Hello All:
Just a quick followup on our discussion about the short circuit tests:
I just received my copy of Issue 3 of GR-1089, and when I went to replace
Issue 2 I found a 1-page bulletin from Telcordia, dated December 1999, tucked
in the front of my Issue 2 binder. The bulletin
All,
I agree with the concept that the short circuit is not always worst case. I
have seen many ITE power supplies shut down with a sc, but an output
overload lets the smoke out.
One problem with a trace opening is the reliability of that opening in a
safe manner. When a certified fuse blows,
Subject: RE: Short circuit tests in GR-1089
Last I heard, and please correct me if not, was that Verizon had
rejected the new standards much to the chagrin of the rest of the industry.
Gary
-Original Message-
From: j...@aol.com [mailto:j...@aol.com]
Sent: Wednesday
All -
In consideration of the proliferation of SMPS in electronic
equipment, it is not unrealistic to expect a simple
short-circuit might not meet the intent of GR-1089. While
many linear supplies will run indefinitely under sc, most
SMPS will go into hysteresis or shut down completely under a
...@majordomo.ieee.org] On Behalf Of Lou Aiken
Sent: Monday, November 25, 2002 10:38 PM
To: Ted Rook; j...@aol.com;
Subject: Re: Short circuit tests in GR-1089
I'd like to add that the product need not operate correctly after a
fault
condition causes a fuse to open, it must only remain safe - within
Joe,
It is quite common for local filtering consisting of an inductor followed by
a capacitor to be added in the logic-level supply rail following an on-board
DC:DC converter when powering sensitive ICs. Often there are many such
filters on each card and it is not feasible to fuse each of them
; emc-p...@majordomo.ieee.org
Subject: Re: Short circuit tests in GR-1089
Hello All:
Many thanks to all who responded to my question about this requirement. Many
of the responses were quite interesting and persuasive, even though some of
them were directly opposed. I think that the expanded
In a message dated 11/27/2002, Marko writes:
So what did you decide? Is a fuse blowing acceptable?
I'm sure others would be interested as well.
Hi Marko:
So you want me to go on the record so I can get flamed? OK, here goes:
The revised text in Issue 3 of GR-1089 (kindly posted to the
Hello All:
Many thanks to all who responded to my question about this requirement. Many
of the responses were quite interesting and persuasive, even though some of
them were directly opposed. I think that the expanded description in the new
third edition of GR-1089 helps resolve most of the
...@majordomo.ieee.org] On Behalf Of Lou Aiken
Sent: Monday, November 25, 2002 10:38 PM
To: Ted Rook; j...@aol.com;
Subject: Re: Short circuit tests in GR-1089
I'd like to add that the product need not operate correctly after a
fault
condition causes a fuse to open, it must only remain safe - within the
meaning
- Original Message -
From: Ted Rook t...@crestaudio.com
To: j...@aol.com; emc-p...@ieee.org
Sent: Monday, November 25, 2002 5:25 PM
Subject: Re: Short circuit tests in GR-1089
I'm not an expert on GR1089 but I think that your interpretation should
include careful consideration of what
I'm not an expert on GR1089 but I think that your interpretation should include
careful consideration of what constitutes damage.
The operation of a fuse or a circuit breaker is not damage.
That is normal operation.
What the specification is seeking to eliminate is overheating, explosion, loss
This was resolved a couple of NEBS conferences ago. All the main RBOCs
were present and they agreed that a fuse was a special case. The fuse
is designed to open, therefore operation of the fuse is normal and allowed.
This may be a semantic strech, but that's where the current NEBS
Joe,
I was going to suggest that you look into Issue 3 of GR-1089, but you have been
given the basics. I would suggest anyone who has to live with this standard,
get the new issue and spend a day or so to really look it over in detail.
There was a great deal of work put into clarifying
Joe,
Short-Circuit Tests
NOTE: The short-circuit tests that follow are intended to be performed only on
out-of-service equipment.
NOTE: Discrete equipment assemblies that have been listed by an NRTL to UL
60950[31] generally need not be subjected to the short circuit tests in Section
9.10.1
...@world.std.com
Subject: RE: Short circuit tests in GR-1089
Joe,
The short-circuit test is to simulate the most prevalent source of telecom
disruption: the back-hoe.
When a buried cable is inadvertently cut, the pairs could short together or
to the cable sheath. I really can't see how a test lab
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