The structural imperfection of electrical networks is the main cause of sudden voltage surges. It is impossible to predict the time of the next drop. The only thing we can do to prevent unpleasant consequences is to protect electrical consumers in our home in advance. In this article we will tell you how and with what to protect the network of your apartment and house.

What will save you from a surge?dressing up

Protection against voltage surges is possible using different types of protective devices. We'll talk about the most common ones. These are voltage control relays (RN) and household stabilizers.

Surge Protection Relay

Protecting your home from power surges using a LV is recommended in cases where the voltage in the network is stable and its noticeable surges are rare. RN is a device capable of reading the parameters of an electric current and breaking the electrical circuit at the moment when the indicators go beyond a given range. After the indicators in the general network are normalized, the device will automatically close the circuit and restore power to consumers. The function of restoring power after a specified period of time (with a delay), built into the 220V voltage relay for the home, helps extend the life of some household devices, refrigerators, etc.

LVs have small dimensions, relatively low cost and good performance. The disadvantages of RNs include their inability to smooth out fluctuations in electrical energy. For maximum protection of all consumers, you will need to install several devices at once.

The LV protects the network only from unacceptable voltage surges and is not intended to protect against short circuits (this function is performed by circuit breakers).

Modern launch vehicles come in three types:

1. A stationary relay built into the electrical panel of a house or apartment.

2. Relay for individual protection of one consumer.

3. Individual protection relay for several consumers.

If everything is almost clear with the operation of relays of the second and third types, then the first type LV has a more complex design, and its installation requires certain knowledge. Such devices are mounted at the entrance to the premises, thus providing protection against power surges in the network of all household electrical equipment.

Selecting a launch vehicle

When choosing a relay to protect your home network, it is enough to know the rating of the electric current that the input circuit breaker is capable of passing through. If, for example, the switch capacity is 25A (which corresponds to a power consumption of 5.5 kW), then the performance characteristics of the LV should be one step higher - 32A (7 kW). If the switch is designed for 32A, then the relay must withstand a current of 40 - 50A.

loa FORUMHOUSE user

For this case, I took a 40 A relay, with an input circuit breaker of 25/32 (the first one is, but the setting will increase).

Some people choose a PH brand based on total power consumption. This is not entirely correct. After all, a relay capable of withstanding a current of 32A can safely operate both at a load of 7 kW and at a much higher power consumption. Only in the second case, it is necessary to integrate a special magnetic contactor into the working circuit of the LV. But more on that in the next section.

LV installation

The standard diagram for installing a LV in a distribution panel is shown in the figure. This is the simplest protection against power surges.

Work on installing the pH should only be carried out with the main switch turned off!

As you can see, everything is simple: the control relay is installed immediately after the electric meter and is connected to the phase wire through which power is supplied to the entire house. When a surge occurs beyond the set (adjustable) range, the relay disconnects the external power supply from the internal electrical wiring, and protection against voltage surges is provided in the apartment and in the house.

The pH mounted in the panel panel takes up minimal space on the DIN rail.

If the power of home network consumers totals 7 kW or more, manufacturers strongly recommend integrating an additional electromagnetic contactor into the operating circuit of the LV. Although, a reliable contactor in the overall scheme will never become an extra detail, see the following comment:

Vitichek FORUMHOUSE user

It is better to install a contactor to any relay, although manufacturers write that the LV can withstand high currents. The contactor has larger contacts and lower resistance.

This device helps relieve the load on the LV contacts, independently disconnecting the power line from the general network of household consumers. The control relay, at the moment of unacceptable overvoltage, only issues a shutdown command. After this, the electromagnetic coil of the contactor disconnects the power contacts connecting the external and internal networks. The connection diagram in this case will be as follows:

Overvoltage protection system.

Protection against voltage surges 220V

In order for the LV to benefit its owner, its operating parameters (permissible voltage limits and power resumption delay time) must be correctly adjusted. If the operating circuit uses one pH, then the limits of permissible values ​​should be set based on the characteristics of household appliances that are sensitive to changes. The most sensitive and expensive equipment is audio and video equipment. The range of permissible voltage values ​​for it is 200 – 230V.

The permissible voltage deviation from the nominal values ​​in domestic energy networks is 10% (198...242V). In the case of frequent activation of the LV, these indicators can be taken as a basis when adjusting the relay. However, in this case it is recommended to protect sensitive consumer electronics with the help of low-priced portable stabilizers.

DenBak FORUMHOUSE user

Nobody says that you need to turn off at plus or minus 15V. There is a range of maximum permissible deviations of 10%, which most devices should withstand. Based on this, you need to set approximately 190V-250V. Although, with our state of networks, especially in the private sector, everything is expected. So reasonable caution won't hurt.

