Subject: Re: Lasers with Lens Flar
From: "Daniel J. McCoy" <[email-masked]>
To: Multiple recipients of list <[email-masked]>
Date: Mon, 18 Dec 1995 19:47:45 -0500

At 04:37 AM 12/18/95 -0500, you wrote:
>Just check the label on the back of each piece of equipment to determine 
>the number of Watts.  Add up all the watts and multiply by the number of 
>hours.  That gives you watt-hours so divide by 1000 to get kilowatt-hours.  
>Multiply kilowatt-hours by the rate you pay ($/kw-h) and you have it!

Warning...  Do NOT use the WATTS value specified on your power supply as a
basis of how much it is consuming.  That value is typically the MAXIMUM
amount rather than an actual ammount.  A couple years back, a UPS
manufacturer (BEST) sent me an information packet on their products and how
to convert WATTs to VA (volts per ampere) that UPS manufacturers also use.
It gave you a worksheet to calculate the UPS that would suit your needs.  At
the time, I had an Amiga 3000 w/ 200W power supply, a SCSI sub-system with a
200W power supply and an monitor.  Doing the conversion to VA and then
adding 'em all up and adding a fudge-factor for future growth, I ended up
with a 1.3KVA UPS!  When that 66 pound beastie came in, I plugged everything
in and checked the UPS load...  25% load on 1.3KVA with 70 minutes of backup
time!  HOLY MOLY!  And that is WITH the monitor ON!  NOW I only have a PC
hooked up to it with a 270W+ power supply and it only puts a 5% load on the
UPS with a run-time of >99 minutes (only two digit LED display  :) ).  Turn
the monitor on and it's 15-20%.  :)  Obviously, I overbought by a LONG shot!
I would have returned it if it weren't 66 pounds!  B^)

But the beast came in handy during that earthquake So. CA had in '94.  My
computer was happily rendering an animation 30 minutes after we lost power.
Plus, I had it supplying power to a radio tuned to the news.  Once I turned
the computer off, I probably could have ran the radio for hours...  :)

At any rate, the actual power consumption will always be lower than the
value specified on the power supply.  

Dan
(Who should have KNOWN better!)
--
Daniel J. McCoy - [email-masked] or [email-masked]
WWW - http://www.westworld.com/~djmccoy