Why do you need an automatic voltage stabilizer? Why do you need a voltage stabilizer at home? Fine. What about the current stabilizer?

Low and/or unstable voltage in the power supply network can irreversibly damage all household appliances in your home! And, at the same time, you will most likely be denied free warranty service, since the warranty is valid only if the device is operated under power supply conditions that meet strict technical requirements for supply voltage - 220 volts ±10%.

Especially to solve the problem of unstable power supply to electrical equipment, smoothing out differences and surges in supply voltage deviations in the power supply network (supply voltage stabilization), a special protective device- alternating mains voltage stabilizer (also known as a voltage normalizer, AVR, Automatic Voltage Regulator - automatic voltage regulator, voltage stabilizer or in common parlance - step-up transformer, equalizer, converter, voltage / current rectifier)

Household appliances connected through a voltage stabilizer operate in gentle power supply mode with a stabilized input voltage of the supply network, which allows you to significantly extend its service life and even save on electricity because All household appliances are initially designed for a specific network voltage value, and it is at this voltage that the optimal operating mode and the highest efficiency are ensured.

Voltage stabilizers can also be used to protect electric motors. You may have noticed how difficult it is for an electric motor to start when the network voltage is low. If the voltage applied is less than normal, the engine does not have enough starting power, it just stands there and consumes a huge starting current, which is five to seven times more than the operating current. The engine overheats very quickly and fails.

Now imagine that this is the engine of your new washing machine or a new refrigerator - you need a voltage stabilizer.

A voltage stabilizer for a private home or cottage is simply necessary to protect against constant voltage surges in the network.

To correctly increase/decrease the voltage in the network, to protect low/high voltage, you need a step-up/step-down voltage stabilizer from a reputable manufacturer. The voltage booster will be automatically selected depending on the level of voltage drop in the input power network, and in the event of an emergency change in the input voltage, all equipment will be automatically disconnected from the network.

Do I need a stabilizer?

If you don’t have anything more valuable in your home than incandescent light bulbs, you definitely don’t need a stabilizer.

It makes sense to think about buying a mains voltage stabilizer if you have at least a refrigerator or microwave oven and the mains voltage periodically drops below 190 volts.

Well, if you have “full stuffing” household appliances and the voltage periodically deviates upwards above 250 volts and/or downwards below 190 volts - to you it is imperative to protect the entire electrical network in the house with a powerful mains voltage stabilizer.

The conclusion is obvious: if the total cost of household appliances and electrical appliances in your home is several times more than the price of the most expensive voltage stabilizer, you should think about buying it.

One of them characteristic features Modern power systems are characterized by voltage fluctuations, which can not only be smooth, but also occur in the form of sharp jumps. Such situations arise under the influence of a number of factors, primarily associated with an increase in the number of consumers, significant wear and tear of cable lines, etc. Voltage can drop significantly, especially during peak periods.

It is quite possible to avoid such negative phenomena by installing a voltage stabilizer. Thus, it is possible to preserve a large number of electronic boards and other sensitive elements used in modern household devices ah and equipment.

How does the stabilizer work?

The basic principle of operation of stabilizing devices is the use of transformers in their circuits, which have parameters that can be changed and adjusted. They belong to electromagnetic devices, the main purpose of which is to change the characteristics of alternating current and voltage within specified limits.

The simplest design of a transformer is with two coils or windings wound on it, independent of each other. Alternating current is supplied to the primary coil, and a load is connected to the secondary coil. This is also where the emergence of electric current, but with different parameters. A similar condition is caused by . Voltage stabilizers use more complex transformer designs where the coils are connected.

The voltage stabilizer consists of several main parts:

A control device that monitors the input voltage and its parameters. From here all information enters the control system.
A control element with a moving part and a servo drive. After voltage is applied, it begins to move, switching connections between transformer taps. As a result, the current parameters also change. IN electronic systems control elements are installed that provide direct switching of the windings.
A part that provides continuous power supply and protection against excessive loads and short circuits. As a rule, these are thermal and magnetic releases. There is also additional protection installed against short-term exposure to high-voltage pulses.

