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

[Stephen Shaw <xstephenx@apple2.org.za>]

Stay away from the APCC ups's. Ever tried to get ANY repair info from APCC!!!!
They cite "commercial confidentiality"!


On Mon, 2 Jul 2001 15:28:21 -0700, Keith Olson wrote:

> [comments inline]
>
>
> "Rubywand" <rubywand@swbell.net> wrote in message
> 3B39D378.A133B669@swbell.net">news:3B39D378.A133B669@swbell.net...
>
> -----8<-----
>
>> >   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.
>>
>>      What you call a "surge" is often referred to as a "spike".
>>
>>      UPS's work fine as protection against relatively long duration
>> over/under voltage situations. This, in turn, works to protect against
>> spiking. Spikes are more likely during sustained off-voltage (high or low)
>> situations. Just being taken off-line and placed on inverter power for a
> few
>> seconds prevents exposure to especially dangerous spikes.
>>
>>
>> > Furthermore, destructive surges are common mode transients.
>>
>>      Which, really, is very fortunate.
>>
>>
>>
>> > 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
>
> One minor (or not so minor) point:  a *true* UPS (~U~ninterruptable ~P~ower
> ~S~upply) contains two separate circuits - a charger, and an invertor.
> When line voltage is lost, the invertor is not effected at all.  It simply
> keeps on doing what it always did. (i.e. converting DC from the battery to
> AC) This separation also provides buffering from overvoltages and
> brownouts. Even a power surge that totally blows out the charger might not
> kill the battery, thus allowing you time to shut everything down.
>
> What many companies advertise as a 'UPS' (notice the quotes) is actually an
> SPS (~S~tandby ~P~ower ~S~upply), which provides (generally) unfiltered AC
> power straight from the line while keeping a backup battery topped up.
> When power is lost, an invertor kicks in to provide power.  While both
> circuits use a charger & invertor combo, it doesn't take a genius to notice
> that an SPS doesn't need components that are as robust, as they are only
> needed once in a while, instead of constantly, as is the case with a USP.
> This explains why a UPS can cost twice as much as an equivalent SPS.  If
> you want to know if you are getting a true UPS, just ask the salesman what
> the switching time is.  If he gives you any answer other than 'none', ask
> him if he even knows the difference between a UPS and an SPS.....gently.
>
> Hope this helps
> Keith Olson

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