On 28 Oct, Jeremy C B Nicoll wrote in message <4e7ce312deJeremy@xxxxxxxxxxxxxxxx>: > So, I'm wondering if I should buy a simple UPS. Can anyone recommend > one? What sort of VA rating? One I've seen was described as having - I > think - something like a 300W 500VA rating - how come the W figure isn't > the same as the VA one? Because VA and W aren't always the same thing... :-) If you were to run a truly resistive load of the UPS, then you would probably get 500W and 500VA out of it, as the power factor of a resistive load is 1.00. The problem is that even SMPS with power factor correction don't have a truly unity PF, and the loads will still appear to be inductive or capacitive instead of resistive. As a result, the UPS manufacturer will derate the wattage (real power) relative to the VA rating (apparent power). Usually, it seems, the figure of 60% is used. You need to work out the required rating based on the real power in W of the equipment that you connect. The VA rating then takes care of itself. -- Steve Fryatt - Leeds, England http://www.stevefryatt.org.uk/ --- To alter your preferences or leave the group, visit //www.freelists.org/list/iyonix-support Other info via //www.freelists.org/webpage/iyonix-support