The need for a stabilizer at home

Why do you need a voltage stabilizer? Stabilizing devices are connected together with all devices to a common electrical network. Their main task is to maintain the output voltage within specified limits, despite significant fluctuations in its parameters at the input. Stabilizers can be installed at the input, leveling the supplied power. In case of any deviations from the norm, they completely cut off the voltage supply or block the power supply to individual devices.

Therefore, before you finally decide whether a voltage stabilizer is needed in the apartment, it is recommended to take voltage measurements home network at different times of the day. This procedure should be carried out as long as possible to obtain the maximum complete information. Regulatory documents require that average values be in the range of 220-240 volts, and in Russia a range from 198 to 253 volts is allowed.

As practice shows, most receive high-quality power supply that meets generally accepted standards. However, if the measurements revealed deviations from the norms over a long period of time, you should consider using a stabilizer. This will primarily help protect household appliances that are highly sensitive to low-quality electricity.

Voltage stabilization is required for air conditioners and vacuum cleaners equipped with high-power asynchronous motors. At reduced voltage it is possible to high heat and subsequent failure. The same goes for old TVs and refrigerators, which start to overheat and buzz when the voltage drops. Incandescent lamps stop working normally and do not produce the required brightness of light. Reduced voltage negatively affects the functions of microwave ovens. The radiation power decreases, and if the parameters drop sharply, the device stops working altogether.

Voltage fluctuations negatively affect the functions of washing machines, dishwashers, electric stoves and water heaters. That is, the question of why a voltage stabilizer is needed resolves itself. Therefore, to effectively solve the problem of poor quality power supply, it is necessary to select the most suitable stabilizing device.

Main types of stabilizing devices

All stabilizers differ in design and type of execution, purpose and principle of operation. In accordance with this, they are conditionally divided into categories.

Electromechanical

Their work is based on the simplest principles. The changing input voltage affects the graphite brushes, which begin to move along the transformer winding. The output voltage changes in the same way. The very first models were equipped with a special switch with which the brushes could be moved manually. At the same time, the voltmeter was monitored to ensure that its needle was in the desired position.

IN modern devices all regulatory processes are fully automated. For this purpose, small electric motors are used to move the brushes when the input voltage changes. That is, they have all the necessary properties.

The undoubted advantages include the high efficiency of these devices, their simple design and reliable operation. The main disadvantage is low speed reactions to changing input parameters and rapid wear of mechanical parts. Therefore, such stabilizers require regular maintenance.

Electronic

They are distinguished by complete automation of all processes involved. Triacs or thyristors are used to switch between windings. The input voltage status is monitored by a microprocessor.

When the current parameters change, a command is received, after which one stage closes and the other opens. This allows you to accurately adjust the number of transformer turns involved in stabilizing the output voltage.

Electronic devices are characterized by good performance, low level noise and small size. The main disadvantage is considered to be poor resistance to loads.

Ferroresonant

The operation of these devices is based on the magnetic effect on transformer cores made of ferromagnets. They have a fairly high power rating and are equipped with special filters that reduce electromagnetic interference.

Distinctive features are high speed, accuracy of adjustments and long service life. In domestic conditions, such stabilizers are used very rarely, since they emit a continuous hum during operation.

The disadvantages include large overall dimensions and high cost.

How to choose

In most cases, owners of apartments and private houses choose relay-type devices. They have high speed switching, reliable operation and successfully compete with electronic devices.

The selection of stabilizers is carried out according to certain criteria.

Power

Selected taking into account the parameters and technical characteristics household devices and equipment that are planned to be connected through a stabilizer.

Power is calculated as follows. First, it is necessary to establish the total amount of consumer denominations based on passport data. After this, the device with the maximum starting power is determined. Next, the difference between the nominal and starting power is established. The resulting value is added to the amount of denominations established at the very beginning.

Number of phases

In apartments and most private houses, single-phase stabilizers are used. Three-phase devices are installed together with three-phase consumers or, if the entire facility is connected to an appropriate network consisting of three phases.

Such a voltage stabilizer for the home is quite expensive, so it is more economical to use three separate single-phase stabilizers.

