Trust your what-hour err watt hour meter

Neither is really associated with measurement error. The downstream signal processing is.

It's not hard to make a meter that measures and integrates true power correctly. You can even buy chips that do all the hard work for you.

I suppose there can be a DC component of the power (like a diode+resistor load) that an AC-coupled meter (regular CT, Rogowski) would miss. So a real current-shunt sensor or DC-coupled Hall is more accurate.

The "Design an accurate true power meter with a 555" challenge!

I've got a house with a broken meter. The old analog style, the big wheel doesn't turn anymore. I guess after 50 years they wear out. I wonder how many months of $5 utility bills it will take for them to figure it out?

Ahh I think you are responsible for the meter, at least I was. I had mine replaced last summer... mostly it was just the outside box rusting away. (Maybe it was just the box I was responsible for... anyway I'd call your local electrician.)

George H.

Why?

Have a lawyer? The power company will try to bill you for the estimated power consumption over the time the meter was broken. They might even try to bill you for the maximum amount of power you could have possibly ever drawn givin you wire and transformer size. I had a power company try to pull that on me, when I pointed out the reason the meter didn't work was that their lineman had connected the service wrong!

Jon

The box, meter base, conduits and feed are the homeowner's responsibility. The meter, itself, is owned and maintained by the power company, and a seal is applied when it is installed.

Jon

Even when they used analog meters around here back in the day instead of the WiFi ones or whatever they have now, I don't think they read the meter every month but often just billed on "estimated usage" by looking at a representative sample

Yeah, whenever I'm getting something for free that I should be paying for I don't automatically assume the company is simply going to write it off out of the goodness of their hearts when they figure it out.

That's the part that surprises me. Maybe they know the house is empty and the few readings don't throw any alarms. The normal usage is nearly zero until the winter heat is turned on which is just three months. It's already off.

That's worrying for Joe Bloggs public. How are they ever going to contest a Smart Meter's accuracy ? How do we know that the old moving dial meters will be accurate with all today's 'switcher' electronics ? I think we all know that they respond correctly to a zero phase lead/ lag and start to be inaccurate as the phase lead/lag changes ( power factor)

Can I use a few opamps too?

A 555 could be used in a duty-cycle based multiplier. D.C. multipliers were popular for precision multiplies and divides and square roots once.

The old disk meters were very accurate for sinewave loads, at any power factor. In fact, it's hard to design an electronic meter as good as the old disks, one that will pass ANSI C12. About the only spec that's easier for an electronic meter to pass is tilt sensitivity.

I'm sure any smart meter has to be lab tested to C12 levels. Mine were.

The mechanical meters were better for stuff like lightning strikes, too.

Mathematically, as long as the voltage waveform remains sinusoidal, there is no energy in the current harmonics.

The LM324 or the '741, your choice! ;-)

On the left coast, PG&E uses 900 MHz spread spectrum for smartmeters, not wi-fi.

If I want, I can get hourly usage graphs from their web pile. Sample: The problem is that it's always 2-3 days behind and the web pages are really slow to load.

I can also download the data. This is a spreadsheet that I threw together to analyze cost and consumption trends to see how much I was saving by switching to LED lights, putting timers on phantom loads, and a little solar power during the summer: Notice how my monthly power consumption is going down (lower graph) while my monthly charges are going up. Grrr...

Some of this might be estimated usage, but I doubt it.

uA709?

We just got a nasty letter from PG&E. When we moved in here, everything was rewired and one meter was left totally disconnected. After 10 years, they got upset that we weren't paying for poweron that one; there were no bills either.

They sent a guy out to put a seal on the knife switch that had no wires going into it. They left the meter. I think they are happy now.

Probably allowed, IIRC it's older but better spec-ed than either, just not internally compensated and not unity-gain stable without a bunch of external parts...

It made a decent comparator, uncompensated. But the NPN diff pair would zener, and it liked to latch up.