In order to ensure the most reliable protection for all consumers, an electrical circuit with several relays should be used. A working protection scheme, including several LVs, allows consumers to be divided into groups - in accordance with their sensitivity to overvoltage:

1. The first group includes audio and video equipment (permissible voltage values ​​- 200 - 230V);
2. The second includes household appliances equipped with an electric motor: refrigerators, air conditioners, washing machines, etc. (permissible values ​​- 190 - 235V);
3. The third group is simple heating devices and lighting (permissible values ​​- 170 - 250V).

Each consumer group is connected to its own RN. In this scheme, the operating parameters of each relay are configured individually.

Protecting the network from overvoltage and surges.

The power resumption delay time must comply with the operating requirements for household appliances. For some refrigerators, for example, the recommended delay is 10 minutes.

Three-phase network protection using LV

If the power supply to your home is carried out through a three-phase system, then it is advisable to install a separate control relay for each phase.

Three-phase voltage relays are designed solely to protect the relevant equipment (electric motor, etc.). If such a relay is installed at the entrance to the home, then a voltage imbalance in one of the phases leads to de-energization of all single-phase consumers.

Surge Protectors

If your house experiences constant power surges, the LV will operate several times a day, de-energizing the entire house. Therefore, in such cases, a less simple, more expensive, but also more practical method of protecting home electronics is recommended. It consists of using stabilizers - devices that smooth out voltage surges in the external network, producing a constant 220V output.

Based on the type of connection, there are two types of stabilizers: local (which are connected to an outlet, protecting from one to several consumers) and stationary (connected to the input power cable and protecting all consumers of the home network). Local stabilizers should be used to protect the most sensitive household appliances. They can be used in conjunction with a stationary launch vehicle.
Stationary stabilizers are complex devices that not only smooth out voltage drops throughout the entire household network, but are also capable of saving expensive equipment by automatically turning off the power to consumers when overloaded and reaching critical values.

It is highly recommended to install stationary stabilizers if the voltage value goes beyond 205...235V several times a day (this can be determined using an ordinary tester).

If the lights in the house are constantly blinking, and the voltage goes beyond 195...245V, then using household electrical appliances without a stabilizer is prohibited!

How to choose a stabilizer

The stabilizer should be selected based on the total power of household consumers. The device must have a decent amount of power.

How to Simply choose a high-quality LV for an apartment or a private house, which is better, a LV or a stabilizer, a diagram for connecting the LV to a 220V network, installing the LV in a panel.

It is believed that all modern household appliances are automatically protected. Expensive plasma panels are already built-in control relay or stabilizer, but more often than not, a high potential difference “breaks through” the built-in stabilizers and the equipment burns out.

TEST:

4 questions about how you can protect your equipment from shocks

• How often do you experience changes?

a) every few days;

b) very rarely.

• Do the light bulbs in the apartment flicker (change brightness)?

a) yes, constantly;

• What is the average load power of all your appliances?

a) less than 4 kW;

b) more than 4 kW.

• Do you often get traffic jams?

a) no. Knocks out when we turn on several powerful devices;

b) yes, sometimes you even have to change the plugs.

Test results:

b, b, b, b - a relay will suit you. RN will protect your equipment from sudden surges. Also, you need to install a more powerful plug. Your plugs are designed to carry less total current than your electrical appliances assume;

a, a, a, a - a stabilizer will suit you. Your power consumption is not high, an inexpensive device will “calm down” the voltage in the network;

a, a, a, b - ideally, an LV and a stabilizer will suit you, this will protect the apartment/house from sudden surges and equalize the voltage to a constant norm.

5 main reasons for voltage drops in the 220V network

Mains voltage is rms, i.e. actual value of the potential difference in an AC electrical network current, accessible to consumers. Basic parameters of the AC network - potential difference And frequency, in Russia the standard is: frequency 50 Hz and 230 V.

Due to imperfections, the power supply system is not always able to provide 220 Volt stability. With a sharp, short-term surge, electrical appliances are ready to fail, despite the built-in fuses and voltage relays built into the device circuit.

The potential difference in the network can change noticeably not only because of problems outside the apartment or house. Deviations from 220 Volts occur due to increased load on the network from switched on devices.

The cause of the fluctuations is outdated elements of power supply systems. Modern energy consumption systems have an excessive load wiring, it was not designed for such power at the time it was designed.

The reasons for the differences are as follows:

• Several electrical appliances are turned on (and then turned off) at the same time;
• The neutral conductor is broken;
• Lightning strike during a thunderstorm;
• Damage to wires on power lines;
• Incorrect wiring in the electrical panel.

Horse racing is out of our control, so you will need to protect your home network from this issue in advance.

The most reasonable solution to the problems of fluctuations is to completely reconstruct the power supply system. If you live in a private house, then completely replacing the wiring is realistic and quite affordable, but, in reality, this will only reduce the likelihood of surges; new wiring does not guarantee the absence of interruptions Power lines.