Range

Can be working or extreme. In the first case, the possible input voltage is set, according to which the output will be 220 volts in single-phase networks and 380 volts in three-phase networks. These values are conditional with permissible errors.

In the second case, the voltage deviation at the input and its difference with normal values are determined. When the standard value is exceeded, the devices turn off, but the voltage stabilizer itself in the house remains in working order.

Accuracy

It consists in the maximum value of the permissible voltage deviation from the norm. For some inexpensive model this figure is 2-7%, and expensive devices are more accurate with a deviation of no more than 1%.

Installing stabilizers is not particularly difficult. Most of these devices can be easily installed independently and secured to the brackets included in the kit. The only technical condition is the distance to the ceiling, which should not be less than 30 cm.

Why do you need a voltage stabilizer?

Just a few years ago, when home electronics from foreign manufacturers were a rarity for domestic consumers, almost every home, as a rule, had a voltage stabilizer near the TV. Why is it needed?

We have already explained that voltage depends on the electromotive force, the potential difference. So, this electric current parameter tends to be unstable, which leads to wear of the electronics and also affects the quality of signal processing.

There can be many reasons. Firstly, the electromotive force generated by hydroelectric power plants and nuclear power plants may be non-uniform. This problem is solved at the substation, where there are powerful induction coils that filter out currents of the corresponding frequencies. However, even then, the voltage in the network is often higher or lower than the established standard.

Secondly, electrical energy consumption also affects the voltage level in the network. As a rule, in the vicinity of industrial enterprises, hospitals, and commercial establishments, where a lot of electrical energy is consumed, the voltage may also not meet the standard.

All this negatively affects the operation of home electronics. Voltage surges cause premature wear of parts and affect the quality of signal processing.

Previously, when electronics were far from perfect, lamps were used instead of semiconductors, this problem it was difficult to decide, since the lamps took up quite a lot of space, and therefore the equipment was produced without chokes that stabilize the voltage.

To protect the equipment from power surges, it was necessary to install a socket for a fuse, designed so that it would blow out before the parts of the microcircuits overheated.

However, although these measures gave confidence that the equipment would not deteriorate from power surges, they still did not improve the operation of the equipment. Therefore, as a rule, a voltage stabilizer was also included with the TV.

The stabilizer is a device that has a voltmeter, as well as a device that regulates voltage. Depending on the device, voltage stabilization can be carried out using a compensation or parametric method. Parametric method is based on the fact that when the parameters of electricity change, the stabilizing element compensates for destabilizing factors. The simplest parametric stabilizer is a device with a choke (an induction coil that does not allow currents of certain frequencies to pass through).

Another method - compensation - is as follows. The output voltage is constantly measured, and in accordance with deviations in the parameters, the actuator is controlled, which increases or decreases the voltage. This type of stabilizers has a more complex design compared to parametric ones, is less reliable, and therefore is rarely used.

The use of a voltage stabilizer greatly facilitated the use of the equipment, although there were often cases when it did not help: as soon as one of the neighbors turned on the vacuum cleaner, so-called “snow” appeared on the TV screen, and power surges in the network were sometimes so noticeable that the arrow the voltmeter treacherously jumped up, and the TV screen blinked in confusion.

However, over time, these problems receded into the background, and the only concern of the consumer was catching a clear signal. What happened?

The lamps were replaced by semiconductors, which made it possible to assemble the equipment more compactly, resulting in freeing up space for a voltage stabilizer. Now, both domestic and imported brands of TVs have a built-in voltage stabilizer, and do not have fuses, since this is not necessary.

Over time, a voltage stabilizer has become a rarity for an ordinary apartment, and now it can only be seen in elderly people who, by some miracle, managed to keep the antediluvian “Chaika” or “Horizon” TV in full working order.

The number of electrical appliances in citizens' homes is growing every day. If previously people in the house from electrical devices If there was a refrigerator and a TV, today you can count dozens of different elements of digital and household appliances. As a result, the demand for electricity is also growing. At the same time, many people live in old houses that were built 40 or even 50 years ago. But why do you need a voltage stabilizer? It's simple. The wiring in these houses and the power lines to them are designed for low energy consumption by residents. This means that voltage drops in the electrical network cannot be ruled out. Even in large cities there are similar problems, but in villages and small towns the situation is appalling.

