[GreenKeys] High Winds

[Peter Gottlieb]

I spent several years as one of the senior design engineers at APC, who 
makes UPSes.  Part of the work involved testing computer power supplies 
to determine susceptibility to spikes, surges, dropouts etc. 

Computers are commodity items where margins are very slim.  
Consequently, there is a lot of pressure to reduce costs and it is 
sometimes amazing how cheaply things like power supplies are made.  And 
I mean "cheap" in the quality sense of the word.  We saw supplies which 
would latch up and fry on dropouts, auto-voltage ones which would decide 
to switch to 220 mode on a power spike (and stay there), and ones where 
the slightest dropout would cause a "power fail" signal to be sent 
despite a solid output.

The conclusion?  EVERY server and PC should have a UPS if you want any 
reliability.  Of course, you might expect a UPS manufacturer to say 
that, but it is the truth.  Considering how inexpensive it is to get a 
UPS, especially for us experimenters and tinkerers, this is a no-brainer 
as far as I am concerned.  APC is a very popular brand and there are 
literally millions of units out there.  All these units use lead-acid 
batteries, either 12 or 24 volts worth, and these batteries last AT MOST 
five years.  Many people throw out perfectly good units when the 
batteries go bad!  Now, on Ebay it is possible to pick up Smart-UPS 
units for $10-25 without batteries (for 600 or so VA).  The Smart-UPS 
units put out a sine wave and are pretty nice units.  They can also be 
picked up at hamfests very cheaply.  Do not have them shipped with 
batteries, that adds a lot to the shipping.  The smaller units use two 
12 volt 7 AH batteries common in alarm systems and available locally.  
Note:  they will work with larger batteries and give more run time, but 
charging will be slower after an outage, and seriously de-rate the unit 
for long run times at the transformer will get very hot as thermal mass 
is part of the design (example: I have a 900 VA unit hooked to a battery 
bank running my boiler, which draws under 250 VA with both pumps running).

Bottom line, it is extremely cheap (bordering on free) insurance to get 
a UPS, especially if you get a used one and deal with the batteries 
yourself.

Peter



George B. Hutchison wrote:
> GreenKeyers & ITTY - - -
>
> Yesterday we had several hours of high winds, and the power bumped 
> several times, which appeared to have nailed the server.
>
> An UPS will soon be added to minimize problems due to "Winter Power" 
> conditions.
>
> Y'all have a nice day and weekend.
>
> George - W7TTY - ITTY Central
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