2 ways to protect against surges

Today, there are the following 3 types of devices that can save your equipment from sudden surges:

• RKN (Voltage control relay);
• Voltage regulator;

1 main reason that UPSs are not able to cope with surges.

Uninterruptible power supply and stabilizer- Different things. Many people confuse these two types of devices, which is due to an illiterate description. UPS in stores and ignorant sales assistants.

Let's figure out why we need an uninterruptible power supply. UPS used with a computer. Its main task is to prevent sudden shutdowns and keep the batteries charged for some time.

What happens if there is a strong drop? If UPS contains a stabilizer (which is extremely rare), it will preserve the integrity of the computer; if it does not, it will fail. All other household appliances not connected to the UPS will be under attack.

2 types of relays to protect household appliances and equipment. Uzip or relay.

Voltage control relay(RKN) is a simple device that turns off the circuit when the potential difference deviates from the norm. A relay for protecting household appliances and equipment switches the circuit back on when the potential difference becomes normal.

RKN does not change the voltage, does not stabilize it, the relay reads the indicators and acts according to the network.

Why do you need a voltage relay (RN) for a 220V home network?

Relay there are two types:

1. Relay general type. It is installed in the shield, RN protects the entire house (or apartment) from surges. RKN It is sensitive, does not respond to surges within a microvolt, and turns off the current supply when the potential reaches a critical value. The critical value depends on the specific model RKN. Adjustment of such devices is very easy: for example, relays RN-113 can be set up in 10 minutes without any special knowledge; Setting up the Barrier takes even less.
2. RKN built-in It plugs into a power outlet and resembles an extension cord with 220 Volt sockets. It includes individual electrical appliances and RN can protect them from overvoltage. The design of the relay is very simple - a plate that bends when the voltage increases presses the automatic toggle switch. This is why there is a noticeable “click” when triggered.

1 tip on how to choose the right pH for an apartment or private house

If you decide to purchase a control relay, remember that you should carefully study its power (more than the sum of the powers of all electrical devices included).

A relay is a convenient device, but is not entirely suitable in areas where the network is unstable. In this case, the relay will turn on and off very often; few people will like the constantly flickering light. The relay will preserve your household appliances, but at the cost of comfort.

Protection against voltage surges in the 220V network

3 main differences between relays and each other.

All single phase relays (i.e. relay, operating in a single-phase network, a standard two-contact network with a desired 220 V) differ from each other in the following parameters:

• maximum switched load current (total current). These are relays with ratings of 16A, 25A, 32A, 40A, 60A, 63A. Relays with high load currents are installed in production.
• presence of a network voltage indicator;
• controls (knobs that allow you to adjust the acceptable range);

How to Avoid Connection Problems, 3 Relay Connection Mistakes

Consider the three most common mistakes that happen when connecting incorrectly voltage relay:

1. Connection of the zero with the protective conductor coming after the differential circuit breaker. This is most often done “out of habit”, in order to achieve zeroing.
2. Single-phase connections of the device. Also a common mistake: a phase is connected to a differential machine, but the zero passes by. Thus, the zero of a household outlet is connected not to a differential circuit breaker, but to a zero busbar.
3. Error in incorrect polarity. When one pole is connected, the terminals are swapped, so the supply phase is connected to the upper terminal, and the outgoing phase to the lower, the supply zero from the zero bus is connected to the lower terminal, and the load to the upper.

4 types of voltage stabilizers

Unlike a relay, which de-energizes the network until the voltage returns to normal, the stabilizer works in the other direction - it normalizes the network. They are connected to the electrical network and, regardless of the voltage in the incoming network, the output parameters are 220 Volts. If changes occur frequently, this device will be an excellent solution, because, unlike a relay, it does not turn off the current. With a stabilizer, you guarantee not only the safety of your household appliances, but also their continuous operation.

• Relay. Cheap devices with low power.
• Servo driven. It is also called electromechanical. Its power is higher than that of relay ones, and the price is also higher.
• Electronic. Their design includes semiconductor parts - thyristors and triacs. They are very durable, powerful and accurate. They are not cheap, but they are guaranteed to protect your equipment from surges and ensure a stable network.
• Electronic double conversion. The most expensive and most reliable stabilizers. Their operating principle involves stabilization and complete equalization of the potential difference. These stabilizers level the incoming network twice. They are perfect for homes with a very unstable network, where the voltage in the outlet literally “jumps.”

TOP 2: THE MOST POPULAR RELAY AND STABILIZER

Let's conduct a full review of the main characteristics of the RN-113 relay:

4 diagrams for connecting RN-113 to a 220V network

RN-113 installed in the network after a circuit breaker or plug.

The lower limit is the minimum voltage at which RN turns on (if the potential difference is above the lower one) and turns off (if it is below the lower one)

The upper limit is the maximum voltage above which RN turns off the network.

The lower and upper limits of the barrier are set using the control knobs.

