Re: Average, RMS and Power Factor made easy!

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-uswest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<free0076-at-flinders.edu.au>

> Note in the above example you might still get charged for the power you
> aren't using... The metering systems that I have actually seen in my own
> area won't compensate for the power factor, and I doubt that yours does
> either, they just measure the current and charge you for it. So if you
> draw 10A and your capacitor isn't getting warm you probably are still
> paying for it.

This is not true. These meters are true Wattmeters. They don't look
at power factors or RMS values, but measure the amount of energy 
effectively consumed.
Old electromechanical units essentially integrate the force between 
two coils, one with a sample of the current being consumed and another 
with a current proportional to the voltage at the power line. This
force is proportional to the average power being consumed.
(This can be done in a variety of clever mechanical arrangements.)
More modern units do the same operation electronically, taking
samples of the voltage and of the current, multiplying them, and 
integrating the result.

Antonio Carlos M. de Queiroz