements are clearly defined in each standard. My question for TIA-968-A is: how can something be compliant with all the criteria in this standard "in spite of" been totally destructed? Does it mean it is ok if power adapter or power supply is dead or entire product, including voice port can be out? Test Lab did the 2.5kV test, power adapter stopped producing DC, but no arcing, burning or enclosure breach. Lab concluded the failure. I am probably missing something very obvious, so please be gentle. Thank you, Mark - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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