Why do you need a voltage stabilizer?

Household and digital appliances (in most cases) cannot boast of resistance to power surges in the network. Any drop or sharp increase can cause breakdowns of electrical appliances (refrigerators, computers, televisions). By the way, it is household appliances (not digital) that suffer from this problem the most. IN special group Large heating electrical appliances such as boilers, which are extremely sensitive to voltage stability, are at risk.

You can avoid such situations by using a special device that can always supply a stable voltage to the home’s electrical network. That's what a voltage stabilizer is for.

Who doesn't need this device?

Not all people need it, because in most Russian cities the voltage in the network is stable. There is no point in buying this device if 230 V is constantly maintained in the house without any fluctuations in any direction. Why do you need a voltage stabilizer in this case? Even if you install it, its operation will be useless 99% of the time. Perhaps someday it will protect the TV, because in theory, changes in the network are possible.

Who needs it?

However, this thing is truly necessary for those people who suffer from unstable electricity in the house. And although in theory it is possible to sue the electricity company and compensate for damages if a refrigerator or other equipment in the house breaks down, this is difficult to do. At a minimum, you will have to record the fact of a power surge and prove that the refrigerator burned down precisely because of the poor quality of the service provided.

Benefits of using a stabilizer

Are you still wondering what a voltage stabilizer is for? When using it:

All electrical appliances in the house will be powered from the network for which they are designed. Consequently, their service life will increase and energy consumption will decrease.
All equipment in the house will be protected from power surges, and even if one occurs, computer and household appliances will not fail.

Note that powerful devices that are installed at the entrance of the electrical wiring to the house are quite expensive. Sometimes it makes sense to use a cheap and low-power stabilizer that can only power one computer, for example. This solution is often used in private homes and even offices. Also, many users are interested in whether a voltage stabilizer is needed for a gas boiler. If the voltage in the house is unstable, then this device is necessary for the boiler. The boiler automation operates from the mains, and a power surge can damage it. If this happens in winter, the heating system provided by the boiler will stop. Now you know whether a voltage stabilizer is needed for the boiler, but which one is already an urgent question.

Types of stabilizers

Output voltage stability is achieved different ways. There are dozens of options for network stability schemes, but not all are effective. On this moment The following stabilizers are sold in stores:

Step devices created on the basis of mechanical or solid-state relays - they are based on a standard transformer. Everything works simply: current is supplied to the primary winding, and the output voltage is removed from the secondary winding, the relay switches the voltage between them. Typically, the switching step is 10-15 V, which allows you to correct fluctuations of 5-7%. This is a very weak indicator, but such a scheme is cheap and widespread. Most stabilizers that are available on the market work exactly according to this scheme.
Electromechanical. A transformer is also used here, but instead of a relay, moving a brush along the winding is used as a switch of turns of the secondary winding. These devices are reliable, but are more expensive. Moreover, they have a serious drawback - a slow reaction speed. Sharp voltage surges in the network will simply not have time to be smoothed out.
Ferroresonant - these devices are very expensive and large, so they are almost never used in everyday life. These are the most reliable and accurate units, and they are used only where sensitive and expensive equipment is working.
Devices based on double current conversion. Like ferroresonant stabilizers, these stabilizers are also expensive, but also effective. Here, alternating current is converted to direct current, after which the direct current is transformed back to alternating current. This allows us to smooth out the smallest fluctuations, resulting in a stable voltage at the output.

What should you choose?

Speaking about what kind of household appliances are needed, we can only recommend choosing electromechanical stabilizers. Stepped ones will also work, but they are only effective when the voltage is only slightly unstable. Therefore, it is best to focus on more expensive but effective electromechanical devices. As for ferroresonant stabilizers or double current conversion devices, they are very expensive and often unavailable.

