I posted this response earlier, but I managed to leave off the subject heading.
On 12/31/2010, Ryan Jayasinghe wrote:
I have to give our design engineer the protection level requirements
for two
interfaces that will terminate outside plant wiring at the Customer Premise,
which are T1 (RJ48) and DS3 (BNC) connectors.
These will be pluggable interfaces in 1U metal chassis with AC and DC
power,
and a Protective Earth ground connection. The DC is DC-Isolated.
The product needs to meet GR-1089 (Type 3 and 5) and other requirements
such
as, TIA968, ITU K.20/21 and UL60950. Although I have read through all these
Standards as well as other White Papers I do not have a clear understanding of
what level of voltage protection and fusing component are needed.
I also don't have a clear understanding of the current limiting
features.
Are these requirements set by local ordinances?
...........Also GR-1089 4.10 Criteria for Equipment Interfacing with
Coaxial
Cable Ports state that "These criteria that interface with OSP cable are not
intended for conventional telecommunications services, such as DS3".
Does this mean that the DS3/BNC interface will NOT require any testing
to
Section 4?
I maybe missing a bigger part of this picture so any advise is greatly
appreciated.
Hi Ryan:
GR-1089 makes certain assumptions about the "typical" level of external
protection that is installed in various types of network interfaces. The
default requirements that your product has to meet are based on these
assumptions. There is room in GR-1089 for you to specify that your equipment
can only be used in conjunction with a specific external protector that is
provided by the user, but that is not generally a good approach unless your
equipment will be used in a very specific, limited application. The people
why are buying your equipment will probably object to having such a
restriction on the use of your product.
The best approach is classify your equipment interfaces according to the
Appendix B guidelines (as you have already started working on), and then
design your equipment to meet the applicable tests. When properly done,
designing T1 and DS3 interfaces for GR-1089 compliance usually creates very
little added complexity or cost. The key is to fully understand the specific
surges and overvoltages that will be applied, and how those tests will
interact with your interface circuit.
Regarding your question about DS3, the GR-1089 term "OSP cable" refers to
cables that run outside the equipment enclosure and are exposed to
environmental threats such as lightning and power cross. As I recall, the
maximum cable length for DS3 coax is quite short (six feet?), which makes it
unsuitable for use as an OSP cable. I think this is what the GR-1089
reference is noting.
Depending on how you are using the DS3 coax and where it is installed, it may
turn out to be a Type 4 port that is subject to fewer protection requirements.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
[email protected]
http://www.randolph-telecom.com <http://www.randolph-telecom.com/>
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
<[email protected]>
All emc-pstc postings are archived and searchable on the web at
http://product-compliance.oc.ieee.org/
Graphics (in well-used formats), large files, etc. can be posted to that URL.
Website: http://www.ieee-pses.org/
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <[email protected]>
Mike Cantwell <[email protected]>
For policy questions, send mail to:
Jim Bacher <[email protected]>
David Heald <[email protected]>
