Watts or VA?

[empip]

A desktop PC :- Measured at the socket 243 V rms, 0.8 Amp rms, 152 watts, 194 VA, PF 0.78 ..
After 1 hr steady state at the above .. Do I pay for the 'active power' 153 W (0.153 units) or 'apparent power' 196 VA (possibly 0.196 units)?

Currently playing with a pair of ... these

 

[JohnD]

IIRC ordinary domestic meters only measure Watts. Some industrial installations (and I'm vague about this) have their power factor measured so they can be charged for kVA.

 

[empip]

JD,
Someone on Wikipedia said ... "...The significance of power factor lies in the fact that utility companies supply customers with volt-amperes, but bill them for watts. The relationship is (watts = volts x amperes x power factor). It is clear that power factors below 1.0 require a utility to generate more than the minimum volt-amperes necessary to supply the power (watts)..."
That equates to your thoughts...

Quoting IEE POWER FACTOR CORRECTION (pfc) article
"... A load with a power factor of, say, 0.8, results in much higher losses in the supply system and a higher bill for the consumer..."

I guess we eventually 'pay' for the losses through increased pricing.

After monitoring my PC for 1 hr 53 mins ( 1.883 hrs ) I have a kWh read out of 0.290 equating to 154 watt steady draw per hour.. This closely matches my 'Wattage' instant readout as opposed to the VA figure.

 

[Adam_151]

Your domestic meter will measure watts as opposed to VA, industrial users pay for VA, otherwise there would be no incentive for them to correct their power factor, and at those sorts of loads, it would cause problems for the grid with the wasteage through cable losses, etc

No doubt one day they'll start chargeing us domestic customers by VA....

 

[empip]

Cheers folks.
The little meters seem pretty good, several pieces of home equipment are producing data which matches their spec... remained cool in use with washing machine at 2.85 kW, then a tumble dryer running at 2kW.

If anyone is interested... An Elia 'table top' water boiler 2.2 litre used as permanent beverage water supply... 2 y/old
Spec: Reboil 795 Watt Keep warm 35 Watt

Actual measured.
Reboil 3.30 Arms 805 Watt PF 1.00
Warm 0.15 Arms 34 Watts 37 VA PF 0.91

24 hours normal usage 1.35 kWh (56.25 Watt per hour...)