Arrester oin 1 connection diagram. Surge suppressors in home electrical wiring

A residual current device (RCD) is a device that protects a person from electric shock and also prevents damage to electrical receivers. The principle of operation of the device is simple: it compares the currents in the phase and neutral wires. If they are equal, then the network is operating normally and the device does not respond. As soon as a difference in values appears due to the fact that less current flows through the zero than the phase current, which indicates a leak, then the device immediately (in less than 0.1 sec) operates, disconnecting the power receiver from the network.

Where to place a single-phase RCD

Circuit breakers may not respond to small leakage currents that are dangerous to human health and life, and network grounding, although it protects, will not save the equipment. That's why they install an RCD. A current of 0.1 A is considered fatal to humans.

The RCD response current, i.e. the difference in phase and zero, is 0.03 A.

In everyday life, it is not advisable to use more sensitive RCDs due to the fact that the device can often turn off the voltage for no apparent reason. In order to understand the connection principle, you need to know which wires go to the apartment.

Namely:

From the transformer substation the cable runs to the house or entrance.
The cable contains 3 phase and 1 neutral wire.
Each phase wire has the same number of flats to balance the load.
All this extends to the common access panel, where a grounding wire is also added, discharging part of the current in case of damage to the wire insulation.

The risers on each floor carry phases, a neutral wire and grounding to the distribution panels. The panels are equipped with additional circuit breakers that disconnect the network in the event of a short circuit. From the machines to each apartment there is 1 phase, neutral and ground wire. In the apartment, wiring laid in the wall is connected to each socket and to the lighting outlets.

Installing an RCD in a single-phase network is not difficult. The device has 2 input terminals and 2 outputs. Phase and neutral are placed in the input terminals, respectively, without touching the ground wire. The wires passing through the device exit through the output terminals and are drawn directly to the electrical energy receiver. The device itself should be connected after the automatic shutdown. The devices from ABB have proven themselves to be the most effective.

The device is often equipped with a digital indicator, which serves to visually monitor the voltage level of the connected network. The COICOP09I indicator is often used for these purposes.

Features of RCDs in a two-wire network

A two-wire network implies the presence in the apartment of only a phase and a neutral, without ground. Today, this type of wiring is used only in old Soviet buildings or some private houses.

In a two-wire network, there are several ways to connect an RCD:

Installation of a single powerful device, which, in the event of a malfunction, will turn off all electrical equipment and lighting in the house.
Installation of less powerful devices separately on sockets, or lighting divided by consumption zones (bathroom, kitchen and other sockets in the rooms).
Complex.

Each option has both pros and cons. The first one will cost less, because... 1 device is purchased, but in case of a leak, it will turn off all devices in the house, which will cause discomfort. Determining which equipment caused the outage will be problematic. The option with several protection devices is somewhat more expensive and will take up more space in the distribution panel. This scheme will be more reliable and accurate.

How to connect an RCD without grounding: diagram

Now it’s worth considering some schematic solutions for installing an RCD.

A diagram where the RCD is divided into separate consumption groups (bathroom, kitchen, bedrooms, and sometimes can also be used specifically for lighting) will look like this: the phase and neutral wires after the circuit breaker are divided into power supply for the electricity consumption groups.

Each set of wires (phase-zero) goes to a separate group.

Here they install a separate RCD for each group, passing wires through the input and output terminals. Place separate ABs for each group. The neutral wires of each group are output to the neutral buses.

Connection diagram with a common RCD:

The neutral and phase wires coming out of the common circuit breaker are connected to the input terminals of a powerful 25 A RCD.
From the output terminals, the wires enter the apartment, where they power power-receiving devices designed to be plugged into an outlet.
If one electrical consumer breaks down or there is a wiring fault, all devices will be de-energized.

Sometimes, after the machine, a surge suppressor (SVP) can be installed, protecting wiring and equipment from lightning discharges and induced communication surges. This device is installed between phase or neutral and ground. In this case, the RCD is installed after ONE, providing complete, multi-stage protection not only for humans, but also for electrical appliances and wiring.

