On May 7, 2:37*pm, VWWall wrote:
wrote:
I think the UL requires only that the MOVs don't start a fire when
exposed to conditions which cause their break-down. *They don't rate
their ability to function as "surgeprotectors".
UL evaluatessurgesuppressors for fire, electric shock and personal
injury hazards, and also measures and categorizes the devices for how
much voltage they can "clamp," thus preventing excess voltage from
passing through to electronic equipment. UL refers to this as a
"suppressed voltage rating," with ranges from 330V (volts) to 4000V.
Believe it or not, the lower the rating, the better the protection.
How can one find this rating for a particular device?
Look for ul1449 330v or 400 for example, or surge voltage rating SVR
330v or Clamping Category 330v
Whateversurgesuppression protection you're looking for, make sure
thesurgesuppressor has been tested and Listed to the stringent
requirements of UL 1449, the Standard for Transient VoltageSurge
Suppressors.
http://www.ul.com/consumers/surge.html
"The unpredictable nature of surges makes it difficult to suppress them;
you never know when, how long or how powerful they will be. In some
cases, asurgemay have a higher energy level than the device can
handle. When this happens, thesurgesuppressor may be damaged and lose
its ability to provide protection against future surges."
MOV’s and surge protectors are like tires on your car, the more you
use them the shorter useful life, mistreat them, the shorter the
useful life, too small or light weight the shorter the useful life.
Ul 1449 certification take care of the too small or light weight.
Proper selection for problem locations is the key to protection.
I'm happy to see that UL agrees! *They don't seem to put any evaluation
of this parameter, unless the "suppressed voltage rating" includes the
Jules rating of the MOVs.
Don’t pay attention to joules on surge protectors, no standard to
measure, a better and recommended rating is “Peak Surge Current” the
higher the better.
http://ulstandardsinfonet.ul.com/toc...=s&fn=1449.toc
Thanks for the reference.
--
Virg Wall, P.E.