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Thread ID: 23178	2002-08-09 06:31:00	UPS	Heather P (163)	Press F1

Post ID	Timestamp	Content	User
69673	2002-08-12 04:53:00	There is a difference between watts and VA in AC power. A heater rated as 2300 W will use 10 A at 230 V, regardless of whether it is AC or DC. It is non-reactive (purely resistive). Similarly, A 230 W incandescent bulb will use 1A (AC or DC). A fluorescent tube (which has an inductive ballast) might be rated at 65 W. It will not use (65/230) A -- 65 VA. It will draw more like (100/230) A -- 100 VA. This is because the current "sine" wave is lagging the voltage. That would indicate a "power factor" of .65 . A fitting usually has a capacitor across it to compensate for the power factor (because you pay for watts, the supplier has to provide volts * amps). That figure you quote of 320 VA (200 W) indicates that the unit is expected to feed units with pf of .625 . The switchmode power supplies of computers and monitors are probably not all that bad. But you should add up the current ratings of the equipment you are plugging in, and use the VA rating to specify a unit. You don't need to grossly over-specify. It will be running for only 5 minutes or so. A heavier duty one might be "better' for surge protection etc, but it might not. It will cost more.	Graham L (2)
69674	2002-08-12 06:06:00	Heather It may be a little off the topic, but I looked into this for a remote data logging system up Gisborne way. (they have some of the worst power quality in NZ - sush its a secret) ;) We gave up in the end and just used a laptop. Not really an option when you already have 2 computers, but something to think about. :)	vanman (959)
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