Advantages and disadvantages of electronic electricity meters

In today's world, these devices are indispensable. After all, everyone in the house has electrical wiring, therefore, there must be an electric meter. But here's the problem. As soon as the time comes to replace or, we go to the store and a flurry of variety of choices falls upon us. We start to get lost and end up choosing the wrong thing. To prevent this from happening, let's figure out what counters are, and which one is right for you. Today, there are two main types of meters: induction (mechanical) and electronic.

Induction (mechanical) electricity meters

Fig.1. Induction single-phase electricity meter

Spinning disc counters are familiar to almost everyone. These are the ones that have a spinning wheel behind a transparent panel. Surely, many have watched the speed of its rotation more than once - the higher the speed, the greater the energy consumption. And the counter readings are indicated by numbers on special reels.

Principle of operation such counters is as follows. There are 2 coils in the electric meter (Fig. 2 - 1 and 4 pointers) - a voltage coil (serves as an alternating current limiter, an obstacle to interference, etc., creates a magnetic flux commensurate with the voltage) and a current coil (creates an alternating magnetic flux commensurate with the current ).

Fig.2. The principle of operation of the induction electric meter

The magnetic fluxes created by the coils penetrate the aluminum disc (Fig. 2, pointer 5). In this case, the flows that the current coil creates penetrate the disk several times due to its U-shape. As a result, electromechanical forces appear, which rotate the disk.

Further, the axis of the disk interacts with the counting mechanism in the form of a worm (gear-screw) transmission (Fig. 3), which transmits the necessary signals and information to the digital drums. The higher the torque of the disk, the higher the power of the supplied signal (torque is equivalent to the power of the network), and hence the greater the power consumption.

Fig.3. Worm-gear

When the power of the supplied electromagnetic signal decreases, the permanent braking magnet comes into action (Fig. 2, pointer 3). It evens out fluctuations in the frequency of rotation of the disk due to interaction with vortex flows. The magnet creates an electromechanical force that is inverse to the torsion of the disc. This causes the drive to slow down or stop altogether.

This group of counters is the cheapest and simplest. Induction electricity meters were widely used in Soviet times (and to this day, most of the apartments have just such devices installed). But gradually they are being replaced by electronic meters due to a number of shortcomings of induction devices. For example, an induction electricity meter cannot take readings automatically, and there is often an error in the readings.

Advantages and disadvantages of induction meters

Advantages

1. Reliable in use
2. Many years of operation of the meter
3. Independence from power fluctuations
4. Cheaper than electronic

Flaws

1. The accuracy class is quite low - 2.0; 2.5
2. Virtually no protection against theft of electrical energy
3. High own current consumption
4. At low loads, the error increases (the lower the accuracy class, the greater the error)
5. When accounting for several types of electricity (active and reactive), it becomes necessary to use several energy meters
6. Energy accounting is carried out in one direction
7. Large dimensions of devices

Electronic electricity meters

Fig.4. Electronic electricity meter

These devices are somewhat more expensive than induction, but today they are the most profitable and priority meters to use. They have a higher accuracy class and allow you to take into account multi-tariff.

Electronic electricity meters work by converting the input analog signal from the current sensor into a digital code equivalent to the power consumption. This code is sent to be decrypted to a special microcontroller. After that, the amount of electricity consumed is displayed on the display (or digital drum).

The most important component of these counters is the microcontroller. It is he who analyzes the signal and calculates the amount of electricity consumed. It also transmits information to the output, electromechanical devices and the display.

Fig.5. The principle of operation of an electronic electricity meter

The device itself consists of a housing, a current transformer, a signal converter and a billing module. If we disassemble in more detail, the counter also includes:

• LCD display (or digital drum)
• secondary power supply (converts alternating voltage)
• microcontroller (calculates input pulses, calculates consumed electricity, exchanges data with other nodes and meter circuits)
• converter (converts an analog signal to a digital one and then converts it into a pulse signal equivalent to the consumed energy)
• supervisor (generates a reset signal during power failures, outputs an alarm when the input voltage drops)
• memory (stores electricity data)
• telemetry output (receives a pulse signal about energy consumption)
• real time clock (counts the current time and date)
• optical port (reads the meter readings and also programs it)

Advantages and disadvantages of electronic electricity meters

Advantages

1. Accuracy class - from 1.0 - high
2. Multitariff (from 2)
3. One meter is enough when accounting for several types of electrical energy
4. Energy accounting is carried out in 2 directions
5. Measure the quality and volume of power
6. Store electricity metering data
7. Data is easily accessible
8. In case of theft of electricity, unauthorized access is detected
9. Possibility to take readings remotely
10. Can be used for automated technical metering and control of electricity metering (ASTUE and ASKUE)
11. Long term metrological interval (LMI)
12. Small in size

Flaws

1. Very sensitive to voltage fluctuations
2. More expensive than induction
3. Quite difficult to repair

Marking on electricity meters

In addition to the types of counters, there are a few more nuances that you should be aware of. On any electric meter there is a certain marking, conditionally indicated by letters and numbers.

Fig.6. Designations on the electric meter

Designation	Explanation
WITH	Device type (meter)
A, R	Type of metered energy (active energy/reactive energy)
ABOUT	Single phase meter
3, 4	Number of phase wires in the network (four-wire / three-wire)
At	Versatility
AND	Type of measuring system (induction counter). Next may be three-digit number, which means the design of the meter (the design of the meter can be induction or electronic).
T	Tropical meter type
P, M	Execution type (straight-through - if there is no connection to the transformer / modernized). Further abbreviations may be "380/220 17A, 2001", which means the operating voltages in the wires, the maximum current flow and the year of manufacture. Also at the end of the inscription may be factory number.

As for the accuracy class of the electric meter, these parameters determine the accuracy of the readings of the consumed electricity. In apartments, as a rule, class 2.0 meters are installed, but they can be higher. What does this mean? And the fact that your electricity meter can take into account 2% more or less electricity from its own capacity. Or, more simply, the error of the counter. The smaller the number, the smaller the error. In general, in domestic conditions, a class 2.0 electric meter is sufficient. Higher accuracy classes are more likely to be needed in plants where more power is needed.

So, today we can not limit ourselves in the choice of electric meters. Each of them has its own specific features and functions. In this article, we have analyzed the main features of these devices and the principles of their operation, which will help you navigate the variety of choices.