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Posted by w_tom on 09/30/53 11:39
First all protectors - even the slow Gas Discharge Tubes (GDTs) -
were more than fast enough. That response time is hype to those who
never did the work, never learned the numbers, and will promote only
what they hear.
Second, joules rating of a MOV does not rate "maximum energy sinked
to ground". If true then every 300 joule protector would only vaporize
even on trivial transients. 300 joules - do the numbers. That is
virtually no protection. Joules is a measure of something else - that
basically defines protector life expectancy. The number of joules
'earthed' is massively more than the 300 joules on an ineffective
protector or the 1000 joules that is minimum size for an effective
'whole house' protector.
Yes, MOVs do have a maximum energy capacity. So do wires. 'Joules'
rating of a wire is no where near to the joules that a wire carries
into a load. 100 watt light bulb for one hour consumes 360,000 joules.
The wire consumes maybe 0.7 joules. Change wire to MOV and the same
concept is demonstrated. MOV will consume more joules, but MOV joules
are far below the energy shunted to earth.
Third, any surge protector intended for one time use is a scam
promoted by myth purveyors. Any protector that vaporized during a
surge was in violation of MOV manufacturer specs. Any protector that
vaporized during a surge provides no effective protection. However, to
have myth purveyors promote their products, ineffective plug-in
protector manufactures may intentionally undersize their products.
Then the naive will claim, "surge protector sacrificed itself to save
my computer". In reality, protection already inside that computer
saved that computer. Transient was just too small to harm that
computer. But adjacent protector was so grossly undersized as to
vaporize - operate in violation of MOV manufacturer specifications.
This to promote myths.
Other myths to promoted ineffective protectors is that $25,000
warranty. Good luck getting it honored. It is chock full of
exemptions. But those who never read details will use a silly warranty
as technical proof. Why not instead cite manufacturer specs for that
protector? Because manufacturer does not provide numerical specs that
claim to protect from a typically destructive type of transient. So
the naive will hype a warranty as if a warranty is technical proof.
Where are the numbers - technical proof of effectiveness? Such numbers
do not exist for ineffective plug-in protectors.
Daisy chaining protectors is not effecitve; actually makes the
protection worse. A protector is nothing more than a temporary
connection to protection - earth ground. Connection to earth ground
must be short, direct, and independent. Short as in 'less than 10
feet'. Daisy chaining only add more 'six foot' wires (and other
problems) to that earthing connection. Let's see. Six feet of power
cord. 50 feet of wire in the wall. How many feet from breaker box to
earth ground? IOW the plug-in protectors has all but no earth ground.
Other factor that make it worse: Many sharp wire bends. Numerous
splices. Bundled with other non-earthing wires. All conspire to make
earth ground even (electrically) farther.
Where does Felix even mention earth ground. Not just any ground.
Earthing (not just ground) defines quality of a protector. Plug-in
manufacturers hope we never discuss earthing. A protector is only as
effective as its earth ground ... which plug-in protectors must avoid
to sell their ineffective products.
What are manufacturers of effective protectors? Square D,
Cutler-Hammer, Leviton, Intermatic, GE, Polyphaser, and Siemens. Note
they are names of responsible manufacturers. What names are found on
ineffective protectors? APC, Tripplite, and Belkin. Effective
protectors can be purchased in Home Depot, Lowes, and most electrical
supply houses. Never saw an effective protector sold in Sears, Kmart,
Office Max, Radio Shack, Circuit City, Staples, Best Buy, or Walmart.
But then ineffecitve protectors are easy to identify. **No dedicated
connection to earth ground AND manufacturer avoid discussing
earthing.** Ineffective as in plug-in protectors that forget to
mention ... they don't even claim to protect from a typically
destructive type of surge. They claim protection from another type AND
hope you will *assume* that is protection from all types of surges.
A protector is only as effective as its earth ground - which explains
those exemptions on a big buck warranty, and why so many ineffective
plug-in protectors are grossly undersized ... as to be destroyed by
only one surge.
felix...@yahoo.com wrote:
> Actually this is not quite a correct version of how a surge protector
> works.
>
> Real surge protectors typically have the following specifications:
> 1. Peak voltage allowed to pass
> 2. Response time to respond to over-voltage
> 3. Maximum energy sinked to ground before destruction
>
> When a voltage spike arrives at the surge protector, if it exceeds the
> peak limit, the surge protector will drop to very low resistance and
> begin diverting the current to ground. The response time is critical in
> determining how much of the spike's energy will reach the protected
> equipment. It's not the voltage of the spike that matters, it's the
> total energy that gets through - i.e., voltage x current x time, with
> the time being the critical factor that's up to the surge protector.
>
> Surge protectors also have a maximum energy capacity. If it is
> exceeded, the surge protector will be destroyed, which may allow
> additional energy to get through to the now-unprotected equipment (but
> hopefully by then a line fuse or breaker in the current loop will have
> opened). Many types of surge protectors are intended for one-time-use -
> if they divert a surge, they are permanently affected, and need to be
> replaced.
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