Hopefully you will forgive me hijacking the post but this brings up a question I have had for a long time. What on earth is a "volt-amp". My logic would state that is is the same as a watt, which is volts x amps, as you probably well know. So what on earth is is?
Confused..... Albert --- In Repeater-Builder@yahoogroups.com, John Barrett <[EMAIL PROTECTED]> wrote: > > low power factors are bad -- you pay for the higher VA, but are only > using the lower watts to do actual work !! > > I'm really surprised that USP doesn't have a PFC front end to bring > everything back into line. > > Bob M. wrote: > > > > I have an APC SU2200 (SmartUPS, 2200VA) 3U tall, that I put new > > batteries in a few months ago. So far it's just sitting, plugged in, > > turned off, with no load. I got curious as to how much power it was > > sucking out of the wall outlet, so I plugged the UPS into my > > Kill-A-Watt device and plugged that into the wall. Here are the > > numbers I observed: > > > > 122.2 Volts > > 1.48 Amps > > 31 Watts > > 181 Volt-Amps > > 0.17 Power Factor > > > > The values were identical with the unit turned on, also with no load. > > The only thing running inside the UPS is the battery charger; the > > inverter is completely bypassed and is not running. > > > > I then ran the UPS into a test cycle, again with no load, but this > > time the inverter turned on and powered the load, thus disconnecting > > itself from the commercial AC power. Surprisingly, there was still a > > little bit of power being used, probably by the transformer and line > > sampling circuit. Here are the readings I got during the self- test: > > > > 122.4 Volts > > 0.09 Amps > > 0 Watts > > 11 Volt-Amps > > 0.06 Power Factor > > > > As far as I know, the utility's kilowatt-hour meter on the side of my > > house, which is a rotating aluminum-disc style, measures WATTS, not > > Volt-Amps. Somehow APC has managed to get their charging circuit to > > draw a lot of current while keeping the power factor and Wattage power > > extremely low. I suspect it's highly capacitive. > > > > So here's where you all get to jump in. Is this UPS costing me a lot > > just to keep the batteries charged (180 VA) or am I only being charged > > for the wattage it draws? > > > > Bob M. > > > > >
