Electricity meters are multifunctional devices for metering, consumption and saving information on electricity consumption. Until recently, electric meters were fairly simple devices of the induction type of action with one tariff accounting, but with the advent of the micro element base in the modern world, the meters rapidly evolved, divided into many classes and functional capabilities.

The classification of electricity meters, the main characteristics

1. Electricity meters are divided into induction and electronic
   • Induction Counters   -called so due to the effect of magnetic induction, which drives the magnetic circuit and the reporting device of the meter, under the action of the flowing current. Features: weak protection against theft, increased own consumption, limited add. functions, low accuracy class.
   • Electronic electricity meters   - devices with a shunt as a current sensor (overwhelmingly) and a microcircuit of the board for analyzing the readings and outputting them to the reporting device. Features - high accuracy class, many tariff accounting and saving of information on consumption are possible.
2. By the type of network the meter is connected to
   • Single phase electricity meters   used in two-wire single-phase networks.
   • Three Phase Electricity Meters   used in three-phase networks, possibly as three-wire, and four-wire connection.
3. Connection method. Electricity meters are connected either directly to the measured network, in this case the connection is called "direct", or through a measuring transformer - "transformer connection"
4. By the number of measured tariffs, the counters are divided into many tariff and one tariff. Many tariff accounting system - is the calculation of the amount of energy consumed at different times of day, days of the week, due to the different cost of electricity during the day. By default, many tariff electricity meters are programmed for the day-night tariff according to the change in the tariff schedule in your area.
5. Type of tariff meter for multi-tariff electricity meters: with internal and external tariff meters
   • With external tariff - switching takes place under the action of an external signal from an external tariffiser (separately purchased device) or the signal is transmitted through communication channels if the electric meter is included in the AMR system
   • Internal Calculator -   the device included in the device of the electric meter. Of the shortcomings, the need for manual reprogramming of each meter when changing the tariff schedule in the region.
6. By maximum, base, starting measured current
   • Starting current   -the value with which the registration of electricity meters begins
   • Maximum current- the maximum current value at which the correct registration of the consumed current occurs.
   • Base current   - the value of the current, which is the source for setting the requirements for the meter with direct connection.
7. By accuracy class - the measurement error relative to the measurement range. With an accuracy class of 1 and a maximum current of 60A, the maximum error is 0.6A. Currently, most household electricity meters have an accuracy class of 1.0.
8. By types of communication interfaces, communication interfaces
   • Telemetry (pulse)   - transmission of pulses via a two-wire communication line in proportion to the electricity consumed.
   • Optoport (IR)   port - data transmission through infrared communication.
   • RS 485   half duplex multipoint serial data interface. Data transmission is carried out on one pair of conductors using differential signals.
   • RS-232   - RS-232 serial network interface for data exchange with meters. The data transmission range is several tens of meters. The default is built into most computers. Additional lines are required.
   • Fiber optic   - fiber-optic communication line for one-way transmission of meter measurement data. Additional lines are required.
   • CAN- (English Controller Area Network - a network of controllers) is an industrial network standard, focused primarily on the integration into a single network of various actuators and sensors.
   • Plcmodem - Power Line Communications (PLC) is a modern telecommunications technology that uses the power grid for high-speed data exchange. In this technology, based on the frequency division of the signal, the high-speed data stream is divided into several low-speed ones, each of which is transmitted on a separate frequency and then combined into one signal. Thus, a conventional power grid is used simultaneously to transmit electricity and exchange data without reduce the basic functions. Data transmission distance up to 1 km
   • GSM   - cellular interface. Allows you to remotely read information from the counters on the lines of cellular operators. No need to lay additional lines. currently, GSM modems mainly use type counters

This article presents the general principles for the selection of electricity meters and the characteristics on which to focus.

Selection of single-phase electricity meters.

  1. One tariff or multi tariff meter?

A lot of the tariff system of electricity metering was introduced to align the peaks of electricity consumption. In particular, the two electricity tariff metering system was implemented, which should motivate the population to use electricity at night when possible, reducing day-to-day consumption. At night, with two-tariff accounting, electricity costs less than during the day, depending on the severity of this problem in each region, price differentiation is different. Currently, the cost of 1 kW in the daytime in St. Petersburg is 2 rubles, at night, 1.3 for the population. At the same time, the cost of 1 kW for one tariff metering is 1.7 rubles. In this regard, when you purchase a meter with a double charge meter, you will be able to pay less money for electricity if you try to consume some of the electricity at night. For example: you have warm floors in your house, you are often heated in winter with electric heaters, you have a heater, an electric fireplace, etc .., then it becomes reasonable from a financial point of view to purchase two tariff meters. On the other hand, single tariff meters are usually more durable compared to two tariff meters (especially if you have a mechanical reporting device, as in most cases the electronic two tariff meters fail the LCD screen, the set date and time are lost).

