[SI-LIST] Re: E1/T1/E3/T3 requirements
- From: David Heald <daveheald@xxxxxxxxxxxx>
- To: "Si-List (E-mail)" <si-list@xxxxxxxxxxxxx>
- Date: Thu, 17 Jan 2002 11:40:58 -0500
Wow, doesn't apply? Let us in on the secret, please....
I agree with Dave, Doug, Bill, and anyone else who says that you need
to meet FCC/UL/NEBS. If the cables for your T1/T3 lines exit the
building that they are present in (i.e. connect to the
"Telecommunications Network"), you will need to do significant lightning
and fault current testing. These tests are NOT FUN and can lead to
FIRES - I know, I used to work for a lab that did these tests (1089 &
UL) and I caught several products on fire (quite a exciting and dramatic
test - and smelly :o)). Hence, the need to do the tests before a LEC or
CLEC will purchase the product. Worst case surges: see GR-1089 4.5.6
through 4.5.8 and 4.5.11 through 4.5.15 (4 wire interfaces). Notice
also the NRTL Listing requirement in 4.5.3 (and Section 7).
If, however, your product is only for intrabuilding use, you will
still need to do the intrabuilding lightning surges in 1089 section
4.5.9.
Many other sections of GR1089 may apply to 4 wire interfaces that exit
the building (sections 5,6,and 8 among others) as well as other the
general requirements to your product in general.
The NRTL will have slightly less stringent tests (I believe - this is
my memory I'm referencing!).
As far as the FCC is concerned, if your product uses frequencies
greater than 9kHz, you have to comply with Part 15, and I strongly
believe (but with no personal experience) that Part 68 will apply
regardless. If your product is SOLELY for installation in a CO (no
other marketing at all - no office buildings, nothing), there are
technical exemptions from Part 15 (don't ask me where, but I proved it
at some point in my career I think), but GR-1089 parallels Part 15 up to
10GHz and goes lower (as low as 60Hz/10kHz depending). Part 68 should
still be required, though, as you are part of the telecommunications
network.
Back to your original question. I am unsure now of your actual trace
sizes or if this is related to the ground plane void question that was
raised recently, but the external connection OV&Surge requirements
require some significant isolation and current carrying capability.
Survivability tests ("The EUT must not be damaged and shall continue to
operate properly...") include 2500V, 500A, 2x10us(1.2x50 alt)
longitudinal surges, 1000V, 100A 10x1000us metallic surges, and 600V,
2.2A, 2 second power fault tests across tip and ring. So, if your
product does connect to external lines, you really need to pay attention
to your design. If it is purely intrabuilding, the requirements are
much simpler but FCC, NRTL, and
Seems like I forgot something, but it's almost lunch time and I've
spent far too much time on this already.
Call a good local test lab (& maybe even some not so local) that
specializes in NEBS and ask them - they should be able to give you a
quote of the necessary requirements (in the form of a quote) based on
your product specifications.
Good luck,
Dave Heald
"Milley, David" wrote:
>
> I have worked on various T1/E1 equipment for the past 5 years.
>
> If this is Central Office 'interoffice' equipment then it will have to meet
> Part 68 and UL 1950 and NEBS. If it's designated as 'intraoffice'
> equipment, then it will have to meet UL and NEBS in order to exist in a CO.
> The fact that it's a digital product makes no difference.
>
> Dave Milley
> Cetacean Networks
> Portsmouth, NH
>
> -----Original Message-----
> From: Bill Dempsey [mailto:BDempsey@xxxxxxxxxxxx]
> Sent: Tuesday, January 15, 2002 11:37 AM
> To: 'whizplayer@xxxxxxxxx'; Si-List (E-mail)
> Subject: [SI-LIST] Re: E1/T1/E3/T3 requirements
>
> 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 > >
> >
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