I am in desperate need of some help.
I want to purchase a UPS battery backup surge protection device but I am lost when looking at all of my options. Between the VA rating, Watts rating, joule rating, and everything else I don't know what is best. I have looked at manufacture websites and they are not of much help. Actually they confuse me more in the fact that they state the product is a UPS - [b]meaning it actually runs the computer off of the battery all the time[/b
The UPS has a filter system inside that prevents spikes, surges, and brownouts. It will maintain line voltage at all times, but will only run off of the battery in the event of a power outage.
To determine the proper size UPS you will need to know what the current draw of you system is, this will be expressed in either amps (amperes), or in Watts.(W) And you will also need to know the voltage (V) is, house hold voltage in the US is 110V, in other countries it runs between 230V and 240V. Once you know what the voltage and amps are you multiply these to find the Volt Amps (VA). Example, 110V X 5amps = 550VA
Some equipment will provide the current information is Watts, to convert Watts to Amps Davide the Watts by the line voltage. Example, 200W divided by 110V = 1.8amps.
The problem now is to find the total amount of watts your system uses, some equipment will have this information of the back of it, others you may need to contact the manufacturer to obtain it. Another way would be to plug you system into a power strip and then read the amperage with a amp-meter. If you plug a laser printer into the UPS you need to know that the running current amount listed may not include the load when the heater is active, it could be rated as a 2amp load and actually draw 5amps when the heater is active.
There is a good article if you would like to read more about this, you can find it here.
In this article there is a paragraph titled What size UPS do I need?, and in this paragraph is a link to UPS Sizing Guide & Extended Run Time Calculator, you may find this useful also.
Edited by dc3, 29 October 2006 - 11:54 PM.