4 detailed circuits for monitoring voltage in a 220V network on a DIN rail

If the voltage rises above the upper pH, it will operate within 0.02 seconds - much faster than if the potential difference falls below the lower one - 0.12 seconds. This is logical - after all, a decrease is not as dangerous as an increase.

Diagram of detailed connection of the LV to a 220V network

2 diagrams for installing the LV in the shield

detailed connection diagram with contactor

detailed diagram of the LV connection - installation in the panel

Connection rules are regulated by SNiP 3.05.06-85 " Electrical devices" and SNiP RD 34.20.179 " Standard instructions for compensating capacitive ground fault current in electrical networks».

Let's conduct a full review of the main characteristics of the SVEN AVR-2000 LCD stabilizer:

As you can see, this popular stabilizer- a device that normalizes the output potential difference and automatically RN. At a voltage above 280 Volts (according to GOST, the maximum permissible 240 V), the stabilizer will turn off the network within 0.01 seconds. When the load current is higher than 15 Amperes (power about 3.5 kilowatts), the fuse will trip and the device will turn off. If the network is less than 100 Volts, the device will not work at all. The device helps to configure the barrier thanks to 2 control knobs.

Stabilizer connection diagram

The test results for this stabilizer model can be summarized in the following graph:

This graph clearly shows that in the range from 170 Volts to 280 Volts, the stabilizer maintains 100% power. If the voltage is critically low (100 Volts), the stabilizer outputs 50% of the power (which is absolutely harmless for all electrical appliances).

STILL IMPORTANT TO KNOW: 3 advantages and disadvantages of voltage relays and stabilizers

Advantages	Flaws
RN
Small dimensions, DIN rail mounting	Does not equalize potential differences
Low cost	Multiple devices required for full protection
Reacts more quickly in case of a sharp jump
Stabilizer
Guarantees stable 220 Volts, ideal for all electrical appliances. In case of excessive decrease or increase, the stabilizer turns off the network.	They are large in size and get very hot during operation, so the stabilizer will need a separate place. Very sensitive to increased humidity. The transformer located inside actively attracts dust.
Equipment connected to the stabilizer remains operational. Even audio and video equipment that is sensitive to changes continues to work stably.	High price.
All light bulbs stop flickering, which significantly extends their service life.	Sensitive to interference. If interference in the network is a normal and constant phenomenon, the stabilizer will begin to fail over time and turn off the network more and more often.

2 main arguments for and against. Which is better - RN or stabilizer.

From our comparative characteristics it is clear that the dignity RN- lack of stabilizer. If your home rarely experiences fluctuations, the network is relatively stable, but there are sudden and very high spikes, then more suitable for you RN, its response speed is much higher and it will turn off the apartment in time.

If you have an unstable network, the potential difference is constantly low, after which it rises to normal in several jumps and fluctuates around 200-220 Volts, you need a stabilizer, it will level the network, and all devices will work more stable.

Here are examples from real life:

Alexander, 32 years old, Omsk

“A week ago there was a surge in the house. There was smoke coming out of the TV in the back and from the socket. The TV went off immediately. Things were even “more fun” for the neighbor: the refrigerator, plasma, two light bulbs and washing machine burned down. One can only guess what the voltage was, judging by the burnt-out light bulbs, it was 300 volts. Something burned out in every apartment. We consulted an electrician. It was decided to install the launch vehicle, it should have been done earlier"

Svetlana, 54 years old, Moscow region

“We’ve been living at the dacha for two years now. The light blinks constantly, it’s impossible to get used to it, it’s terribly annoying. We went to the administration, to the district service - no one cared. Country house? Be glad that there is light. My husband installed the LV, but it doesn’t do much good; he turns off the lights about 10 times a day. The stabilizer solved the problem, now the light does not blink"

We conclude: a stabilizer together with a LV - 2 in 1 is capable of completely protecting an apartment or house. The relay will ensure quick shutdown in the event of an extremely sharp jump, and the stabilizer will level the potential difference to normal 220 Volts.

ANSWERS TO 5 FREQUENTLY ASKED QUESTIONS

The lights in the apartment are constantly blinking, what should I do?

Constant flickering of the lights indicates network “jumps”. This is extremely harmful for electrical appliances containing semiconductors, such as televisions, computers, and audio-video equipment. This can be corrected by installing a stabilizer.

RN installed. Now the lights turn off several times a day. What to do?

Every time the relay de-energizes the apartment, this means that the voltage has gone beyond the permissible range: it has either dropped too much or risen. If this happens to you all the time, then you have a very unstable network. You need a stabilizer.

How to calculate the power of the stabilizer that will suit me?

Take all the household appliances you have and calculate their total power. Remember, the refrigerator is always working, the light bulbs in the rooms and the TV: everything needs to be taken into account.

When connecting a relay and a stabilizer together, what should be connected to what?

