From: "bob" <[email protected]> Subject: Re: UL 1950 3rd, and IEC 950
The question of isolation between circuits TNV1, TNV2, TNV3 and SLEV, can be addressed from IEC-950 and Bell core specs requirements point of view. IEC-950: As most of you already may know. The objective of this requirement is that when telecom equipment in this case is operated it must not cause electric shock to the personnel and or fire. Bell Core: The objective: The Objective given above for iEC-950 plus network reliability under abnormal conditions due to nature etc.. FCC-68/IC: The requirments of this standard seams to be a subset of BELL CORE requirements, the orignal intent was to protect the BELL CORE's network from harm by Joe's devices connecting to the network. Recently FCC-68 has considered product reliabilty aspect as well, based upon complaints perhaps from the users/vendors etc. The electric with stand strength across 1" gap in a vacuum is 75KVpeak. Which translates to 75Vp/mil (in vacuum). The arcing can be affected by atmospheric pressure, humidity levels and other chemicals used in the manufactruring processes. I have seen 40 mils can with stand 1000Vrms reliably. When someone chooses to perform only high voltage surge tests and expects to inspect the arcing phenomon by visual inspection or visible arcing point of view. I must say that it looks like hit or mis type situation. The best way to identify the problem of arcing is that across given test points when surges are applied immediately after each specified number of surges apply 1000Vrms (current less than equal to 10 milli Arms) . I expect, one will be very sure of which type of surges have caused braekdown acroos test points!!! Your comments are always welcome with open mind. Thank you. http://www.microvolt.com -----Original Message----- From: Victor L. Boersma <[email protected]> To: INTERNET:[email protected] <[email protected]> List-Post: [email protected] Date: Wednesday, April 29, 1998 4:57 PM Subject: RE: UL 1950 3rd, and IEC 950 > Answers to questions like these are VERY important in trying fit telco > owned equipment into the IEC 950 based standards which were written from > the CPE perspective. IEC950 was written from a Data Processing equipment perspective. We than had to wangle telecom equipment in, sometimes not all that gracefully. That is not offered as an excuse, but may make more understandable what went on. Ciao, Vic
