power supply

[Technomage-hawke]

On Thursday 06 December 2007 08:19, keith smith wrote:
> A basic surge protector uses a capacitor.  Once the capacitor is at
> capacity it becomes a basic extension cord.
WRONG!

lets explain a little here..

firstly, the "surge protection devices" are not capacitors. they are MOV's 
(Metal Oxide Varistors) with a very fast clamp time and high current rating. 
However, they have a "shelf life" after which (usually about 10,000 
transients) they cease being functional (hence being nothing more than a 
regular multiplug extension).

Now, according to the IEEE, a scenario of "defense in depth" is often best.
we start right out at the mains breaker panel with a household MOV (10,000 AMP 
capable) and some large line filters (400 V AC each leg, low pass cutoff @ 
100 hz outer casing connected to a ground strap run to a ground spike right 
below the breaker box). 

on each outless in the house, a smaller version of that mains filter along 
with some smaller MOV's (4 should do).

additionally, any electronic equipment that you consider worth it (computer 
etc) should use a UPS/power conditioner (of course, at this point, the lines 
are pretty filtered, but, it never hurts).

lastly (and I do this with all my computer gear), install a block of MOV's, 
fuses and zener diodes at the output power blocks of your computers PSU (5.5 
V zeners for the 5 volt lines, 3.5 for the 3.3 V lines, etc) this way. if 
your PSU should have a catastrophic failure, at  least your motherboard (and 
all components therein) sre reasonably safe.

granted, this may cost some $$$, but after a while, it does pay for itself in 
reduced cost of repairs, losses, etc.

btw, on those circuits that run motors (such as your AC, refrigerator, 
washer/dryer, etc, place extra heavy duty MOV's and extra line filtering. 
this will reduce the transients caused by such devices from entering the rest 
of the house wiring.