On the incoming line you must first install the RN, then the stabilizer. The LV passes any voltage that falls within the permissible range, and the stabilizer will bring it back to normal.

Is the stabilizer mounted on a DIN rail?

No, these are large devices. They are not DIN rail mounted. They are sensitive to moisture and dust, they are installed only where it will be dry and clean.

The magnitude of the voltage deviation in a household network is regulated by GOST 32144-2013. It states that the increase or decrease in voltage should not exceed 10% of the rated value. Failure to comply with GOST requirements leads to failure of household appliances. Household electrical appliances are designed to operate in the range of supply voltages that are mentioned in GOST. Exceeding the voltage threshold of 242V causes electrical appliances to operate in a critical mode, overheating, failure of electronic components, and insulation breakdowns occur. The consequence of this is equipment failure and even fire.

Fire is a consequence of increased voltage

Signs of increased network voltage

1. Often fail lamps.
2. Incandescent and halogen lamps shine brighter than usual.
3. Light intensity changes periodically.
4. Unusual behavior household appliances at work.
5. Unexpected reboot the computer or turning it off.
6. Malfunctions consumer electronics.

If the voltage goes beyond the permissible limits, household electrical appliances must be turned off immediately. If the situation regularly repeats, contact the sales company.

Reasons for increasing network voltage

1. Phase imbalance. AC networks are three-phase. The voltage between each phase and zero is 220 V. When designing the electrical wiring of a house or holiday village, consumers (apartments or private houses) are distributed equally among the phases. But this does not mean that the load will be divided equally between phases. The difference in consumption leads to a redistribution of voltage values ​​across phases: where less is consumed, there is more voltage. Most often this factor manifests itself in rural areas.
2. Zero interruption of the power supply network. This is an emergency mode of network operation that must be eliminated immediately. As a result of an accident with a zero break, the voltages are redistributed even more than in the case of phase imbalance. If in the first case, in the absence or with minimal load of one phase, the voltage on it is increased, then in the second case it will approach 380 V! As a result, in a few seconds, all household appliances that were not lucky enough to be working at the time of the accident will die. Then litigation begins with the network organization for damages, because its task is to audit contacts and monitor their condition. A re-grounding loop helps smooth out the consequences of a zero break in the network, but the further the substation is from the consumer with the loop, the less effective it is. Within the city limits, it is impossible to create a personal grounding loop.
3. Lightning strikes close to consumers cause a short-term increase in voltage in their electrical wiring. In modern networks, the design necessarily provides for surge protection, but old networks do not have it and are therefore vulnerable.
4. Errors during installation or repair. Inexperienced or inattentive electricians may, when working in the panel, either connect two phases (380V) to the consumer, or forget to connect the neutral wire in place (case of a broken neutral). Therefore, if you have any doubts about the electrician’s qualifications, do not trust him with the job.

Methods of protection against overvoltage

• 1. Installation of voltage control relay. When the voltage in the network increases, it will turn off electrical appliances and save them. When the voltage returns to normal, the relay will turn them back on. Among the voltage control relays, there are two groups: for connection to a socket and for installation in a distribution panel. In the first case, one consumer is protected, in the second – all electrical equipment in the house.

• 2. helps protect the equipment connected to it: computer, TV, router – from minor overvoltages in the network. It smooths out only impulse effects and does not change the voltage value. Remember: not everything that is called a “surge protector” actually is one; sometimes ordinary extension cords with a block of sockets are sold under this name. They do not contain any filling that acts as protection against interference, surges and overloads. Buy only surge protectors from reputable companies.

• 3. Stabilizer protects equipment without disconnecting it from the network. When the input voltage changes in the operating range, it outputs 220 V. But when the input voltage exceeds the threshold value, it turns off. This additionally provides protection against zero loss. The stabilizer does not protect against surge voltages.

• 4. Uninterruptible Power Supply (UPS) performs all the functions of a stabilizer and surge protector, but when the voltage is turned off or its value increases above the permissible value, it switches to powering the load from the battery.

• 5. SPD— surge protection device. Protects electrical equipment from overvoltages caused by nearby lightning strikes.

Surge protection device

Modern home appliances contain sensitive electronics, making these devices vulnerable to power surges. Since it is not possible to eliminate them, reliable protection is necessary. Unfortunately, its organization is not the responsibility of the housing and communal services service, so you have to deal with this issue yourself. Fortunately, purchasing protective devices is not a problem today. Before moving on to the description and principle of operation of such devices, we will briefly talk about the reasons that cause voltage surges and their consequences.

What is voltage drop and its nature?

