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
interpretation lies.
All other parts of the board must remain "undamaged". The "no fire
hazard" is a significant weakening of the general interpretation and
probably represents aggressive engineering judgement.
Jon.
j...@aol.com wrote:
Hello All:
I am hoping that some of you can help clarify the intent of requirement R9-20
in Telcordia GR-1089. Taken literally, the requirement says that there shall
be no damage to equipment, conductors, or components when the DC power supply
is shorted at the load. This could even be interpreted to preclude the use
of a fuse that has to be replaced.
One test lab has told me that as long as no fire hazard is created from this
test, it is considered to have been passed. Needless to say, this differs a
bit from the literal interpretation.
I guess it would help if I had a better feel for the overall goal of the
short circuit testing. Any insight on this would be most appreciated.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848
http://www.randolph-telecom.com