Rules for installing an RCD in a private house without grounding

Modern buildings are subject to mandatory grounding. Only old buildings have the old model of power supply and do not have grounding. To avoid accidents. in such areas an RCD is simply necessary. The house can be connected to either 1 or 3 phases. The choice of protection devices depends on the number of phases. An RCD in a private house with one phase can also be installed with options - one RCD, several devices that disconnect different groups.

A private plot is distinguished by the fact that it can have not only a house building, but also:

Garage;
Bath;
Barn.

Each of these buildings represents a separate group of energy consumers, because they contain not only lighting, but also other parts that consume electricity and, sometimes, in large quantities, for example, a pump for pumping water into a pool or heat guns in a barn in winter.

On a private site with one phase, it would be correct to choose a connection diagram from several RCDs and circuit breakers.

If a private house has a three-phase network, then special protection devices are used to protect it. They disconnect one specific phase in case a fault occurs. The remaining phases continue to operate normally. The load must be evenly distributed among the phases to avoid voltage imbalance.

Exact diagram for connecting a three-phase RCD in a single-phase network

This method is not very rational, but, nevertheless, it is sometimes used. This method is used for sequential installation of an initial single-phase network, to which 2 more electrical components are then added for a general protective function.

It is very important in this case that the phase is connected to the current conductor through which the RCD will be tested in operating condition.

To do this, the resistance of each phase and zero is called. In this case, the power contacts must be turned on and the test button must be pressed. It should be noted that this action must be carried out on a dismantled RCD in the absence of voltage.

A three-phase RCD, which is connected to a single-phase network, has 3 circuits:

Phase through Line1 - connection goes to it, and N through N.
The phase through Line1 and Line2 are connected in parallel, and N through N and Line3 will also run in parallel. It is possible to double the current through the RCD.
The phase through Line1 and Line3 is connected in series, and N through Line2 and N is also connected in series. With this connection, the sensitivity of the RCD will increase.

Due to the fact that the contacts will be broken, the resistance at 2 terminals will be equal to infinity. And one will show the resistance value of the resistor, which limits the current. It is to this terminal that you will need to connect.

The surge suppressor is an often underestimated, but very important element. This element is recommended for installation by electrical equipment manufacturers, while opinions are divided among electricians themselves. Let's look into this matter. The most frequently asked questions about the arrester are as follows: What are the classes of arresters? What does it consist of and how does it work? How to connect a surge suppressor? Does it really protect electrical devices?

Limiter protection classes

In the voltage range below 1000 V, limiters are divided into 4 classes, designated by alphabetical letters: A, B, C and D.

Class A limiter is not used in domestic installations, but is used to protect power lines.
Class B tread used to protect against high voltage surges, such as those caused by lightning striking a power line.
Class C limiter Designed for surge protection with slightly lower network voltages. Class B and C protective devices are usually installed in household switchgear.
Class D tread used for direct protection of selected electrical devices that are sensitive to impulse noise and surges in a 220 V network. It is mounted in a distribution panel, behind a socket in an electrical box, or directly in the protected device.

Each protection device limits the electrical potential to only a certain level. The closer the equipment is to class A, the higher the power. For example:

Class A will reduce the voltage level to 6 kV,
Class B will reduce the voltage level to 2.5 kV,
Class C will reduce the voltage level to 1.5 kV,
Class D will reduce the voltage level to 0.8 kV.

Therefore, limiters of individual classes should be used in cascade, gradually reducing the level of the maximum voltage. That is, if there is one switchgear in the house, we use both B and C class protective devices (there are 2 in 1 B + C protective devices).

If the building is multi-storey, class B protective devices should be used in the main distribution panel, and class C limiters should be used in the distribution panels in individual apartments.

If the device connected to the outlet is sensitive to voltage surges, we can also use Class D suppressors. We do not have access to Class A suppressors, this is a concern for the power company.

Since we will be looking at home wiring, the article will focus on class B and class C (types I and II) protective devices.

Designation on circuit diagrams

The main symbols used to designate surge arresters are as follows:

General designation of the arrester
Tubular arrester
Valve and magnetic valve arrester

Installing a surge suppressor

A standard B or C (possibly B+C) arrester consists of two components:

Limiter base
Replaceable insert with protective element

Warp

The base of the protective device is mounted on a TS35 DIN rail. It has two clamps. Connect the phase (L) or neutral (N) wire that may have too much electrical potential. On the other side, connect the PE protective conductor, which is connected to the protective line of the switchgear.

