Actually the cheap meters are really good at reading the real power and ignoring the reactive power.
The power company wants you running at a power factor near one because the losses in their wiring and the capacity of their generators is related to the total CURRENT, rather than the total POWER, they supply.
If part of the current is reactive they still have their generating capacity consumed and still have to burn fuel to make up the resistive losses (which are real energy). But if you're too small a customer to rate two meters (one for real power, one for reactive) you don't pay for the reactive power and its resulting drain on their system.
It's cheaper for the power company to give you a flat rate for your power, assuming you're a "typical" consumer with typical loads and thus a typical fraction of reactive power use, and only measure the real part with a cheap meter. If your power factor is too low (i.e. you consume more than the percentage of reactive power they expected when they calculated your rate), they're billing you too little.[ Parent ]
Real power is the correct term to used to refer to total power used, not the resistive power used (watts), it's measured in VA (volt amps), and it is a summation each of the three power vectors.
This is how it works, we all believe that volts times amps is the power we use. That's only true with resistive loads. Where the power factor is 1, when we start adding inductive, and capacitive loads we start changing our power factor. Now volts times amps = VA or real power. Say we have a power factor of .8, hang our watt meter on the line and find out we are using 80 watts. Then we hang a volt meter, and an amp meter on the line, and find that we are at 10 volts, and drawing 10 amp... that's 100 watts? No, it's 100 VA, but only 80 watts, that leaves 20 VA, that is seen only as an inductive(or reactive)load. A watt meter can only measure the resistive component.
I stuck my kill-a-watt meter on my battery charger , and checked the the PF feed it. It was .69, lucky me, I'm getting 30% of that charge for free. The reason power companies don't make home consumers correct their PF, is because they are too small a customer to police. Now if you work your PF so that the watt meter doesn't move at all, they will show up at your door sooner or later.
Cya, Chris[ Parent ]
