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Machines, Rc Ds, Meters

August 12, 2017 18:07

Typical connection diagrams of three-phase electricity meter

Good day, dear readers Electricians site itself!This article describes the circuit connection of three-phase electricity meter (TC) in the grid and provides tips on installation.We recommend not only to study the provided wiring, but also view the video tutorials, which describes the electrical installation technology and others, important nuance.

  • preliminary stage
  • Direct (direct) inclusion
  • inclusion in the single-phase circuit
  • Connection through current transformers
  • Polukosvennoe
  • Star
  • Indirect

preliminary stage

Connecting electric meter (ES) is the final stage of electrical work.Before you install a three-phase EC must first have a wiring diagram.The device must be checked for the presence of the seals on the screw housing.These seals must be specified year and quarter last check and print verification officer.

When connecting wires to the terminals to make better supply of 70-80 mm.In the future, such a measure would make measurement of power consumption / remounting current and, in the case if the scheme was assembled incorrectly.

Each wire must be clamped in the terminal box with two screws (see photo below them clearly visible).The upper screw is tightened first.Before tightening the lower need to make sure that the top wire is clamped, after tugging on it.If the meter is connected using stranded wire, it must be pre-molded tips.

Mercury TC 231 photos

Figure 1 - Vehicle Mercury 231

will now be considered standard three-phase meter circuit connection to the grid.

Direct (direct) inclusion

This is the simplest installation scheme.With the direct inclusion of the vehicle is included in the network, without measuring transformers (Figure 2).Most often, this mounting method is used in domestic networks for electricity metering, where there are powerful plant with a rated current of 5 to 50 A, depending on the type of the wiring (4 to 100 mm2).Operating voltage is usually 380 V. When connecting the wire to the three-phase meters is necessary to observe the color order: Phase 1 A should be on the wire yellow phase in - on the green, C - on red.N Zero wire should be blue, and the grounding PE - yellow-green.For protection against overload on the entrance are installed machines.

Figure 2 - Direct CU inclusion

network Brief video guide connecting a three-phase meter is shown in this video:

Electrical three-phase model
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inclusion in the single-phase circuit

Before describing this schemeconnect the meter to the network of 380 volts is necessary to give a brief description of the differences between the three-phase voltage of a single phase.In both types of uses one neutral conductor N. The potential difference between each phase conductor and the zero is 220 V, and these phases in relation to each other - 380 V. Such a difference is obtained due to the fact that the oscillations at each wire are shifted by 120 degrees(figures 3 and 4).

voltage fluctuations

Figure 3 - Voltage fluctuations

Figure 4 - Distribution of phases

voltage single-phase voltage is used in private homes, in the country, as well as in garages.In such places, the power consumption is rarely more than 10 kW.It also allows you to use on the site cheaper cables with section 4 mm.kv., t. To. The current consumption is limited to 40 A.

If the power consumption of the network more than 15 kW, the use of 3-phase wiring is required to evenif there are no three-phase consumers, in particular electric motors.In this case, the load is distributed over the phase conductors, thereby reducing the load if the same power from a single phase was sampled.Therefore, in stores and office buildings, generally used is a three-phase power.

Schematic diagram of the connection of three-phase meter in a single-phase network (OS) is not as common as in such cases the single-phase meters.In most cases, direct wiring diagram similar inclusions, but the phases 2 and 3 is not connected (connection occurs on one phase).In addition, after the installation can cause problems with the organizations being checked.

also about possible problems of the work of three-phase electricity meters when attached to a two-wire network, you can look at this video:

Connecting the meter to the network 220 volts
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Connection through current transformers

maximum current of the meter, as a rule, a value of 100 is limited, so their use in high-power electrical impossible.In this case, connection to three-phase network is not directly but through a transformer.It also allows you to extend the range of current and voltage measurement meters.However, the main task of the input transformers - reduce the primary currents and voltages to safe values ​​for ES and protective relays.


When connecting the meter transformer is necessary to follow the polarity of the start and end of the winding of the current transformer, a primary (L1, L2) and secondary (I1, I2).Similarly, care must be taken when using the polarity of the voltage transformer.The general point of the secondary windings of the transformers must be grounded.

Appointment current transformer contact:

  • L1 - phase input (power) line.
  • A2 - exit phase line (load).
  • I1 - the input of the measuring coil.
  • I2 - output measuring winding.
Six-wire circuit connection through CT

Figure 5 - Desyatiprovodnaya circuit connection through CT

This type of inclusion in the electricity network of 380 volts allows you to split the circuit voltage and current, which increases the electrical safety.The downside of this three-phase electric circuit connecting the counter is a large number of wires needed to connect the ES.


This type of connection of the meter to the ground network 380 requires fewer wires.Turning wye is achieved by combining the output of I2 CT windings into a single point and connection to the neutral conductor (Figure 6).

The inclusion of a "star" of transformers

Figure 6 - Enabling Transformers "star»

disadvantage of this method of connecting the electricity network of 380 volts is the darling scheme of compounds that may complicate the inclusion of checks to representatives of utility companies.


This wiring diagram three-phase meter is used on high-voltage accessions.This type of indirect attachment is used in most cases, only in large enterprises and are for guidance only (see Figure 7).

Indirect inclusion

Figure 7 - Indirect inclusion

used in this case not only the high-voltage current transformers and voltage transformers.For three-phase connection, you need to ground the common point current and voltage transformers.In order to minimize the measurement error if there is asymmetry of the phase voltages is necessary to zero the network wire was connected with zero clamp meter.

proposed in the article are typical wiring diagrams.If the need arises, the counter wiring diagram can always be seen in ES passport.We hope that the information was for you interesting and useful!