The protective conductor should have a minimum cross-section of 4 mm2, but it wouldn't hurt to go larger. After all, there is a possibility that a very high current will flow.

There are 3 contacts under the PE terminal. As standard, the kit includes a plug that is inserted into the right place and allows you to connect the wires. Thanks to these clips, it is possible to remotely notify in case of damage to the insert or its burnout. This signal can be connected, for example, to the input of the alarm control unit (see diagram). In this case, the control panel will be informed that the insert is damaged by opening the electrical circuit between the red and green wires.

Insert

The insert contains all the most important elements thanks to which the defender functions correctly:

Class B (Type I) - the main element is simply the spark gap.
Class C (type II) - here the varistor part is the main element.

How does a surge protector work?

Protection is provided by devices powered by 220V network cords connected to the arrester in the distribution box. This applies to both phase and neutral conductors (depending on the selected type of protection).

The general rule is to connect the phase conductors and possibly the neutral conductor on one side of the protective device, and the protective conductor on the other side.

When the system voltage is normal, the resistance between the wires is very high, on the order of several GigaOhms. Thanks to this, current does not flow through the arrester.

When a power surge occurs, current begins to flow through the limiter to ground.

In class B protective devices the main element is the spark gap. During normal operation, its resistance is very high. In the case of a spark gap, this resistance is gigantic, since the spark gap is actually an open circuit. When lightning strikes a component of an electrical installation directly, the spark gap resistance drops to almost zero due to the electrical arc. Due to the appearance of a very high electrical potential in the spark gap between the previously separated elements, an electric arc is created.

Due to this, for example, a phase wire in which there is a large voltage surge and a protective wire create a short circuit and a large current flows directly to the ground, bypassing the internal electrical installation. After the discharge, the spark gap returns to its normal state - that is, it breaks the circuit.

Class C limiter has a varistor inside. A varistor is a specific resistor that has a very high resistance at a low electrical potential. If a voltage surge occurs in the system due to a discharge, its resistance quickly decreases causing current to flow to ground and a similar situation as in the case of a spark gap.

The difference between Class B and Class C is that the latter is capable of limiting voltage surges with a lower potential than a direct lightning strike. The disadvantage of this solution is the rather rapid wear of the varistors.

The main thing in surge suppressors, regardless of the class used, is the installation of grounding with very good parameters, that is, with very low electrical resistance. If this resistance is too high, the overvoltage current (caused by a lightning strike) can flow through the electrical system instead of the protector and leave behind burnt equipment that is currently plugged into 220-volt outlets.

Connection diagram of the limiter to the network

How to connect a limiter to a home panel? Let's start with the basics. We have a single-phase network and a single-module arrester. We want to protect the phase wire with it. Network type - TN-S.

We connect the phase power conductor directly to the arrester and connect the arrester on the other side to the PE terminal block.

But this home switch has nothing more than a surge limiter. Let's add the missing elements.

As you can see, installing a surge suppressor does not affect the further organization of components in the home switchboard. The connection of the residual current device and circuit breakers is carried out in the same way.

In general, in switchgears, surge arresters of class B, C or B + C are installed before the circuit breaker (or circuit breakers) and overcurrent fuses. But the limiter is the first element underlying the protection of a house or apartment.

Three-phase installation

In a three-phase circuit, the width of the limiter and the number of protected connections increase. However, the operating principle of the limiter remains unchanged. The most commonly used three-layer system protective devices operate in a 4 + 0 system, which means connecting the following lines to the arrester:

3 phase wires
1 neutral wire

Each of the wires to be protected has equal rights, that is, possible overvoltages are eliminated by supplying current to the protective installation and, as a result, to the ground.

Of course, for TN-C installations (installations without a separate protective conductor) it is possible to purchase protective devices with only 3 protected connectors. Then, from the bottom side, connect the limiter to the PEN (protection neutral) strip.

