§ 4 A little theory, a little history ...
From the point of view of "applying the drill rule", the whole variety of meters can be divided into two classes: induction meters and electronic. Single and three-phase, maximum power, the presence of a “stop” that does not allow you to “rewind” the counter, all sorts of “lotions” for multi-tariff metering and remote data transmission, so to speak, “up the authorities” (yes, now such meters also there are) - signs for our "kulibins from the high road" are much less important than the "class essence" of the deceived device. Why? But because each principle of collecting information about power consumption has its own “birthmark”, which gentlemen are electric freeloaders and use. Consider these two classes of devices in more detail.
First class. Electromechanical counters of induction type. A kind of "reptile" of the world of counters: everything around is changing, and as they were born in their Mesozoic, they still live and at the same time feel very well and do not plan extinction. Invented by Galileo Ferraris at the end of the 19th century at the dawn of the proliferation of commercial power networks. Despite the venerable age, and until now they are the main (and in rural areas - and generally the only) type of subscriber means of metering the consumed power. Complex 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 the minimum requirements for staff qualifications and, therefore, the low price), and disadvantages (the impossibility of multi-tariff metering, sensitivity to any influences that disrupt the work of mechanics, inertia, facilitating their "deception").
The principle of operation is the same as that of an induction 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, arrows, mechanical decimal counters ... Due to its simplicity, which you could not help but appreciate from the description, this type of counters provides inexhaustible possibilities for all kinds of "bullying" of any attacker who has mastered the school physics course at least by the four.
Class Two . Electronic counters. If the electromechanical counters are “reptiles”, then this is already a kind of “mammals”, although not even upright, but also a few artiodactyls, sorry for zoology. They are much smarter, smaller, more agile, occupy all technological niches that they can reach, and "evolve" at a fantastic speed.
The first commercial models (still hybrid ones, that is, borrowed a number of nodes from electromechanical forefathers) appeared twenty years ago, and since then at least five generations of their electronic “filling” have been replaced. 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 systems for the commercial accounting of electricity - ASKUE), practically do not require verification, they rarely fail on their own initiative , which is much more resistant to the ill-fated "rule of the 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" constrain: firstly, the price (yes, of course, it drops rapidly, but electromechanics are still cheaper today) and, secondly, non-repairability: the qualifications of the personnel necessary for their repair should be such that often the repair can only be carried out at the manufacturer, and indeed, it will be completely cheaper to replace the entire meter.
How are they arranged and why are they so much more 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 current microprocessors, the task, as they say, is “do not hit the bedridden one”, and the time left from its solution to even the most “slow-witted” representative with a guarantee is enough for both “communicating with higher-level” systems and for displaying information on the indicator, and for other activities he needs. To “trick” them is much more difficult than their predecessors, but, again, as the classics said, “there are no such fortresses yet ...”.