DIYbanter - View Single Post - Measuring power consumption of immersion heater?

Adrian C

wrote:

If they are charging per kWh, power factor is irrelevant.

T

Tom, the issue is *how* the meter makes a measurement that can be
accurately displayed as "real power" - Watts - what the domestic
customer is billed for.

The device can measure voltage of the supply.
The device can measure current drawn.

That's VA.

To arrive at Watts, it has to calculate (guess, fiddle) what the power
factor is and this is where the over reading inaccuracies result,
especially with low current devices, and cheapo gadgets of this sort.

Power factor of the supply? What's that then?

--
Adrian C