Safety and effectiveness of the limiter

In domestic installations this is not often practiced because short circuit protection exists in the form of a circuit breaker or fuse and its low current rating safely protects the network from failures.

Surge suppressor parameters

Before you go to the store and buy this device, you need to know the following:

The number of modules (terminals) depends on the type of your network. 1 module can be purchased when there is a single-phase TN-C system. 3 modules when the installation is in a three-phase TN-C network and 4 modules when the network is three-phase in TN-S or TT.
Class (type) - you can choose between classes B, C or B + C. If you are not sure that a type B limiter is used in front of your apartment, you should choose a B + C solution. Otherwise, a type C limiter will be sufficient.
The rated voltage at which the limiter operates.
Uc is the operating voltage of the protector, that is, the maximum voltage level that will lead to operation.
In is the rated current of the limiter, that is, what current can flow through the arrester in the event of a short circuit.
Imax is the current that the arrester is capable of accepting during an atmospheric discharge. Please note that both values (In = 30,000A and Imax = 60,000A) will be relatively large in relation to the current during normal operation of appliances in the house.
Up - the voltage to which it decreases in the event of a rupture. For example, if the potential reaches a voltage of 10,000 V in the event of a surge, the final value drops to 150.

Is it worth using a network limiter?

Every electrician wonders whether it is worth buying a surge arrester at all. After all, this is not the cheapest element of electrical installation. Theoretically, when repairing or building wiring from scratch in an apartment or house, the cost of 3,000 rubles (in the case of a 4-module protector) is a drop in the ocean of expenses. In practice, a protective block will not always have the opportunity to prove that it is needed. Even if it does work, voltage reduction may not always protect sensitive electronic devices (class D protection is better).

Here I present several typical connection diagrams for surge protection devices (SPDs). Below you will find single-phase and three-phase diagrams for different grounding systems: TN-C, TN-S and TN-C-S. They are clear and understandable for the common man.

Today there are a large number of SPD manufacturers. The devices themselves come in different models, characteristics and designs. Therefore, before installing it, be sure to study the passport and connection diagram. In principle, the essence of connection for all SPDs is the same, but I still recommend reading the instructions first.

All laid out diagrams contain RCDs and group circuit breakers. I indicated them for clarity and completeness of the distribution panel. This “filling” of your shield may be completely different.

1. SPD connection diagram in a single-phase network of the TN-S grounding system.

This diagram shows an SPD of the Easy9 series from Schneider Electric. The following conductors are connected to it: phase, zero working and zero protective. Here it is installed immediately after the introductory machine. All contacts on any SPD are marked. Therefore, where to connect the “phase” and where to connect the “zero” can be easily determined. A green flag on the case indicates a working condition, and a red flag indicates a faulty cassette.

The presented device belongs to class 2. It alone is not capable of protecting against a direct lightning strike. Competent selection of SPDs is a complex and separate topic.

I think everything is clear here...

Below is a similar diagram for connecting an SPD, but without an electric meter and using a common RCD.

2. SPD connection diagram in a three-phase network of the TN-S grounding system.

The diagram also shows an SPD manufactured by Schneider Electric of the Easy9 series, but for a 3-phase network. The figure shows a 4-pole device with a neutral working conductor connected.

There is also a 3-pole SPD of the same series. It is used in the TN-C grounding system. It does not have a contact for connecting the neutral working conductor.

3. SPD connection diagram in a three-phase network of the TN-C grounding system.

The SPD from IEK is shown here. This diagram is a regular input panel for a private house. It consists of an input circuit breaker, an electric meter, an SPD and a general fire protection RCD. The diagram also shows the transition from the TN-C to TN-C-S grounding system, which is required by modern standards.

The first picture shows a 4-pole input circuit breaker, and the second picture shows a 3-pole one.

Above are visual diagrams for connecting an SPD. I think they are clear to you. If you have any questions, I’m waiting for them in the comments.

Let's smile:

There is no more permanent connection than a temporary twist!

If your home has a lot of expensive household appliances, it is better to take care of organizing comprehensive electrical protection. In this article we will talk about surge protection devices, why they are needed, what they are and how they are installed.