2. Rated current of the electric meter.

When choosing, it is necessary to understand the maximum current consumption in your apartment, most of the meters are currently manufactured at a maximum current of 50-60A, if your supplied power is less than 15 kW, this is enough for you. In case the supplied power is more than 15 kW, then we recommend purchasing a 100A meter. To determine the maximum current supplied to your apartment, it is enough to go up and see the rated current of the input circuit breaker. You should not take an electric meter with a current margin, for example, you have an introductory automat on 40A, and you decided just in case you decided to put the meter on 100A. In this case, the electrical household company, begins to suspect that you want to quietly connect more than the allowed power, and force you to change the meter to a rated current of 60A.

3. Case type.

Cases of electricity meters are mainly divided into installation in modular distribution boxes or in switchboards with mounting panel or switchboards SHURN Meters for mounting in modular switchboards, ESR 55, FBU 11205. The counter for installation on the ESR 55 412 mounting panel

4. Availability of communication interfaces for electricity meters

At the moment, there is a phased embedding of electrical equipment in a single system. In the near future, a system will be built that will unite all recording household appliances (electricity meters, gas and water meters) with local dispatch centers. It will be difficult enough to predict how this will happen, whether this information will be transmitted directly through power circuits (PLS modems), through radio communications (GSM modems), the future will show. In principle, for single-phase electricity meters, this question can not be asked. LCD screen is the best interface for many years.

5. Series, model and manufacturer

When choosing a series firstly, you need to check with your sales company which series and which counters are currently allowed in your city (the list is usually listed on the website of the power supply company in your city). From this list you have the right to choose any model you like and install it in your home. Often, representatives of the power supply company recommend a specific counter model for the following reasons:

1. This is a really high-quality counter.
2. This meter is available from an energy sales company, and they expect you to purchase it from them.
3. At this electric meter, the power sales company has good price conditions at the producers.
4. Quality of electricity meters

In principle, at the present moment, it is rather difficult to advise any manufacturer, 80% of Russian electricity meters are produced in the “industrious” district of Changjn. This circumstance is explained by constant price competition between manufacturers, as a result of which it becomes necessary to withdraw production capacities abroad to reduce the cost of electricity meters.

The range of our company includes electric meters produced by LEMZ, INCOTEX, Energomera, MZEP, Taypit, ABB. If the electric meters manufactured by Incotex, MZEP, ABB fail during the warranty period, we will refund the money or change it to a new meter. (since there are very few returns according to manufacturers). If your Energomera meter, LEMZ breaks down, we will offer you to contact the manufacturer for a warranty. When buying all buyers, we honestly warn about this. We cannot advise any particular model, we do not have test benches and professional QCD engineers.

The choice of three-phase electricity meters.

It is much simpler to choose the three-phase electric meter, in comparison with single-phase. In most cases, you are simply notified of which specific model you need to install. And re-negotiate for another model is quite difficult, even if the counter with such requirements is not needed. For example, in the resort area, many owners of private houses are forced to install PO meters. It is quite expensive (9500 with VAT) and a complex counter. Installing it to account for electricity in homes, in our opinion, is the same as riding a tank on a tank. But this meter has power relays, so homeowners in the Kurortny district meekly buy meters, program, install.

The main features of three-phase electricity meters:

• Having a power profile - tracking and memorizing power peaks for the reporting period, broken down by period. Record and save load peaks at a specified time interval. Mostly established in commercial organizations.
• Communication interfaces for data transfer to a communication center or data transfer to a PC. RS485, GSM modem, CLN. Increasingly, data is used as a communication interface for data transmission over a distance.

The most frequently ordered three-phase electricity meters.

• to commercial premises Mercury 230 ART PQRSIDN (availability of power profile, active and reactive energy metering, RS485 interface, internal tariff.)
• and Mercury 230 ART 01 CN for residential use.

Well, the premium counter manufactured by ABB DFB 13205 108 is installed in the cottages. Keeps records of active and reactive energy, has an internal tariff, the rated current 80A, is installed in the modular switchboards, has a small size and a modern design.

Electricity is required in accounting. This task is assigned to electricity meters. Electrical energy is measured in kilowatt-hours - this means that an electrical device that has a power consumption of 1000W is required to work one hour to spend 1 kW / h.

Today's glut of various electronic (and not only) products, a variety of different models and types of electronic meters will be able to enter into the stupor of the ordinary consumer.

