How can I calculate how much Watts and joules Id want in a UPC (battery backup)?
What Size UPS? UPS manufacturers spend a lot of time working out methods of sizing. Much of this comes from the consumer or light commercial market, where the general population is not necessarily electrically knowledgeable. The UPS is very much like a battery. It has a load rating for a period of time. In a battery, this would be so many amp/hours (AH). The UPS typically has a Volt-ampere (VA)/min rating. The most difficult part, obviously, is to calculate the correct VA. A good rule of thumb to remember is that most computers and other such devices have a poor power factor; therefore, using the device wattage is not recommended. The Power Factor is the real Power (measured in Watts) divided by the Apparent Power. So: Power Factor (pf) = Watts of Average Real Power / (Volts * Amperes) Another way of expressing this: Power = Voltage x Current x Power Factor Power Factor – Most desktop PCs present a nonlinear load to the AC supply. The voltage and current are somewhat out of phase. This
Check all your devices for wattage and amperage (usually at the back of device) and calculate using the formula bellow: How is the right size of UPS selected? Typically, a UPS has a VA rating and there are two quick ways in which the necessary VA rating can be assessed. If the power demand of the equipment to be protected is expressed in Watts, the VA rating of the required UPS can be calculated by dividing the number of Watts by 0.7. Alternatively, the VA rating of the required UPS can be calculated by multiplying the power input requirement of the equipment expressed in amps by 230. The amps input is shown on the equipment’s CE Mark plate. http://www.sourceups.co.uk/index.php?option=com_content&task=view&id=19&Itemid=33 Choosing the right UPS What does a UPS do? UPS is designed to provide an alternative source of power to electrical equipment in the event of an irregularity
