wrote:
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.

That is a quote from UL. Contrast that with Martzloff:
"The fact of the matter is that nowadays, most electronic appliances
have an inherent immunity level of at least 600 V to 800 V, so that the
clamping voltages of 330 V widely offered by TVSS [surge suppressor]
manufacturers are really not necessary. Objective assessment of the
situation leads to the conclusion that the 330 V clamping level,
promoted by a few manufacturers, was encouraged by the promulgation of
UL Std 1449, showing that voltage as the lowest in a series of possible
clamping voltages for 120 V circuits. Thus was created the downward
auction of 'lower is better' notwithstanding the objections raised by
several researchers and well-informed manufacturers. One of the
consequences of this downward auction can be premature ageing of TVSS
that are called upon to carry surge currents as the result of relatively
low transient voltages that would not put equipment in jeopardy."

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

I believe it is required by UL to be on the package or literature.


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.

I would like to know the Joule ratings. The problem, as you say, is
there is no standard way to measure the energy rating and some
manufacturers apparently use questionable ratings. That has led some
other reputable manufacturers, like SquareD, to not include Joule ratings.

Peak surge current is directly related to the energy rating. w_'s
recommended 50,000A surge current rating is way beyond what you will get
at a service panel, but it represents a high energy rating which means
long life.

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bud--