Wow, I know this is an SI list but since we're talking T1 on this thread I'll digress too... I am astonished that you're in a central office and yet you think you don't have to meet part 68 or UL. Cool. You state "since this is a digital product". In a previous private email I made mention of the fact that if you're intraoffice, and *not* talking to the outside world you're correct. Whenever you connect to the outside, T1 has to meet the part 68 req's (i.e. lightning, AC crossover). Just some thoughts. If you think you can get away without doing it you're the first. Congrats. Bill -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Bob Patel Sent: Tuesday, January 15, 2002 9:32 AM To: sandord@xxxxxxxxxxxxx; dmckean@xxxxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: E1/T1/E3/T3 requirements Hi! Thanks for the inputs I have received so far. I had a chat with our EMC engineer and he said that there will be no lightning test done on this product since this product will be at the Central office.Also this is a digital product and UL1950, FCCpart68 does not apply. I am just throwing out some reasons. Thanks Bob Sandor Daranyi wrote: Doug,Somehow 12mil became 12mm along the way! :-)I got out of telecommunications about 3 years ago and I don't have the rele=vant standards handy but working from memory...What I was referring to was that for example during a lightning strike ther=e can be very high currents conducted momentarily so even though I was s=aying overvoltage I was really thinking about the resulting high currents=which can damage the tracks. Wider PCB track - more current.The "short to power line" was not a reference to really high voltages just =something like a short to 240Vac, 120Vac or something similar. I guess t=he origin of that is (I'm guessing here) that telecommunications cables m=ay get close to power cables in real life and accidents can happen with s=ome of these cables cut. The standards define different levels of compli=ance and the operability of the equipment during and after these tests, (=e.g. data transmission errors under error condition but equipment recover=s; operator intervention required to restore functionality [like reset eq=uipment, change fuse] etc.) but I digress.The "short to power line" is probably not even relevant to the 12mil track =issue, anyway. If that sort of voltage is present transversally on the E=1/T1 lines than you'll need tricks other than the 12mil line width and if=exactly the same voltage is present on both tip and ring, than you are O=K anyway, unless the overvoltage protection circit is not correctly desi=gned.Regards,Sandor---Sandor DaranyiSenior Design EngineerArisctocrat Technologies Australia> -----Original Message-----> From: Doug McKean [mailto:dmckean@xxxxxxxxxxxxxxx]...> Depends upon what the voltage levels being used in the=20> applicable immunity and telephone standards for the product.=20>=20> For air discharge breakdown, as a "Rule of Thumb" I use =20> 1MV is 1 meter. 1KV is 1mm or 40 mils.=20> And 8Kv is ... well ... 8mm. And 12KV is, well, 12mm.=20>=20> Very rough estimates. Tip geometry can greatly affect this.=20> All follows Paschen actually for temp and pressure.=20> Telco environs can be rough. Especially the Bellcore standards. =20>=20> Hmmm ... 12KV sounds strangely similar to an average street=20> level power line voltage for a neighborhood which can run=20> anywhere from as low as 2.4KV to as high as 24KV with the=20> average about 12KV. Don't know. Just throwing out some=20> ideas which come to mind. Someone anticipating some=20> cross power condition like a telephone line crossing with=20> a power line? Interesting.=20>=20> For sensitive inputs, I've been known to carefully calculate=20> the separations required by the standards, then compare those=20> separations needed to pass the levels of testing, then multiply=20> the whole thing by 2 for a double safety factor if I can get away=20> with it. But that's me.=20>=20> Although 12mm sounds big, I'm not sure what levels the surge=20> and lightning tests might be. That would have to be checked.=20>=20> Personally, the more separation you can give me, the better.=20> Even if I don't need it.=20> -----Original Message-----> From: Sandor Daranyi [mailto:sandord@xxxxxxxxxxxxx]...>=20> Bob,>=20> If an overvoltage protection stage is present (for lightning=20> or short to power line) then it may make sense to "beef up"=20> the tracks - at least between the port connector and=20> protection device.>=20> I've seen/done E1 designs with 12mil tracks at the ports but=20> I've seen narrower (8mil) ones as well, in other designs. =20> Take your pick...>=20> > -----Original Message-----> > From: Bob Patel [mailto:whizplayer@xxxxxxxxx]> > Sent: Tuesday, 15 January 2002 11:13> > To: si_list> > Subject: [SI-LIST] E1/T1/E3/T3 requirements> >=20> >=20> > Hi! In our previous T1/T3 designs we have used line widths of=20> > 12mils for signals from the connector to the magnetic i.e.=20> > line side of the transformer. I asked why 12mil line width=20> > and my colleagues mentioned that this is to meet immunity=20> > requirements. I asked our EMC engineer and he did not see a > > reason for 12mil line width. So, it would be nice if somebody > > could shed light on this requirement. > > Thanks a lot in advance. > > Bob > > > ...------------------------------------------------------------------To unsubscribe from si-list:si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject fieldor to administer your membership from a web page, go to://www.freelists.org/webpage/si-listFor help:si-list-request@xxxxxxxxxxxxx with 'help' in the Subject fieldList archives are viewable at: //www.freelists.org/archives/si-listor at our remote archives:http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at:http://www.qsl.net/wb6tpu __________________________________________________ Do You Yahoo!? Send FREE video emails in Yahoo! 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