[clug-talk] Slightly OT Power usage

Dave Watkins dave at davewatkins.net
Fri Nov 19 18:45:00 PST 2004

Hi All,

Concerning UPS's and surge protectors.......

I will only use line interactive UPS's in my shop or with my clients. The
protection offered by this type of UPS is far superior to the standard
battery backup. I've included a link to APC's white paper detailing the
different types of UPS's available. Basically they provide filtered,
conditioned and regulated power via the battery and avoid a direct
connection to the city grid choosing to run things through the battery
instead. Battery life is shortened slightly but that is a small price IMHO.


Concerning the use of surge protectors in most cases you get what you pay
for. It's as simple as that. Just for fun one day I hooked a battery charger
to a surge protector and placed a rheostat in line between the surge
protector and a 220 V power supply. I was surprised to see the range that
they would accept without tripping. That increase or decrease in voltage,
known as sags or surges, can cause as much damage to today's modern systems
and the data on them. Today's systems are more delicate due to the smaller
voltages required to operate. During a discussion with the City of Calgary's
Electrical Dept I was told that the voltage provided by the City can vary by
as much as 15% from 110V. I was also surprised to find out that this
variance is "normal" according to the City and within the contract we all
have accepted by using their power. Most surge protectors do not have the
circuitry within to react fast enough to these surges or sags. Another
consideration is the speed which a surge protector will kick in, sometimes
called the clamping voltage. With many of the cheaper units the damage has
been done before the protector realizes there has been a spike.

Sag   - slow decrease in supplied voltage
Surge - slow increase in supplied voltage
Spike - rapid increase in supplied voltage
Drop  - sudden loss of supply voltage

For what it's worth, I've used plenty of APC's products in the past and they
seem to work well. I have had to replace a few units under warranty that
failed AFTER they were hit with a spike in all but one case there was no
damage to the attached equipment and in the one case where a motherboard was
fried APC paid for a replacement board without any hassles. They were quite
happy to ask a few questions and cut a cheque for the new board while at the
same time sending out the replacement UPS.

Rider computers on 32nd Ave NE frequently have used UPS's and most have good
batteries in them. They will usually test them and mark the usage in
minutes. Replacement batteries can be purchased from Battery World if

Hope this helps someone......


Dave Watkins

Abacus Technologies

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