Hi Chuck,

120Volts is the rms voltage so if current is likewise stated as an rms
value, and they are in phase, then their product is power. However, a key
point here is whether the current and voltage through the load are in
phase. If they are not, then you need to multiply by the cosine of the
phase angle between them, which is often called the power factor. Only a
purely resistive load will have a power factor of 1, any inductance or
capacitance will make it less than 1.

So, an AC power supply (like a UPS), has some defined rms output voltage
(120 in this case). It then could possibly have two limits: a current limit
and a power limit. Because of the possibility that the load may not have a
power factor of 1 (if the current and voltage are out of phase), it is not
enough to just specify a current limit. If they tell you both limits, you
need to make sure you do not exceed either one. The Va you are using is
simply the product of (rms, I'm fairly sure) voltage and current without
regard to power factor. The W you are consuming is the Va times the power
factor.

Sean


At 03:15 PM 3/28/2003 -0600, you wrote:
>http://www.hp.com/racksolutions/prodinfo/power_access/ups_ux.html
>
>PowerTrust II-LR 2.0kVa(1.4kW) UPS 120V
>
>
>Anyone have a clue on the dual labeling of UPS power capacity?
>
>When dealing with AC is power (W) not equal to I x V but rather I X V(RMS)?
>
>
>PC power supplies are rated in watts but should it really be the volt x
>amp total used when calculating UPS load?
>
>Here's a listing from APC which labels everything in VA:
>http://www.apc.com/products/family/index.cfm?id=165&tab=models&displayfocus=Rack
>
>APC Smart-UPS 2200VA RM 3U 120V
>
>
>thanks
>chuckc
>
>--
>http://www.piclist.com hint: PICList Posts must start with ONE topic:
>[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads