Three-phase voltage control relay - purpose, installation and configuration. Three-phase voltage relay Three-phase network controller

The phase voltage control relay allows you to instantly turn off the electricity after the meter in the event of an emergency - a power surge in the network. This device is used in both single-phase and three-phase electrical networks to protect electricity consumers from failure. Next, we will look at typical wiring diagrams for voltage relays in an apartment panel.

So, the simplest wiring diagram from the input circuit breaker in the apartment to the voltage control relay looks like this:

In this case, the network is single-phase (220 Volts) and the load is no more than 7 kW, so there is no additional need to connect it to a DIN rail. If the load is more than 7 kW, it is recommended to connect via a starter, as shown in the second diagram for connecting the RN-113 relay:

We immediately draw your attention to the fact that in addition to the distribution panel there must be an RCD or a circuit breaker in order to protect the residents of the house from leakage currents that can cause. The schematic diagram for connecting a voltage relay and an RCD (or a difavtomat) looks something like this:

If you have a three-phase 380-volt network in your private home, the protective device can be connected according to one of two schemes:

The first is recommended to be used if there are no three-phase consumers in the house - a powerful electric stove or 380 V boiler. If you use 3-phase electric motors, you need to protect them with an appropriate voltage relay, for example, RNPP-311 or RKN 3-14 -08, the diagrams of which we provide you with:

Correctly connecting the device to the network

Using a cross module

As you can see, both options additionally have a magnetic starter, which allows you to switch high loads (over 7 kW). In addition, the starter allows you to remotely control the protection, which makes this voltage relay connection diagram very convenient!

Modern electrics in a house or apartment present a wide variety of technical means that require control over the voltage supply. Power management produces a three-phase voltage relay that closes or opens electrical circuits in the event of emergency situations.

Purpose of the voltage relay

Most protective devices contain electronic control relays. If the controlled parameters deviate beyond the specified limits, they are triggered, turning off the circuits. All relays consist of three elements. The first of them is the perceiver. It transmits the value of the controlled quantity to the intermediate element, where it is compared with standard indicators. In case of deviations, the signal is transmitted to the actuator, which turns off the power.

Voltage surges during the supply of electricity, as well as breaks in the power supply circuit, can cause failure of consumer devices. In worn-out electrical networks, phases may stick together or the neutral wire may burn out, which leads to voltage imbalances from 0 to 380 V. In this case, all connected household electrical appliances that do not have protection can be damaged.

Three-phase is used to instantly respond to an increase in voltage above the permissible level and open the electrical circuit. The phase is switched off when a magnetic flux occurs in the electromagnet when current passes through the winding. Using an electronic circuit, the relay is adjusted to certain voltage limit values, when exceeded, the electrical contacts in the load circuit are opened.

The voltage relay is installed in the apartment electrical panel, but there are models that are plugged into an outlet. With their help, the lower and upper limits of the voltage change are selected. It is convenient to set the range to 180-245 V, and then further configure it so that the number of operations is no more than one per month. When the voltage in the network is constantly increased or decreased, it is advisable to install a stabilizer.

The connection of a three-phase voltage relay must be done after the input circuit breaker, the rating of which is selected one step smaller, for example, in the ratio of 32 A and 40 A.

A three-phase voltage relay is connected to current-carrying wires and the network, as well as to the output contacts of the load connection to monitor their condition. Changing modes is done by switching jumpers on the relay terminals. When triggered, its coil is de-energized and opens the power contacts. The winding of a power contactor can be connected to them, which also operates, disconnecting consumers. After a time delay, when the voltage is restored again, the relay returns to its original state, closing its power contacts.

The above scheme disconnects consumers when there is a problem in the network. Protection can also be built on 3 single-phase independent voltage relays. It is used for separate loads on each supply current-carrying wire. Power contactors are usually not used here if the load is not higher than 7 kW. The advantage of this method is that the voltage is maintained in the remaining phases when one of them is turned off.

Features of common types of voltage relays

The devices differ in function and quality. Depending on who and for what purposes you need such devices, they are selected and installed. Next, we will consider the most popular devices.

Relay RNPP-311

The device protects the network in the following emergencies:

voltage exceeding the set values;
short circuit or phase rotation violation;
imbalance or phase breaks.

The device also monitors other network parameters and disconnects the power supply to the load if they deviate from the norm. The three-phase voltage relay RNPP-311 can be configured for two control modes.

On the front panel there are indicators for voltage presence, load connection and some abnormalities. Adjustment is made using six potentiometers. The following parameters are set:

limit values of maximum and minimum voltages, as well as the limit value of phase imbalance;
Load shedding time delay in case of accidents;
delay in connecting to the network after the parameters are restored.

The device remains operational when zero and one of the phases or at least two remain active.

Relay RKN-3-15-08

The device is used for the following control methods:

The response thresholds are set by two potentiometers. The indication allows you to monitor voltage, network errors and built-in operation. Operating conditions are normal.

The connection diagram for the three-phase voltage relay RKN-3-15-08 is practically no different from that shown earlier. It just has a simpler setup. The price for this three-phase voltage relay is slightly lower than for RNPP-311. It is about 1500 rubles. Various modifications of both types can vary significantly in cost, it all depends on functionality.

ASP series devices

In a separate row are the fully digital protective relays of the ASP series. In most of them, it is no longer possible to find tuning elements. Potentiometers depend on the influence of the external environment, quickly age, ratings change, and contact often disappears.

Digital devices do not contain contact mechanical parts, due to which the effect of external factors is reduced and their reliability increases. In appearance, the devices differ in their digital display. Their prices are on average higher, but you can also find budget items.

Relay ASP-3RMT

The model is basic, and it has all the most necessary functions that a three-phase voltage relay should have. Its price is 2 times lower than other devices with built-in digital voltmeters and screens. If a display is not required, but protection is needed, the device is quite suitable for installation.

Relay ASP-3RVN

A three-phase voltage and phase control relay with a microprocessor is used to control the supply of electricity to refrigerators, air conditioners, compressors and other devices. The device is convenient in that it allows you to control the voltage in each phase on the display, as well as monitor its asymmetry. Built-in memory powered by an independent source makes it possible to remember parameters and the number of emergency shutdowns with the ability to display them on the screen. This does not require special setup skills. Additional functions are available via control buttons.

The ASP-3RVN device is connected to the network in parallel with the load, similar to the diagrams presented earlier. The device monitors the current network voltage. In the event of an accident, its contacts connected to the break in the starter winding open. After connecting and applying power, the protection relay checks for the presence of voltage. This is indicated by three LEDs. If there is a violation of phase rotation or adhesion, dashes (--) are displayed on the indicator. Next, the measured phase voltages are displayed on the screen at intervals of several seconds. At the same time, the corresponding LEDs light up.

In the event of an accident, the reasons for its occurrence are displayed on the screen. The settings are initially factory default, but they can be changed by pressing the corresponding buttons. If errors appear during installation, they can be reset and set back to factory defaults with one click of a button. All settings are saved in memory and can be checked.

ABB monitoring relay

One of the well-known devices for protecting electrical equipment is the ABB three-phase voltage relay. The device has proven itself to be one of the most reliable in case of voltage imbalance. For three-phase networks, an ABB SQZ3 device has been developed that can withstand voltages up to 400 V. A large assortment allows you to choose the appropriate model for certain operating conditions. The device allows you to control:

Conclusion

A three-phase voltage control relay is a necessary part of the power supply system to devices. It will reliably protect the electrical network of an apartment or house, as well as expensive electronics from voltage surges and imbalances.

In this publication we will look at how to protect yourself from voltage drops and surges in three-phase electrical networks 380V.

I have already discussed in detail how voltage drops affect electrical wiring and the devices connected to it. Let me remind you briefly.

Increasing the voltage above the permissible level leads to failure of household appliances - they simply burn out.

Reducing the voltage below the permissible level is dangerous for household appliances with electric motors, since inrush currents increase, which can lead to damage to their windings.

Therefore, in order to protect electrical wiring and electrical appliances connected to it, voltage control relays are used, which are also called overvoltage relays, “barriers” or maximum and minimum voltage relays.

These relays monitor the current voltage value in the electrical network and, if it goes beyond the established range, disconnect the external supply electrical network from the internal network, protecting the internal electrical wiring itself and the electrical appliances connected to it.

In this article we will look at two different schemes and two different options for using voltage relays in three-phase 380V electrical networks using the DigiTOP voltage relay as an example.

The purpose of this article is to show a schematic solution for protection against voltage surges in three-phase electrical networks. You can use relays from other manufacturers, the principle remains the same.

I discussed in detail the operating principle of the voltage relay itself and the circuit in the article on. You can download detailed instructions for the relay itself on the Internet; here I will briefly remind you that the relay has two settings:

— the first when the voltage exceeds the maximum value, by default 250V;
— second setting when the voltage drops below 170V (default).

These parameters are set on the front panel of the relay itself using buttons.

When the voltage goes beyond this range, the relay opens its power contact and disconnects the external electrical network from the internal one.

You can also set a delay time for reconnection. After the relay has turned off, the relay circuitry monitors the voltage value, and when it returns to the operating range, after a time delay, the relay again closes its power contact and connects the external electrical network to the internal one.

In those apartments and houses where the electrical wiring is three-phase, single-phase consumers are still mainly used - ordinary household appliances and appliances.

Consumers by phases, so that, if possible, there is a uniform load on each phase.

Let's look at all this with a specific example.

Three-phase voltage is supplied through the input circuit breaker, a three-phase electric energy meter to the electrical wiring of the apartment.

Consumers are grouped into each of the three phases as follows:

— an electric stove is connected to the first phase LA;
— the second phase LB is connected to an air conditioner, a washing machine and sockets in one of the rooms;
— the third phase of LC is connected to the kitchen sockets, sockets of another room and lighting.

To ensure that when the voltage goes beyond its permissible values when the voltage control is triggered, the entire apartment is not immediately de-energized, instead of one common one, three separate voltage relays are installed in each phase.

If in one of the phases the voltage goes beyond its operating range, the corresponding relay will operate and turn off the internal wiring only in this phase. In the remaining phases, if the voltage value is within the specified range, consumers will remain connected and operational.

For detailed step-by-step operation of this scheme, see the video at the bottom of this article.

In the case of connecting three-phase consumers, a slightly different circuit design is used.

For this, a special three-phase voltage relay is used, which allows you to control the voltage in each individual phase, the phase sequence and phase imbalance control.

The connection diagram in this case will look like this.

All three phases are connected to the voltage relay so that the relay controller controls the voltage separately for each phase, the correct phase rotation and phase imbalance control.

Contactor K1 is connected through the power contacts of the voltage control relay. One end of the contactor winding is connected to the neutral wire, the second is connected to one of the phases through the power contacts of the relay. In our diagram to phase LA.

Power normally open contacts K1.1, K1.2, K1.3 of the contactor connect an external three-phase electrical network to a three-phase load. These can be electric motors, powerful heaters, instantaneous water heaters, etc.

The voltage relay monitors the level of effective voltages in all three phases and, if they are within tolerance, then power is supplied to K1 through the power contact of the relay. The contactors of the contactor are in the closed state and the three-phase voltage of the external network is supplied to the load.

If in one of the phases the voltage goes beyond the set range, the voltage relay opens its power contact, removing power from the winding of contactor K1. The contactor contacts open, disconnecting the load from the external three-phase network.

When the voltage returns to its operating range, the voltage relay, after a time delay, will again close its power contact, supplying power to the contactor winding.

The contactor contacts will close and the load will be connected to the mains again.

This is how this scheme works. This scheme is rarely used in everyday life; it is more of an industrial option; the first scheme is most often used.

In more detail, watch the operation of these circuits step by step in the video:

Voltage control relay. Protection against voltage surges in three-phase networks

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To protect expensive household or electrical appliances from power surges, which could lead to their breakdown, a voltage control relay is used. This device provides the rated mains voltage. We’ll talk about the design and connection features of the voltage control relay below.

Design and principle of operation of a voltage control relay

The operating principle of a voltage control relay is to prevent overvoltage or undervoltage of the electrical network.

In answer to the question why you should install a voltage control relay, we will highlight several reasons:

during an overhead line break in the private sector, a voltage surge of 160 W more than usual is possible, as a result of which some easily vulnerable electrical appliances easily burn out and require repair;
in bad weather or for other reasons, a break in the neutral wire leads to increased load and damage to electrical equipment;
when the house is located far from the transformer, the voltage drops to a critically low level, this also negatively affects the operation of electrical equipment;
When a powerful consumer of electricity is turned on, the phase is overloaded, and as a result, due to a lack of voltage, equipment may break down.

The relay consists of a microcircuit that controls its operation. The microcircuit detects a decrease or increase in voltage, transmits a signal to an electromagnetic relay, and the device is instantly turned on, which equalizes the voltage.

The operating range of the voltage control relay is from 100 to 400 W. During a thunderstorm, lightning discharges exceed these indicators, so it is not recommended to rely on a voltage control relay and turn on electrical appliances in bad weather. For such purposes, there are voltage limiters.

The voltage control relay consists of two parts:

electronic,
power.

The first part controls the voltage, and the second part performs load distribution actions.

The main part of the relay is the microprocessor or compactor. A microprocessor based relay is the best as it can smoothly regulate voltage changes.

The main property of voltage control relays is fast action and response. The response threshold depends on the potentiometer setting.

Voltage control relays differ from stabilizers in their operating principle. During voltage surges, the relay turns off those areas where the voltage does not reach normal. Stabilizers - regulate and distribute voltage evenly throughout the network.

Therefore, during emergency situations, it is more effective to use a voltage control relay, which will turn off emergency areas.

Scope of use and advantages of voltage monitoring relays

To avoid overloading of electrical appliances, such as a refrigerator, boiler, boiler, during a decrease or increase in voltage in the electrical network, a voltage control relay is used.

The voltage control relay has a wide range of uses, since electrical appliances are present almost everywhere, then a voltage control relay is necessary in any establishment.

Scope of use of voltage monitoring relays:

protection of single-phase or three-phase networks;
protection against breakage, sticking, phase imbalance;
prevention of violation of sequential operation of phases;
protection of electrical equipment from breakdowns;
use in the protection of devices that have long-term transient operation;
when using devices with a load on an electric motor;
special installations requiring high-quality voltage and the presence of full phases;
used to protect household and electrical appliances from overvoltage in residential buildings and apartments;
used in public institutions: schools, supermarkets, electronics stores, computer rooms, hospitals, cinemas, to protect expensive equipment from damage;
in industrial establishments in factories and factories, to prevent equipment failure.

Advantages of using a voltage monitoring relay:

high operating temperature range from -20 to +40, allows the devices to be used both outdoors and indoors;
the variety of types of these devices allows you to choose a voltage control relay in relation to material preferences;
voltage control relay provides reliable protection of expensive equipment from over- or under-voltage and prevents its breakdown;
a wide selection of models and manufacturers of voltage control relays opens up many opportunities for the buyer to satisfy individual requests;
ease of installation allows you to install this device yourself, without the help of an electrician;
modern models are distinguished by the presence of an original design that easily fits into the overall interior of the room;
during power surges there is no increase or decrease in light intensity;
The device automatically turns off sections of the electrical network that are damaged in the event of an accident or bad weather.

Types of phase and voltage control relays

Depending on the type of connection, relays are distinguished:

fork-socket shape;
in the form of an extension;
rail mounted.

1. The first type of voltage relay is distinguished by the presence of a plug, which facilitates its installation. Such a device simply needs to be plugged into an outlet. It only protects certain groups of consumers. The device is controlled by a microcontroller. It analyzes the current supply voltage and then displays this value on a digital screen. An electromagnetic relay regulates and turns off the load. Such devices have buttons that allow you to turn off and adjust the voltage limits.

2. The voltage control extension relay is similar to the previous type of device. They differ in that the relay extension cord has several sockets and allows simultaneous protection of two or more devices.

3. The relay installed on the D I N rail is mounted directly into the distribution cabinet. Such devices allow you to provide voltage protection for the entire house or apartment. They are distinguished by the presence of additional functions and settings and operate in several modes.

In relation to the type of load, voltage control relays are distinguished:

single-phase,
three-phase.

To protect three-phase motors and equipment, devices of the first type are used. They are designed to protect air conditioners, refrigerators, compressors, and other electrically driven devices.

In a room that provides full-phase control, it is also recommended to use three-phase control relays. If there is a three-phase input in the room, it is possible to install a three-phase voltage control relay, but if one of the phases fails, the remaining two will also be turned off. Even with the slightest surges or phase imbalances, the relay will operate instantly. For example, if the voltage on one phase is 220 W, and on the second 210 W, all phases will be instantly de-energized. Although this voltage is absolutely normal and will not harm most electrical appliances.

Therefore, if there are three phases at the input, it is better to install separate single-phase relays for each individual phase. When choosing the power of a single-phase voltage control relay, it should be taken into account that the device indicates the power that it passes through itself, but does not open. Therefore, you should choose a single-phase control relay several tens of amperes higher than the power of the electrical network.

1. To buy a voltage control relay, contact a specialized store, which will provide a guarantee and advice on the safe use of this device.

2. Voltage control relay price depends on the following factors:

type of device: socket - the cheapest, extension - average cost, rack - rack - more expensive;
manufacturer: domestic relays are cheaper because they do not require payment for transportation, unlike foreign ones;
additional functions - the ability to manually or automatically adjust the power limit of the device;
design - some models have an attractive appearance, are characterized by the presence of several colors, and are, accordingly, more expensive.

3. When choosing a single-phase relay, you should correctly calculate the power of the device. Household relays are characterized by the presence of power contacts whose power does not exceed 100 A. It is recommended to increase the size of the required relay power by 25%, and then, based on the result obtained, select a single-phase type device. For example, if the power of the rated device is 20 A, then the power of the relay required to ensure normal operation of the electrical network will be 35, 30 A.

4. Three-phase relays are easier to choose, since they are all produced with a power of 16 A.

5. When purchasing a relay, be sure to read the operating instructions and ask for a warranty card for the product. Pay attention to the technical characteristics of the device, the material from which the body is made, the maximum and minimum operating temperature.

6. Before installing the relay, you should install an automatic shutdown device that can turn off the power supply if the voltage is higher or lower than the permissible norm.

7. Choose a device with a display that will constantly display the voltage value.

8. When choosing socket voltage control relays, install them on all expensive devices that are equipped with an electric motor.

9. The body material must be non-flammable, the most acceptable option is polycarbonate.

10. Please note that there is a function to control the device’s response time.

11. Additional protection of the device from overheating, measuring the exact value of the power of the electrical network - will allow the voltage control relay to work more efficiently.

Voltage control relay: connection and installation

Before you familiarize yourself with the rules for installing a voltage control relay, let's consider the reasons why you should install this device.

If the power of the electrical network is reduced, for example, if the constant power value in the house is 160-190 W, then a refrigerator, the service life of which is about ten years, will work under such conditions for a maximum of three years. Installing a voltage control relay will not help, since this device will constantly turn off the power supply, and the refrigerator will periodically defrost. In this situation, it is necessary to install a stabilizer. But, if power surges and breaks constantly occur in the electrical network, then installing a voltage control relay is quite appropriate.

To connect the relay you will need:

voltage monitoring relay device,
a small wire with a cross-section of 0.4-0.6 cm,
iron rail for attaching the machine gun,
self-tapping screws,
pliers,
indicator,
screwdrivers.

Before installing the voltage control relay, turn off the power supply. To do this, turn off the input circuit breakers. Install a rail near the location of the machines and secure it to the wall using a screwdriver and self-tapping screws. The relay is fixed to the rail using a special design of latches, which are located at the back.

On the input machine, using the indicator, find the phase (the indicator should light).

Where the phase wire enters the room, it should be cut. One end of the wire should be connected to the relay, to the input contact, and the other end is connected to the output contact.

Turn on the power supply and check the operation of the device.

The socket type voltage control relay circuit is the simplest. After purchase, such a device is simply plugged into an outlet, and the plug of a certain device is already installed in it.

A mandatory element of voltage relay protection is the installation of an input circuit breaker. It is mounted near the machine and the relay itself. The rating of this device is one step less than the relay rating.

When installing a relay whose power exceeds 65 A, an additional starter must be used. To avoid frequent triggering.

This article is a continuation of the article about the device and circuit of the Barrier voltage relay. I described in detail how this wonderful device works, and now I will give an example of its use.

The background is briefly as follows.

My long-time clients approached me - a company that is engaged in vigorous activity on the Internet and advertising business. After their zero burned out, which I already wrote about in the article, they decided not to tempt fate further, but to protect themselves from voltage troubles.

Here is a terrible photo taken from that article:

Burnout of zero from the zero bus. The damage amounted to more than 100 thousand rubles.

This is what I wrote to the client in response to the request:

Technical proposal for modernization of the power supply system

Subscribe! It will be interesting.

To avoid damage to electrical equipment, it is proposed to install an additional circuit based on a voltage relay.

If the voltage goes beyond the permissible limits for various reasons (short circuit on the line, zero break, overload, etc.), the voltage relay will turn off the consumer.

As soon as the voltage returns to nominal, the voltage relay automatically turns on the power.

There are two options:

Option 1

Three-phase voltage relay. Turns off power to all consumers in case of problems in one of the three phases. A power contactor is required.

Option 2

Three independent single-phase voltage relays. In case of problems, it turns off only “its” phase. In this case, power is supplied to consumers of other phases (which are normal) as usual. No power contactor required.

Since all consumers are single-phase, Option 2 is preferable.

Approximate cost breakdown for two options:

Option two with three single-phase relays was chosen, since almost the entire load is single-phase. The exception is the three-phase ventilation panel, which powers a three-phase asynchronous motor. But it was decided not to allow this load through the Barriers.

Device diagram

Here is a diagram of a three-phase voltage control relay assembled on three single-phase Barrier voltage relays:

I emphasize once again that such a scheme is only suitable in cases where three-phase power is supplied to a switchboard from which a single-phase load distributed among the phases is supplied. When the load is three-phase (for example, electric motors), then the use of such a circuit can be dangerous, and option 1 (three-phase relay) must be used. Or change this circuit so that all three phases are turned off at once. To do this, it needs to be supplemented with a contactor, if anyone needs it, I’ll tell you in more detail.

For those who have read my previous articles, there is nothing incomprehensible in this scheme.

However, let me explain.

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As usual, voltage is supplied to the meter through the input switch.

Each relay (A1, A2, A3) operates on its own phase (L1, L2, L3). The relay outputs are the outputs of this circuit; I decided to designate them as R, S, T. Next, the phases arrive normally at their single-pole circuit breakers, and through them they disperse to consumers.

Circuit breakers F1, F2, F3 are not protective and are used simply as bypass switches. They are supposed to always be off, otherwise this whole circuit makes no sense. They turn on as a bypass only in emergency cases when the voltage relay does not work for some reason.

And there can be two reasons for this - relay failure and voltage going beyond the established limits.

However, there is a third reason, which is not mentioned in the instructions, and which I talked about in the previous article - when the voltage limits change, the relay turns off. Therefore, the bypass machine must be turned on when setting up the voltage relay, otherwise the load will be turned off during the setup time.

Entry 1

The customer has 4 inputs for two buildings, they all have differences, I will draw the attention of readers throughout the article.

First input. In the electrical room I saw this picture:

1 – electrical panel

At the top left is a panel with an input switch, a three-pole D80 circuit breaker.

More details about the inside of the shield:

1 – electrical panel interior

Above – Three-phase meter Energomera, digital voltmeter Digitop VM-3, street-generator switch.

Read my article about the different ways to connect a generator. It tells you how to make manual and automatic transfer of reserve (ATR).

Here's a closer look at the first row, it will be very important for us, since all the connections will take place there:

1 – Counter outputs to switch

On the switch, at the top left, there are wires (white, blue, brown), into the gap of which we will need to connect our protection relay circuit. This place is even closer:

1 – Counter-generator switch

The flexible wires on the right side of the switch are from the generator, which is installed on the roof of the building.

Despite the fact that this electrical panel was assembled by a reputable company, immediately there is a serious mistake– pay attention to 25 Ampere machines:

1 – Gross mistake in choosing circuit breakers

And if on the right side of the photo a wire with a cross-section of 2.5 mm² can be understood and forgiven, then six wires of 1.5 mm² will no longer fit into any gate. Here I would lower the rating to 13 or 10A, but I need to deal with the load, and that’s not what I came to this facility for. For those interested, I discuss this problem in detail in an article about. There are also many links to relevant articles.

Okay, let's start assembling our circuit, which I put in a separate panel:

The wire for installation was PV1, single-core, with a cross-section of 4 mm². Or rather, VVG4x4 dissolved into sinews. I connected it into the gap through a terminal connection with a screw, I couldn’t take a photo, there will be more examples below.

Here's what we ended up with:

1 – Final view of the three-phase voltage control relay

I printed operating and setup instructions for users on the back of the cover. I will give the text below.

Input 2

Here I photographed the input machine:

2 – Input automatic switch (switch) to the meter

Three-phase input differs fundamentally from single-phase. More details -.

And the electrical panel looked like this:

2 – appearance of the electrical panel

The meter has a magnetic seal. Why it is needed - I refer you to the article about. But I say again - you need to live honestly!

2 – Magnetic seal on a three-phase meter

Appearance of the place where there will be a gap for connecting our voltage control relays:

2 – counter outputs

Closer, we are interested in the upper connection to the switch, on the left:

2 – wires between the meter and the switch, where the three-phase voltage relay will be connected

There's still a voltmeter in the way, but you'll have to leave it.

The process of assembling the second panel with three Barrier voltage control relays is shown:

2 – Three-phase voltage control relay based on Barrier relay

This is how this shield is connected:

2 – Connecting the voltage relay to the gap after the meter

This connection is very important because all power to the office goes through it. Therefore, I made it through screw-type terminal blocks (clamps).

The blue wires that previously went to the switch terminals now go through the terminals to the voltage relay panel. And from the Barrier outputs, the wires are connected directly to the switch terminals.

The connections in the panel are shown in the photo:

2 – Connections in the panel of the three-phase voltage control relay

The input cable carries three phases and zero. The current through the neutral wire is more than 100 times less than through the phase wires, so it can be neglected.

The second output cable uses three cores, the fourth is a spare (reserve).

As a result, the currents in the cables are the same, the cable is used at 75%, which is optimal from the point of view of overheating.

The second electrical panel took this form:

2 – Electrical control room with a new panel

A closer look at our shield:

2 – Panel with three-phase voltage control relay

Entry 3

Below are photos of the assembly and installation of the shield on the third input.

3 – assembly process.

Pay attention to the color sequence of the wires. Question: Which country am I a patriot?

I decided to use a flexible PVS 4x4 cable, because I had suffered in the first previous cases with solid cores. But in this case it is necessary to use tips, because... for screw terminals, which are used in Barriers, the strand is not comme il faut.

3 – Electrical panel assembled and installed

In the previous two versions, the wires went from top to bottom under the DIN rail, which is a little annoying.

Therefore, here I expanded the consciousness and the distance between the phases, and laid wires into the resulting gaps. The fact is that the Barrier block occupies approximately 2.8 modules on the DIN rail, and there will be gaps in any way. So why not use them for convenient installation?

3 – Shield with Barriers installed

3 – General view

Input 4

4 – Appearance of the shield. A three-phase Barrier is connected to the gap through the screw terminal block

Closer. I think everyone understands why I use a terminal strip and do not connect directly to the meter terminals?

4 – Counter output – to terminal block

In previous versions, the panels were external, installed in electrical panels (utility rooms) and there were no installation problems. Immediately I had to make a built-in installation; I needed a drywall hacksaw.

4 – Inserting the shield into a plasterboard wall

4 – Final look

User instructions

As promised, I am posting instructions for the voltage relay, which can be seen in the photo.

I tried to write in simple language what it is, why and how:

Voltage control relay

Designed to automatically switch off the load if the voltage value exceeds the permissible limits. They work on each phase separately.

Automatic machines F1, F2, F3 – bypasses, during normal operation MUST BE TURNED OFF(lower position). They are switched on in emergency cases, under the personal responsibility of the switcher!

Attention! When the bypass is turned on, the load is not protected from dangerous voltages!

During normal operation, voltage relays A1, A2, A3 indicate the voltage value in their phase.
If the voltage goes beyond the set limits, the relays are turned off and the voltage readings flash.
Turning on - approximately 1 minute after the input voltage has normalized.

If you need to change the voltage limits, please refer to the instructions. While setting voltage limits and delay time the bypass circuit breaker must be turned on.

Thank you all for your attention, questions and comments, as always, I’m waiting for you in the comments.