I’m confused as to how we are supposed to have faith that smart energy meters are accurate – there’s very little information out there about how they work.
I searched the sub and previous threads about smart meters don’t have any scientific explanations, mostly just the social/practical issues of phasing out old meters and retrofitting new ones.
Filing under Technology but this could be physics or engineering I suppose
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Let’s clear it up – do you *specifically* have an issue with smart meters and had zero doubt about the old (electro)mechanical meters being accurate? If so, I’m not sure I really get where you’re coming from. Smart meters just have the same metering hardware, but instead of the output being connected to a little rotating number wheel you need to ogle and write down on a piece of paper, they are connected to a digital encoder that counts the rotations instead.
As with pretty much all types of measuring equipment, it starts with a reference load.
When it comes to electricity, it’s a gadget that is deliberately constructed to consume an amount of power that is as near a specific number as possible, so that you can hook up that load for (insert number of seconds/minutes/hours) to a new power meter, and then check the reading afterwards.
If the new meter fall within an acceptable bracket (typically 1-2% on electrical power meters specifically) it’s labeled with its actual measured error and shipped out.
When the power company wants to verify that a meter shows an accurate reading, they buy a verification meter. A portable, plenty more expensive, power meter in a bag-formfactor that is immediately sent to a reference load owner (that acts as an accreditation institute) for verification. Once it’s verified, it’s considered good enough for verifications for a year to come.
When they want to verify the power meter in your home, they basically hook up their own verification power meter they brought with them and do a reading that lasts a reasonable while (the longer the more accurate) and COMPARE the reading from the verification instrument with the reading from the installed power meter.
The allowed inaccuracy is often very well regulated (around there, the law says straight out that a power meter that is 5% inaccurate, no matter who whose advantage must be immediately replaced) and if the installed meter falls outside of the acceptable bracket, it’s replaced.
Most of the time, the power company has no legal obligation to visit their power meters and verify them. Instead, they do it at their own insistence and on customer insistence if something statistically speaking seems to be off.
For sad reasons, the number one thing they find when they verify a meter is not that the meter is broken, but rather that the customer appears to be deliberately stealing energy.
Regulations for central heating, central cooling, gas and so on are quite similar. A regulatory body establishes what kind of deviation is allowed on a meter (again, it’s always a percentage) and as long as everyone involved feels that there ain’t a particular inaccuracy, they keep going.
>being confused at how something seemingly really “physical” like gas moving through a pipe can be turned into digital data.
ok, let’s do it in steps for water/gas:
1- you build a pipe with a helix inside,[similar to this mill](https://images.freeimages.com/images/large-previews/ad9/water-mill-1441178.jpg) but smaller and all enclosed in the pipe, now if water (or air/gas) pass through it the thing rotate proportional to how much water/gas patt through.
fine, we converted “something physical like gas” into a rotation.
2-we can install some[gears like the one you find in a clock](https://i5.walmartimages.com/asr/25520dc1-58ff-47a0-bf1b-c0ab1217b76b_1.6a3ee74bcbde6c4854290c3b3f610e9a.jpeg) and you converted rotation into a number
good, now we built the analog version of the meter.
what about the digital one?
simple, we change the normal gear with an [“electronic one”, see here](https://www.analogictips.com/wp-content/uploads/2018/02/Analog_rotary-encoder_Pt1-opener.jpg) that gear is full of holes, there is one led on one side and a light sensor on the other side, as the thing rotate the receiver will notice that there is light/no light/light no light…. and for each change it can count +1
there are also more [complex one like this](https://www.electricalandcontrol.com/wp-content/uploads/2021/07/Absolute-encoder.png) with multiple holes and receivers, that one can undersand also the direction of rotation given the unique sequence.
after you connect the receiver to a microcontroller you have digital data and you can send it over the internet or whatever
Twinkle twinkle little star, `V` is equal to `IR`. Therefore you can determine the current flowing through a junction of known resistance by measuring the voltage drop across the junction.
That’s it, that’s the whole thing. Since your electricity is metered by the current used, you can observe the current flowing through the single junction that supplies all of the power in your home and determine the home’s use. Add it up over a period of time and you know how many units of power to bill for. Now all you need is a way to communicate between the meter and the guy who sends out the bills, and in the old days, that was a “meter reader” who would come out and read the tally off your meter. Now the meters digitally send the reading back to the power company.
Gas meters are the same deal, even easier because you’re measuring the rate of flow of a fluid – you just have the fluid turn a little wheel, and you count the number of times the wheel spins.
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