The counters in the domestic market are different - electronic (digital), simple mechanical, combined, simply “screwed” and interplanetary are very accurate.

The functionality of today's counters   It is also impressive - in addition to a simple measurement of the power of electricity, the meters can read the tariffs for energy and environmental characteristics, monitor the quality of energy, and allow remote access.

In this article, consisting of several parts, we will try to answer a number of questions that appear when choosing, connecting and working principle of an electric meter.

Since we do not plan to consider this topic very deeply, some questions may not be touched. Therefore, it will not be superfluous to read in ПУЭ7, Chapter 1.5 - “Accounting for Electric Energy”.

To review the topic, we first need to somehow divide all electricity meters into groups according to their different characteristics. In other words, you need to deal with the classification of electric meters.

Separate by different indicators.

By way of work   (constructive implementation):

• Electric.
• Induction.

By power:

• Three phase.
• Single phase.

Wherein three-phase electric meters are divided into:

• By the type of communication interface (for electric meters).
• By type of measured power - active and reactive power meters.
• By the type of connection to the network - transformer or live connection.
• According to the accuracy class.
• By the size of tariffs - single and multi-tariff.

Differences in type of electricity network

The main difference of electricity meters is in the third paragraph, and more precisely, for which electrical network they are intended - for a single or three-phase network.

Single-phase electric meters are used in single-phase two-wire networks with voltage 0,40 / 0,23 kW. Their main use is to account for the consumption of electric energy in apartments or individual houses.

Electric meters for a voltage of 220 (or 127) W, rated current - 5-60 Amps are produced. They are placed at the entrance or installed in interfloor (apartment) panels.

Three-phase electric meters are used for three-phase three- or four-wire networks.

And if everything is simple and clear with single-phase ones, then three-phase devices require a detailed description, as they are used in electronic installations that operate on three-phase currents.

Three-phase electric meters of direct connection are connected to the network directly, without auxiliary devices - current transformers.

Rated current produced by direct connection electricity meters - 5-100 Ampere.

Accounting for electricity consumed is determined by subtracting the original reading of the electric meter (Mon.) from the final reading (Pk.):

But there are cases when the electrical installation consumes a very large current and the electric meter of direct connection cannot pass this current through itself. Therefore, in these cases, the connection of electric meters using measuring current transformers (CT) is used.

The main purpose of the TT. - reduce the current to such indicators at which the device will work normally.

The calculation of the electricity consumed here is also determined by subtracting the initial readings from the final ones and, in addition, by multiplying the resulting data difference by the transformation ratio (Kt.) Of the transformer current:

E = (Pk. - Mon.) X Ct

It is possible to find out the transformation ratio of TT.

For example, the inscription 200/10 on the TT indicates that the initial winding of this transformer is designed for a current of 200 A, and the secondary winding for 10 A.

From this ratio, we have a transformation ratio, which is equal to 20. In other words - TT reduces the primary electric current by 20 times.

Design feature of electricity meters

According to the design, or in other words, according to the type of measuring system, electricity meters are divided into induction and electrical. That is, the device of an electric meter can be both quite simple and quite complex - in the case of an electric meter.

Induction Counter   - the method of its operation is based on the action of the magnetic field of the coils, through the wiring of which current flows, to the rotating part - the disk.

The rotation of the disk we see in the plastic window of the electric meter. Moreover, the number of revolutions of the disk is proportional to the energy expended. These electricity meters have a low price, as well as a fairly high reliability and quality.

Among the shortcomings can be identified:

• Low functionality.
• Low accuracy class (large error).
• Poor (almost no) protection against theft of electricity.

Electronic meter - modern metering device

Despite the large (as opposed to mechanical electricity meters) price, these meters have excellent technical characteristics and good service options.

Features:

• Durable, no rotating parts.
• The increased class of accuracy of electric meters.
• Ability to install a lot of tariff accounting system.
• Increased inspection interval.
• There is an internal memory for saving information on the energy consumed.
• The possibility of an automated accounting system consumed electricity (AMR).

The meter works by switching active power to a sequence of pulses, counted by the installed microcontroller. Moreover, the number of pulses is proportional to the expended (measured) energy.

Electric meter accuracy class

It's er about the accuracy of the measurements. If to say more correctly - the largest possible relative error, which is indicated in percentage.

Today, outdated electricity meters are being replaced with more modern devices everywhere. For a start, this is due precisely to the poor accuracy class of old electric meters, and with increased electrical loads. Therefore, all electric meters with an accuracy class of 2.5 must be replaced with electric meters with an accuracy class of 2 (or 1). All such measures are specified by the Decree of the Russian Federation No. 442.