This term refers to a short-term change in the amplitude of the power supply voltage, followed by restoration close to the original level. As a rule, the duration of such a pulse is calculated in milliseconds. There are several reasons for its occurrence:

1. Atmospheric phenomena in the form of lightning discharges can cause an overvoltage of several kilovolts, which is not only guaranteed to damage electrical appliances, but can also cause a fire. In this case, it is easier for residents of high-rise buildings, since organizing protection from such predictable phenomena is the responsibility of electricity suppliers. As for private houses (especially with air inlet), their residents should deal with this issue on their own or contact specialists.
2. Jumps during switching processes when powerful consumers are connected and disconnected.
3. Electrostatic induction.
4. Connecting certain equipment (welding, commutator motor, etc.).

The figure below clearly demonstrates the magnitude of the lightning impulse (U gr) and switching impulse (U k) in relation to the rated network voltage (U n).

To complete the picture, mention should be made of long-term increases and decreases in voltage. The cause of the first is an accident on the line, as a result of which the neutral wire breaks, which causes an increase to 380 volts. No devices will be able to normalize the situation; you will have to wait until the accident is resolved.

Long-term voltage drops can often be observed in rural areas or holiday villages. This is due to insufficient power of the transformer at the substation.

What is the danger of fluctuations?

In accordance with acceptable standards, deviations from the nominal value are allowed in the range from -10% to +10%. During surges, the voltage can significantly go beyond the established limits. As a result, power supplies of household appliances are overloaded and may fail or significantly reduce their service life. With high or long-term differences, there is a high probability of ignition of the wiring, and, as a result, a fire.

Low voltage also threatens trouble, especially for refrigeration compressors, as well as many switching power supplies.

Protective devices

There are several types of protective devices that differ in both functionality and cost, some of them provide protection to only one household appliance, others – to all those in the house. We list the well-proven and most common protective devices.

Network filter

The simplest and most affordable option for protecting low-power household equipment. It has proven itself to be excellent at surges up to 400-450 volts. The device is not designed for higher impulses (at best, it will take the blow on itself, saving expensive equipment).

The main protection element of such a device is a varistor (a semiconductor element that changes resistance depending on the applied voltage). It is this that fails when a pulse exceeds 450 V. The second important function of the filter is protection against high-frequency interference (occurring during operation of an electric motor, welding, etc.) that negatively affects electronics. The third element of protection is a fuse that trips during a short circuit.

Filters should not be confused with ordinary extension cords, which do not have protective functions, but are similar in appearance. To distinguish them, just look at the product passport, which contains full characteristics. The absence of such should in itself raise suspicion.

Stabilizer

Unlike the previous type, devices of this class allow you to normalize the voltage in accordance with the nominal one. For example, by setting the limit within 110-250 V, the output of the device will be a stable 220 V. If the voltage goes beyond the permissible limits, the device will turn off the power and resume its supply after the operation of the electrical network is normalized.

In some cases (for example, in rural areas), installing a stabilizer is the only way to increase the voltage to the required level. Household stabilizers come in two modifications:

• Linear. They are designed to connect one or more household appliances.
• Trunk, installed at the entrance to the electrical network of a building or apartment.

Both the first and second should be selected based on the load power.

Uninterruptible power supplies

The main difference from the previous type is the ability to continue supplying power to the connected device after the protection has tripped or a complete power outage. The operating time in this mode directly depends on the battery capacity and load power.

In everyday life, these devices are mainly used to connect desktop computers, so as not to lose data in case of problems with the electrical network. When the protection is triggered, the UPS will continue to supply power for a certain time, usually no more than half an hour (depending on the characteristics of the device). This time is enough to save the necessary data and shut down the computer correctly.

Modern UPS models can independently control the operation of the computer via a USB interface, for example, close a text editor (after saving open documents), and then turn off. This is a rather useful function if the user was not nearby when the protection was triggered.

Surge protection devices

All of the devices listed above have a common drawback: they do not have effective protection against high voltage pulses. If this happens, it is almost guaranteed to disable such devices. Therefore, the protection must be organized in such a way that after activation it can be promptly brought into working condition. SPDs meet this requirement perfectly. On their basis, a multi-level system for protecting the internal lines of a private home is organized.

One of the accepted classifications of such devices is shown in the table.

Table 1. SPD classification

Category	Application
B (I)	Provide protection in the event of a direct hit from a lightning discharge through the lightning protection system. Installation location - input distribution device or main distribution board. The main normalizing characteristic is the magnitude of the pulse current.
C (II)	They protect the current distribution network from switching impulses, and also play the role of a second protective level during a lightning discharge. Installation location: distribution board.
D(III)	They provide the last level of protection, in which residual voltage surges and differential overvoltages are not allowed to consumers. In addition, high-frequency interference is filtered. Installation is carried out in front of the consumer. They can be made in the form of a module for a socket, an extension cord, etc.

An example of three-level protection is shown below.

SPD design features.

The device is a platform (C in Fig. 6) with a replaceable module (B), inside of which there are varistors. If they fail, the indicator (A) will change color (in the model shown in the figure to red).

SPD Finder (category II)

Externally, the device resembles a circuit breaker, the mounting is the same (for DIN rail).

