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

[Rubywand <rubywand@swbell.net>]

w_tom writes ...
>
> Tom Zuchowski wrote:
> 
> > FWIW, MOV surge protectors are like crash helmets, they are good for one (1)
> > use and then you have to replace them.
> >
> > MOV's are also subject to "wear and tear". Every time they stop a surge,
> > they lose some effectiveness, until the day comes when they fry like yours.
> > People who are serious about surge protection will replace all of their
> > MOV's once per year or thereabouts.
>
>   Ineffective surge protection is defined by any of four critical
> characteristics: 1) too close to transistors, 2) too far from earth ground, 3)
> too expensive to protect only one appliance,
> and 4) too undersized for effective surge protection.  
> Any surge protector that is only good for one surge is not
> just undersized; it is probably grossly undersized - ineffective surge
> protection.
> 
>   Three MOVs in the Apple II are how surge protection was once installed in all
> appliances of and before that period.  Those $0.05 and $0.30 components are no
> longer installed because, in electronic appliances, they violate critical
> characteristics one,  two, and four.   Plug-in surge protection, such as the
> power strip, usually violates all four critical characteristics.
> 
>   Effective surge protection is properly sized so as to shunt a surge to earth
> ground AND remain operational for the next surge.  Joules is a benchmark of
> surge protector life expectancy.  However derate the speced joules
> for a plug-in surge protector to as little as 1/3rd.
> IOW a plug-in surge protector rated only
> at 345 joule may actually be 115 joules and never more than 230 joules in surge
> protection.  Just another reason why plug-in surge protectors violate critical
> characteristic four.
> 
>   Effective surge protection protects everything in the building for about $1
> per protected appliance.  If V1, V2, and V3 are MOVs (such as the V130LA10),
> don't worry about them.  If for no other reason, they are too far from earth
> ground to be considered grounded.    Instead install effective surge protection
> connected less than 10 feet to central earth ground.  That less than $50 'whole
> house' surge protector will effectively protect the Apple II and other
> electronic appliances - typically for more than 10 years..
> 

     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