The nature of pulse overvoltages and their impact on technology

Many people have been familiar since childhood with the fuss of unplugging household electrical appliances at the first sign of an approaching thunderstorm. Today, the electrical equipment of city networks has become more advanced, which is why many people neglect basic protection devices. At the same time, the problem has not disappeared completely; household appliances, especially in private homes, are still at risk.

The nature of the occurrence of pulse overvoltages (IP) can be natural and man-made. In the first case, IP occurs due to lightning striking overhead power lines, and the distance between the point of impact and consumers at risk can be up to several kilometers. It is also possible to strike radio towers and lightning rods connected to the main grounding circuit, in which case an induced overvoltage appears in the household network.

1 - remote lightning strike on power lines; 2 - consumers; 3 - ground loop; 4 - close lightning strike to power lines; 5 - direct lightning strike to the lightning rod

Man-made power sources are unpredictable; they arise as a result of switching overloads at transformer and distribution substations. With an asymmetrical increase in power (only in one phase), a sharp voltage surge is possible; it is almost impossible to foresee this.

Pulse voltages are very short in time (less than 0.006 s), they appear systematically in the network and most often pass unnoticed by the observer. Household appliances are designed to withstand overvoltages up to 1000 V, these occur most often. At a higher voltage, failure of the power supplies is guaranteed; insulation breakdown in the wiring of the house is also possible, which leads to multiple short circuits and fire.

How the SPD works and how it works

The SPD, depending on the protection class, may have a semiconductor device based on varistors, or have a contact arrester. In normal mode, the SPD operates in bypass mode, the current inside it flows through a conductive shunt. The shunt is connected to protective grounding through a varistor or two electrodes with a strictly regulated gap.

During a voltage surge, even a very short one, the current passes through these elements and spreads along the grounding or is compensated by a sharp drop in resistance in the phase-zero loop (short circuit). After the voltage stabilizes, the arrester loses its capacity, and the device operates in normal mode again.

Thus, the SPD closes the circuit for a while so that the excess voltage can be converted into thermal energy. In this case, significant currents pass through the device - from tens to hundreds of kiloamperes.

What is the difference between protection classes

Depending on the causes of IP, two characteristics of the increased voltage wave are distinguished: 8/20 and 10/350 microseconds. The first digit is the time during which the PI reaches its maximum value, the second is the time it takes for it to fall to nominal values. As you can see, the second type of overvoltage is more dangerous.

Class I devices are designed for protection against power surges with a characteristic of 10/350 μs, which most often occur during a lightning discharge in power lines closer than 1500 m to the consumer. The devices are capable of briefly passing current from 25 to 100 kA through themselves; almost all Class I devices are based on arresters.

Class II SPDs are focused on IP compensation with a characteristic of 8/20 μs, the peak current values in them range from 10 to 40 kA.

Protection class III is designed to compensate for overvoltages with current values less than 10 kA with an IP characteristic of 8/20 μs. Protection class II and III devices are based on semiconductor elements.

It may seem that installing only Class I devices as the most powerful is enough, but this is not the case. The problem is that the higher the lower threshold of the throughput current, the less sensitive the SPD is. In other words: at short and relatively low IP values, a powerful SPD may not work, and a more sensitive one will not cope with currents of such magnitude.

Devices with protection class III are designed to eliminate the lowest voltages - only a few thousand volts. They are completely similar in characteristics to the protection devices installed by manufacturers in power supplies for household appliances. In case of backup installation, they are the first to take on the load and prevent the operation of the SPD in devices whose service life is limited to 20-30 cycles.

Is there a need for an SPD, risk assessment

A complete list of requirements for organizing protection against power supply is set out in IEC 61643-21; mandatory installation can be determined using the IEC 62305-2 standard, according to which a specific assessment of the degree of risk of a lightning strike and the consequences caused by it is established.

In general, when supplying power from overhead power lines, installing a class I surge protector is almost always preferable, unless a set of measures has been taken to reduce the impact of thunderstorms on the power supply mode: re-grounding of supports, PEN conductor and metal load-bearing elements, installation of a lightning rod with a separate grounding loop, installation potential equalization systems.

An easier way to assess risk is to compare the cost of unprotected household appliances and security devices. Even in multi-storey buildings, where overvoltages have very low values with a characteristic of 8/20, the risk of insulation breakdown or failure of devices is quite high.

