§ 4 A bit of theory, a bit of history ...
From the point of view of the "application of the gimlet rule", the whole variety of counters can be divided into two classes: induction and electronic counters. Single and three-phase, maximum power, the presence of a "stopper" that does not allow "unwind" the counter, all sorts of "gadgets" for multi-tariff metering and remote data transmission, so to speak, "up through instances" (yes, now such counters there are) - signs for our "Kulibins from the high road" are much less important than the "class essence" of the deceived device. Why? And because each principle of retrieving information about the power consumption has its own "birthmarks", which gentlemen and electrohazers use. Consider these two classes of devices in more detail.
Class one. Electromechanical induction type meters. Such "reptiles" of the world of counters: everything changes around, and they both originated in their Mesozoic, and still live today and at the same time feel very good and do not plan extinction. Invented by Galileo Ferraris at the end of the XIX century at the dawn of the spread of commercial electrical grids. Despite the venerable age, and up to the present time are the main (and in rural areas - and generally the only) type of subscriber means of metering the power consumed. Complicated electronic filling is absent in principle, hence the advantages (low sensitivity to all kinds of electrical impulses, the ability to assemble and repair almost "on the knee" with minimal requirements for personnel qualifications and, therefore, low price), and disadvantages (the impossibility of multi-tariff metering, sensitivity to any effects that violate the mechanics, inertia, facilitating their "deception").
The principle of operation is the same as that of an asynchronous electric motor (well, you understand me): the winding system creates a rotating magnetic field that spins the conductive disk placed in it, usually aluminum. Next - all kinds of gears, hands, mechanical decimal counters ... Because of their simplicity, which you could not fail to appreciate from the description, this type of counters provides inexhaustible opportunities for every "attacker" who has mastered a school course of physics at least "four".
Class two . Electronic counters. If electromechanical counters are "reptiles", then these are already a kind of "mammals", although not yet upright, but a few more hoofed ones, sorry for zoology. They are much smarter, smaller, more agile, occupy all the technological niches that they can reach, and "evolve" with fantastic speed.
The first commercial models (still hybrid, that is, borrowing a number of nodes from electromechanical forefathers) appeared about twenty years ago, and since then at least five generations of their electronic “stuffing” have changed. Now such meters do not have moving parts, they are able to take into account electricity at any number of phases and tariffs, "communicate with higher authorities" (work as part of automated commercial electricity metering systems - AMR), practically do not require verification, rarely fail on their own initiative where it is more resistant to the ill-fated "rule gimlet", and more precisely at least an order of magnitude. In a word, there are a lot of advantages ... But there are two drawbacks that their “triumphal procession” is holding back: first, the price (yes, of course, it drops rapidly, but electrician is still cheaper today) and, second, non-repairable: personnel qualifications required for their repair should be such that repair can often be carried out only at the factory, and in general, very often it will be cheaper to replace the meter as a whole.
How are they arranged and why is it so accurate and reliable than their electromechanical counterparts? As you know, power is the product of current and voltage. Fine! We measure the current, measure the voltage, multiply, add to the previously calculated ... And so hundreds or even thousands of times per second. From the point of view of the current microprocessors, the task, as they say, “do not hit a bedridden one”, and the time left from its solution even with the most “thoughtless” representative of them, with a guarantee, is enough for “communicating with higher-level” systems and and for the other classes he needs. It is much more difficult to “deceive” them than their predecessors, but, again, as the classics said, “there are still no such fortresses ...”.