A special feature of SPDs is the need to replace modules when varistors fail (which is quite simple). The modules are designed in such a way that it is impossible to install them on a platform with a different rating. The only serious drawback is related to the characteristic features of varistors. They need time to cool down; repeated exposure to lightning strikes significantly complicates this process.

Safety relay

In conclusion, we will consider voltage control relays (VCRs); these devices are capable of protecting household appliances from switching pulses, phase imbalance, and low voltage. They cannot cope with lightning impulses because they are not designed for this. Their scope of application is protecting the internal network of an apartment, that is, where providing lightning protection is the responsibility of electric companies.

The devices can be installed in the input panel, directly after the electric meter, for this purpose a DIN rail mount is provided.

In addition, modifications of devices are produced in the form of power extension cords and modules for sockets.

These devices can only perform a protective shutdown of the network; if the voltage goes beyond the specified limits (set by control buttons), after normalization of the electrical network it is connected. Stabilization and filtration are not performed.

Cautions

You should not trust the protection of your home to home-made structures; in domestic conditions it can be problematic to configure the assembled circuit and test its operation in critical modes.

Without practical experience in organizing lightning protection, you should not try to implement it yourself; it is better to entrust this work to professionals. We recommend that you consider this part of the article as informational.

All manipulations with the electrical panel, devices and wiring must be carried out only when the power supply is turned off.

Familiar to many users, power surges in the 220V power supply network are very common; they are caused by disruptions in the operation of the transformer substation or overloads in existing power lines. The only way out of this situation is to install a surge protection device in the apartment, ensuring the safe operation of all equipment connected to it (see photo below in the text).

Reliable protection against power surges for all household appliances in the apartment is possible only if the stabilizing devices have sufficient power. Let's try to understand in more detail the types and models of branded units, most often used in domestic conditions and in offices. But first, it is advisable to become familiar with the main types of supply voltage deviations from the norm.

Types of voltage drops

There are several types of voltage drops in the network, classified by their duration and amplitude. In accordance with these characteristics, they are all divided into the following groups:

• Short-term bursts of small magnitude associated with transient processes due to the inclusion of power equipment (elevator or pumping stations connected to the same phase) or with strong lightning discharges;
• Long-term voltage drops below the permissible PUE level;
• Severe excess of the permissible maximum (overvoltage reaching 260-300 Volts) for a long time;
• Constant voltage surges of significant amplitude, arising due to a malfunction of station equipment.

Note! All of the above deviations are arranged in increasing order of their danger for equipment connected to a household network.

Due to this classification, various types of equipment (including devices that respond to short-term surges) must be used to protect against voltage surges. This circumstance presupposes a completely different approach to the selection of protective devices used to connect household appliances.

If, during short-term surges in the network, input two-pole circuit breakers are most often triggered, then in a situation with a long-term voltage exceeding values ​​of the order of 300 Volts, very unpleasant things can happen. In this case, complete burnout of expensive equipment that is not protected by a high-quality stabilizing device is possible. The same consequences are observed if a strong lightning discharge hits a building (this phenomenon is especially dangerous in rural areas).

Methods and means of protection

There are several approaches to preventing emergencies that arise due to disruptions in the normal power supply for the home. Such techniques include:

• Use of special relays in power circuits that provide control of operating voltage (RKN);
• The use of multifunctional surge protection devices (SPM), mounted in the input circuit of the electrical network immediately after the input circuit breaker;
• Setting the release for minimum and maximum voltage (RMM);
• Power supply of household appliances through standard voltage stabilizers;
• Using a powerful “uninterruptible power supply” (UPS) in the apartment.

Let's look at each of the types of protective equipment listed above in more detail.

RKN and UZM

One of the simplest solutions for protecting the electrical network from current surges and overvoltages is to install an RKN type relay with an indicator board or a UZM safety device into it. The essence of the operation of equipment of this class is quite simple and consists of the following:

• The electronic module built into the device continuously monitors the voltage entering the circuit and completely turns it off if the value deviates from the nominal value (in either direction);
• The system operates even after a complete power loss, and when it reappears, it begins to function again, automatically adjusting the nominal value in a given range of values;
• The limits for adjusting the supply voltage parameters are usually set manually.

In addition, voltage relays allow you to set a time delay for turning on the power supply after a power failure in a fairly wide range of values ​​(from 10 seconds to 6 minutes).

Additional Information. For most household devices that are periodically turned on and off (refrigerators and air conditioners, in particular), restarting is carried out with a delay of up to 5 minutes.

Devices of this type are usually mounted in an electrical panel on a special DIN rail with a standard size of 35 millimeters. The advantages of protective devices RKN and UZM include:

• Wide range of setting operating voltage values;
• Possibility of shutdown in case of overcurrent and short circuit;
• High relay response speed (no more than 0.2 sec.).

To this should be added a significant range of output current adjustment (from 25 to 63 Amperes). A sample of these devices is shown in the figure below.