Installation of devices in the main switchboard

Most surge protectors are modular and can be installed on a 35 mm DIN rail. The only requirement is that the shield for installing the SPD must have a metal casing with a mandatory connection to the protective conductor.

When choosing an SPD, in addition to the main performance characteristics, you should also take into account the rated operating current in bypass mode; it must correspond to the load in your electrical network. Another parameter is the maximum limiting voltage; it should not be lower than the highest value within the daily fluctuations.

SPDs are connected in series to a single-phase or three-phase supply network, respectively, through a two-pole and four-pole circuit breaker. Its installation is necessary in case of soldering of the spark gap electrodes or breakdown of the varistor, which causes a permanent short circuit. The phases and protective conductor are connected to the upper terminals of the SPD, and the neutral conductor is connected to the lower terminals.

SPD connection example: 1 - input; 2 - automatic switch; 3 - SPD; 4 - grounding bus; 5 - ground loop; 6 - electricity meter; 7 - differential automatic; 8 - to consumer machines

When installing several protective devices with different protection classes, their coordination is required using special chokes connected in series with the SPD. Protective devices are built into the circuit in ascending order of class. Without approval, more sensitive SPDs will take the main load and fail earlier.

Installation of chokes can be avoided if the length of the cable line between devices exceeds 10 meters. For this reason, class I SPDs are mounted on the façade even before the meter, protecting the metering unit from overvoltages, and class two and three are installed, respectively, on the ASU and floor/group switchboards.

Proper placement of surge suppressors in the power supply line is fundamental to the correct operation of the designed surge protection system.

As noted earlier, when organizing surge protection systems for power electrical equipment, limiters are mounted in the following places:

outside the construction site, in lightning protection zone 0B, at the entrance of power cables to devices (usually class II limiters, sometimes class I);
at the point where power cables pass through the building wall (depending on the level of threat, these are Class I or II limiters) - in a cable connection, grounded along the shortest path to a grounding device;
inside the construction site:
- in local distribution boards (depending on the level of threat, these are class II or III limiters);
- close to the protected devices (usually these are Class III limiters, sometimes - Class II, from the point of view of the too small rated current of Class III limiters, which is most often 16 A).

It must be emphasized here that of all the locations for surge suppressors suggested in section 443 of IEC 60364-4, the only correct location is in a cable connection, provided that the connection is in the wall of the building being protected.

Placement of limiters in the overhead line:

In the case of placing limiters in an overhead line, we must not forget about the possibility of overvoltage shocks penetrating the power cable along the overhead line pole - building route, which makes this placement useless.

Placement of limiters inside the building:

1.6. Resistance of limiters to short circuit

Surge suppressors must be protected against the effects of short-circuit current. From its connection diagram (parallel connection relative to the terminals of the protected circuit) it follows that any action of the surge suppressor subsequently causes a short circuit current to flow in the protected line. For this reason, the manufacturer must state when and which fuse should be used in series with the surge suppressor to ensure adequate short-circuit current capacity of the fuse-surge suppressor circuit.

When determining the need to use additional protection of a surge suppressor with a fuse connected in series, you should compare the values of the rated currents I F1 of the phase fuses of the protected circuit with the permissible value of the current I DOP that can flow in the circuit of the surge suppressor (recommended by the manufacturer). Depending on the results of such a comparison, the following scheme should be used:

I F1 ≤ I DOP - without additional protective fuse (Fig. 1.3.a),
I F1 > I DOP - containing an additional fuse F2 connected in series with surge suppressors (Fig. 1.3.b).

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1.7. Connection diagrams for surge suppressors

Depending on the grounding system of the power supply network, one of the types of connection of surge suppressors shown in Fig. 1.4, 1.5 or 1.6.

In a TT network system, it is possible to use 4 standard surge suppressors or the so-called 3+1 system (3 surge suppressors + 1 N-PE suppressor). Such connection systems apply to class I and class II limiters.

If class I limiters are used, it is necessary to use systems with additional fuses connected in series with the limiters. The use of fuses is not necessary if the relevant conditions described in section 1.6 are met.