"w_tom" wrote in message
...
Please feel free to show us an MOV datasheet that says
... good surge protectors are destroyed by big surges just
as they are designed to do. The good one FAIL closed
circuit where protection is even better!

That claim is classic urban myth. MOV data sheets define
normal operation. MOV is at end of life typically when it
degrades by about 5%. How can it degrade 5% and yet
vaporize? It cannot. Bottom line remains - a properly sized
protector shunts the transient and remains fully operational.
Eventually MOV degrades; does not vaporize. Vaporizing is
when the MOV grossly exceeds manufacturer specification - is
grossly undersized for the task. But purveyors of undersized
and ineffective protectors want consumers to believe their
overpriced protector should vaporize on every surge. Scam is
the better word.

Gibber ignored.

In the meantime, there is no topology in electronic
circuits.

And this wacko nonsense is from the guy who brought up DA design! At high
frequency it is most ALL about topology!

Electrically, a shunt mode protector is not
"between" the appliance and a surge no matter how much junk
science topology is rationalized.

Did you ever hear about the speed of light or about 1 foot per nanosecond?

But then this thread is
full of myth purveyors promoting such junk science reasoning -
such as MOVs are designed to protect by vaporizing. Which
plug-in manufacturer do you work for, Ron Reaugh?

Vaporizing...are you gonna bring in Klingons now as we seem to be having a
bit to drink?

Ron Reaugh wrote:
"w_tom" wrote in message
...
Was UPS between AC mains and computer? No.

Wrong. Topologically the UPS is "between".

UPS and computer both connect to AC mains just like
light bulbs. In fact it would be same protection if both
computer and UPS shared same wall receptacle.

WRONG! About a critical 10 nanoseconds WRONG nevermind the
impedances and common mode condiderations!

Any transient from the receptacle confronts UPS and
computer equally.

Not in the critical time domain.

However protection inside a UPS is often so grossly
undersized that a surge too small to damage a computer
might still damage the UPS. Furthermore, some computers
can even act as surge protectors - shunt a destructive
surge so that it does not seek earth ground via other
computers.

Until you define specific circuits - including how
every wall receptacle is wired, then I cannot provide
more information.

I cannot say exactly why that particular event happened.
But above is one reason why a UPS may be damaged and
computer is not.

NO, the first component with surge suppression topologically
is usually the one that takes the HIT. Do you suppose that's
by design?

Computer power supplies have internal protection.
Protection so sufficient that there is little adjacent to a
power supply that can enhance protection. But computer
internal protection can be overwhelmed if destructive
transients are not earthed before entering the building.

OH, you mean unless the building is a heavily constructed
Faraday cage and all wiring has feedthru bypass and surge
suppression, then a destructive transient could get through
and that has NOTHING to do with you high transient impedance
ground wire.. Why is it that we all knew that?

Bottom line is this. You had UPS failure. Therefore you
have no effective surge protection. Even surge protectors
must not be damaged due to a surge.

HUH, frequently good surge protectors are destroyed by big
surges just as they are designed to do. The good one FAIL
closed circuit where protection is even better!

To provide a better answer, do as I do - autopsy the dead
body. Replace the defective part to learn what has actually
been damaged. Autopsy only complete when the failed unit is
fully functional.
...
From Sun Microsystems planning guide:
http://www.sun.com/servers/white-pap...ning-guide.pdf
Lightning surges cannot be stopped, but they can be diverted.
The plans for the data center should be thoroughly reviewed
to identify any paths for surge entry into the data center.
Surge arrestors can be designed into the system to help
mitigate the potential for lightning damage within the data
center. These should divert the power of the surge by
providing a path to ground for the surge energy. Protection
should be placed on both the primary and secondary side of
the service transformer. It is also necessary to protect
against surges through the communications lines. The
specific design of the lightning protection system for the
data center will be dependent on the design of the building
and utilities and existing protection measures.