[Leaplist] UPS advice needed

[patrick]

andrei raevsky wrote:
> JeezUS!  I had not idea that this kind of equipment was so prone to
> burning.  So each UPS user risks a fire in his house each time he leaves a
> UPS running?!
> 

Don't forget all those "Surge Suppressor" outlet strips, that also have
"shotgun" MOVs. Cheap ones have one MOV installed, Hot (Black) to Ground
(Green).

MOV - Metal Oxide Varister.  A Silicon based device with a PN type
junction.  As voltage builds on the "P" type material on one side, it
can change the state of the barrier or "depleted" zone.  Eventually,
enough electrons have migrated so that the "N" type material will
conduct to ground (on the other side).

If I take the black, white and the green wires of an extension cord,
with multiple outlets, and each gets a MOV that the other side goes to a
different leg, and none get more than two connections, it would be
called "common mode transient or spike suppression".  Like a perfect
equilateral triangle.

Each wire is protected from all voltages above 178 Volts.  That is the
voltage at which a 115Volt MOV starts to actually conduct!

But, now, in a single MOV or a triple MOV system, the high voltage hits
the MOV(s) at the same time that the high current does, so the device,
being 'cold', is instantly heated by the mass of electrons flowing,
while the barrier is not actually fully conductive, and the MOV shatters
in a very short time, causing a huge noise, accompanied by smoke and
flames, followed by the stench of melting insulation.

Proper design puts 12 turns of #14 AWG wire, as if it had been wrapped
around a pencil, between the Hot (Black) wire connection and the MOV
that connects it to another leg.  A single inductor like this one,
anywhere in the ciruit, will delay current behind voltage by 90 degrees,
or one quarter of an AC cycle!  Most spikes come in on the black, though
Lightning prefers the Neutral (white) and Ground (Green) legs.

Nothing could protect from lighting strikes. We are concerned with
lesser evils.

That inductor gives plenty of time for 'warm up' and full conductivity
of the silicon strata comprising the MOV.

This design was foremost in most professional grade products built  in
the 1980's and 1990's but, goods being made by cheap labor seem to leave
the inductors out.  Save a penny on 10 million units, and it adds up to
million$.  Perhaps, something got lost in translation to offshore
assembly lines.

I have yet to find a Surge Supressor outlet strip with proper
construction.  I open them, and put in my own coil of wire, insulated of
course, in the proper color.

Those make it through years of the 22,000 spikes per hour that exceed
15,000 volts, that are on the average modern commercial AC distribution
lines.

Most are caused by the EMF back surge (Elecro Motive Force on startup of
a motor, has a sag followed by a huge spike of short duration) of Air
Conditioning, Refrigeration, and modern machines, followed by generation
of high frequency noise all the time it runs.  The high inductance, and
the discharge of the 'start' and 'run' motor capacitors all contribute
to this.

* Put an AM radio within three to five feet of a kitchen appliance,
 (Garbage  Disposal, Blender, Mixer, Can Opener) and listen to the
 spikes that are generated when it is turned on.

Try to count them, multiply by the ten thousand homes on your
sub-station, all contributing to the din of noise.  Then add the
cacophony of 1,000 restaurants and stores, table saws and wood routers,
Stop N' Robs, with dozens of coolers, fans, motors, faulty flourescent
light ballasts, that are all on the typical sub-station.

It's a wonder our appliances even last a year!

Any questions?

Next week: Wye and Delta AC power generation and distribution with
Hydro, Conventional, and Nuclear powered generator systems.