Re: System Saver IIgs -- ID of burned part?-- line protection

[w_tom <w_tom1@usa.net>]

  You are confusing length of cord with connection to earth ground.  That is 6 feet
of cord, maybe 50 feet of in-the-wall 12 AWG to the fuse box, then some more distance
to earth ground.  All too far.  That distance between power strip and computer -
irrelevant by comparison.

  Effective surge protection uses wire as part of the surge protection system.  If a
surge is shunted to earth ground with 50' of wire between surge protector and
transistors, then that wire adds protection.  However, if the surge protector shunts
a surge at the appliance, then that long wire to earth ground encourages the surge to
find other, destructive, paths to earth ground.  One common path is through a
computer's modem to ground via the phone line - destructively.

  50' of 12 AWG wire may leave the surge protector at 15,000 volts during a 100 amp
surge.  That 15,000 volts will definitely finds alternative paths to earth ground -
because the surge protector was too far from earth ground.  Since the surge protector
was too close to the appliance, then one alternative path is often through the
appliance.

  If your MOVs explode or vaporize, then they were not just undersized.  They were
grossly undersized.  I believe that definition was expressly made in the previous
post.  MOVs should degrade slowly with use.  And when properly sized, that
degradation slows exponentially meaning that it is easy and not expensive to install
MOVs that will last longer than you.

170 V is not a surge.  It is well below what any surge protector will observe.

  UPSes, especially the sub $200 version connect your computer direct to AC mains
when not in battery backup mode.  That UPS relay is 1000 times too slow to afford any
surge protection.  Furthermore, destructive surges are common mode transients.  They
pass right through UPSes sometimes without ever being seen by the UPS.  Understand
the difference between common vs differential mode surges.  It is why UPSes are so
stingy with detailed specs.  Look at these for a better line UPS.  Notice on page 5 -
no common mode surge protection!:
     http://www.apcmedia.com/litpdfs/pdfs_new/996%2D0383e.pdf
  UPSes that are not grounded less than 10 feet to earth ground afford the same
protection as their power strip cousins. The components and surge protection circuits
are similar if not identical.  UPSes that provide effective surge protection are
installed as part of the building.   Plug-in UPSes provide surge protection from
surges that typically don't exist AND don't spec surge protection from surges that
commonly do the surge damage.

  Also UPSes, like power strips, often install undersized surge protection.
Effective surge protection shunts a surge to earth ground before it can enter the
building.  Ineffective surge protection was defined by any of four critical
characteristics.  Those characteristics are found in both plug-in UPSes and power
strip surge protectors.

Rubywand wrote:

> w_tom writes ...
> >
>
>      You observe that the length of the cord connecting a power strip to the AC
> line reduces the level of surge protection. If you focus upon equipment connected
> directly to the AC line, this is so. However, the concern is for equipment
> connected to the power strip-- i.e. the stuff you specifically aim to protect.
>
>      Since most, if not all, of a typical line surge's energy is going to pass
> through the cord and to the power strip, shouldn't the cord plus any in-line
> filter inductors act as a resistance which actually increases the effectiveness
> of clamping devices at the strip?
>
>      The main problem with depending upon MOV-protected power strips and 'power
> centers' (like System Saver IIgs) seems to be that, in some places on some AC
> lines, you will have relatively frequent events which blow the crap out of the
> MOV's. (And, really, how you supply whole-house protection against a rolling 170V
> surge on the AC mains for $50?)
>
>      As Tom Z and you have pointed out, MOV's may need to be replaced every so
> often. That is, surely, an annoyance. And, perhaps, the MOV running from Hot to
> 'Neutral' should be larger than a V130LA10. Even so, it is not clear why power
> strips and 'power centers' (like System Saver IIgs) with good MOV's should be
> written off as worthless.
>
>      The simplest solution is, probably, to install one or more Uninterruptible
> Power Supplies. You can plug your System Saver IIgs and power strips into an UPS
> and have the benefits of protection from surges and brown-outs plus the
> convenience of handy outlets and the added glitch protection supplied by the
> MOV's and filters in the SS and strips.
>
> Rubywand