Voltage control relay RMM

The so-called “releases” of supply lines are very similar in principle to the devices already discussed earlier. They also continuously monitor the mains voltage and, in case of extreme deviations in the form of a current surge, instantly turn off the circuit breaker to which the device itself is connected. The device is put back into operation by pressing the “Return” button.

Note! Sometimes this device is manufactured in a common housing with a circuit breaker, that is, it is one whole (a sample device according to the IEK standard is shown in the photo below).

The advantages of RMM type devices include compactness, simplicity of design and quite affordable price. Their only drawback is the absence of an automatic return to the working position.

Voltage stabilizers and uninterruptible power supplies

Stabilizing devices (or simply stabilizers) belong to the category of expensive equipment that provides a high degree of protection of the home network from fluctuations in voltage and current in the load. They are able to guarantee a constant output voltage within specified limits regardless of any changes at the input terminals.

Before purchasing such a unit, first of all, you should decide on the number of consumers simultaneously connected to it, which significantly affects the choice of the brand and power of the stabilizing device. The main advantages of these devices include:

• High performance and durability;
• Increased accuracy of regulation of network parameters;
• Guaranteed constant operating output voltage.

The disadvantages include the high cost of the purchased product and high energy consumption.

When considering UPS-type converters, you must be able to distinguish them from stabilizers based on the presence of built-in batteries. Thanks to this, such devices not only ensure that the voltage is maintained within specified limits, but also guarantee the continuous operation of household consumers connected to them.

Important! The time the voltage is present at the output when it is lost in the network depends on the capacity and quality of charging of the batteries, as well as on the number of loads connected to the UPS.

The cost of these products is also quite high; its specific value depends on the parameters of the device itself and the capacity of the built-in battery. Devices with an uninterruptible power supply function are usually used for very specific devices (a computer, for example, or a TV), where a power loss can lead to loss of information or malfunction of the equipment.

Review of popular models

"ZUBR"

Let's start with such a widespread Ukrainian product as the protective relay of the ZUBR brand, which is in great demand in Russia. This device is guaranteed by the manufacturer for a period of up to 5 years; at the same time, many users speak well of its work.

A relay device with index 25D, for example, is designed for maximum currents of up to 25 Amperes and provides good mains voltage stabilization characteristics (including thermal protection). This model attracts users with a relatively low cost (for Russia it is about 1500-1900 rubles).

"RESANTA"

This product is also quite cheap (up to 700 rubles) and enjoys some popularity among the broad consumer masses. Another advantage is the absence of any manual controls, which in some situations looks like a disadvantage (it all depends on the user’s preferences).

The shortcomings of this system include a wide range of adjustable voltages (from 170 to 265 Volts), which means continued operation of the equipment in conditions that are dangerous for some types of equipment.

Note! Due to the lack of regulatory authorities, it is not possible to change these boundaries.

Let's add to all that has been said the large dimensions of the device and the low speed of protective shutdown (up to 6 seconds). During such a period of time, with strong overvoltages, most devices will definitely burn out. The recovery time of this device is only 2-3 minutes, which is not enough for some types of household equipment (for refrigerators, for example, this figure should be at least 5 minutes).

RN-111A (113)

This model of relay equipment is produced by a well-known and reliable manufacturer (Novatek).

Products of the RN-113 brand have a number of advantages, the main ones of which are given below:

• First of all, this is a fairly high speed of 0.2 seconds (compare with the previous model with its 6 seconds);
• Further, a large range of adjustment of the voltage limits;
• Possibility of independently setting the moment of restart;
• The presence of a digital indicator with operating modes and functional parameters displayed on it.

The only drawback of this device is considered to be the low load capacity (only 16-32 Amperes), which is sometimes not enough for suburban consumption facilities.

In this regard, experts advise supplementing the device with a separate contactor and a special circuit breaker that provides protection for its relay part. As a result, the entire combined design can cost the user about 2.5-3.0 thousand rubles (for the PH 113 model, designed for 32 Amperes, the cost of the kit will increase significantly).

UZM-51M

This device is produced by the St. Petersburg company Meander and is considered one of the most reliable and efficient pieces of equipment in this class.

Its advantages include:

• Quite a wide range of setting voltage limits (from 160 to 280 Volts);
• High performance (response time is only 0.02 seconds);
• Maximum load capacity – up to 63 Amps;
• Availability of a protective mechanism against surge voltages;
• Relatively small in size and no need to supplement the kit with any elements.

Let's add to this the low cost of the product, which can be purchased on the market for about 2 thousand rubles.

In the final part, we note that before making a final decision on the choice of protective equipment, it is advisable to contact a specialist who can assess possible threats and offer the user one or another sample. At the same time, it is important to understand that purchasing, albeit expensive, but quite effective means of protection against power surges and overvoltages is tantamount to a reliable investment of money.

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