Hi treg members,
I am researching a method of implementing UL 1950 3rd edition safety
circuitry into an international modem. My goal is functional survival
of FCC 68 lightening surges and nonfunctional (pass) after UL 1950
power-line cross. This is generally a simple solution (1 amp slo-blow
250V in series with T/R). Our product is a PC card modem though, and
does not have the necessary room for a fuse of this type. What I am
particularly interested in is information regarding the likelihood of
lightning strikes contrasted with the likelihood of a power-line
cross. The problem is the cost benefit ratio of implementing this
solution vs. passing both tests in a nonfunctional state. To be
concise my interests are as follows.
1. Does anyone know of such a study?
2. Has anyone succeeded at this using surface mount devices only?
3. Am I overlooking something obvious?
I am aware of the Polyswitch but it doesn't fit our size
constraints. It is ideal in every other sense. We currently use a
sidactor to pass FCC 68 functionally but have not been able to source
a fuse that meets our requirements.
Any information or assistance in this would be greatly appreciated.
Sincerely,
Gary L. Schlussler
TDK Systems Inc.
P.S. I am aware that UL 1950 3rd edition is not mandatory until 2000,
but am trying to solve this now. I would really like to survive both
tests fully functional but do not see that as a possibility at this
time.