Conclusion

Now you know what voltage stabilizer is needed for a refrigerator or other household appliances. Finally, it is appropriate to warn you against low-quality Chinese stabilizers, which only create the appearance of working. It should be understood that this device must be extremely reliable and of high quality, because its operation determines how efficiently expensive digital and household appliances in the house will work and how long they will last. A stabilizer is a must for homes in which there is a change in voltage in the electrical network at least once a month. You need to complain about this and get the electricity company to resolve the issue, and if the equipment is damaged, you even need to sue it. But it is much easier and cheaper to buy a stabilizer.

Like any narrow-profile complex device, a voltage stabilizer acts as a source of a large number of myths and misconceptions. In fact, it will be quite difficult for a non-specialist to choose such a device, but anyone who wants to purchase a stabilizer for their home should understand the principle of its operation and the meaning of the main parameters.

Hearing the name “voltage stabilizer,” people who do not understand electrical engineering decide that this device was created to cope with any problems in the electrical network, that is, power surges, short circuits, and so on. In fact, this mysterious device only supports network parameters within the framework of GOST. That is why it makes practically no sense to choose a voltage stabilizer for an apartment, since there are almost no significant deviations from the norm in urban electrical networks. Few people know that the outlet can have not only 220 volts, but from 198 to 244, and this is the norm. Wiring and equipment can burn out only after 250 volts.

But for country house or giving such a useful device is almost a necessity if you do not want to change the wiring and equipment after every thunderstorm or short circuit at the substation. And if you consider that short circuits are the cause of fires, then it becomes clear that you cannot do without the described device.

The average voltage stabilizer cannot:

correct the shape of the input voltage signal and straighten the sinusoid;
filter interference at high and low frequencies, this is a function of a specialized filter, but not a stabilizer;
fully protected against short circuits.

So why choose a voltage stabilizer at all? - you ask. It's simple, this device can adjust the network voltage, raising it when the readings are too low and lowering it when the readings are too high. In addition, if the voltage surge is too sharp, the gadget turns off the power to electrical appliances. This is quite enough to ensure that sensitive electronics do not burn out, and you do not have to shell out a tidy sum for repairs or replacements.

How to choose a voltage stabilizer for your home: types of devices

Before you begin to sort through the individual characteristics and parameters of stabilizers in general, you need to make a reservation that the device can be network and backbone. The network type is a kind of adapter between an electrical appliance and an outlet, connecting directly to the latter. The main one, as the name suggests, connects to the electrical main and protects absolutely all electrical appliances in the house. Buying the first option makes sense if you are worried about some specific equipment, for example, a home PC, the second - if the voltage jumps frequently and everything needs protection, even light bulbs.

There are three main types of stabilizers:

Relays, also known as step ones, are the most popular and budget-friendly option. Under the body of this option there is an automatic relay that analyzes the incoming and outgoing voltage and lowers or increases it to the desired level. Besides affordable price, the advantages of this option include its compact size, the ability to work both in frost of -20 degrees and in forty-degree heat and quiet operation. The only disadvantage directly follows from the principle of operation - the voltage is stabilized by switching between different relays, and during this the lights may blink. If you are not bothered by the atmosphere of a horror film that sometimes arises from this feature, then you can safely take this particular type.
Electronic or thyristor - the semiconductors of this device can change their conductivity about a hundred times per second, if that tells you anything. If we switch to human language, then such a stabilizer has greater voltage settings compared to the previous version, while there are no delays and power is retained, so you can forget about flashing lights. Cons: high price and size. This option is good for a private home with a lot of expensive and sensitive electrical equipment.
Electromechanical, or servo-drive, can be both network and main, and the range of incoming voltages is from 130 to 260 volts, that is, this option will insure the equipment even in the event of very serious surges. In addition, such a stabilizer can withstand overloads, cuts off some interference and boasts good power. The fly in the ointment is that the device does not work in cold weather and the more noisy it is during operation, the higher the power. The response is slower than electronic ones.

To summarize, we can say that electronic stabilizers are the most powerful and reliable, but also the most expensive; electromechanical stabilizers are cheaper, but cannot boast such high characteristics. The golden mean is relay models, which is why they are most often chosen to protect electrical appliances.

How to choose a voltage stabilizer: main characteristics

Of course, the defining characteristic that you need to look at first when choosing a gadget is its power. It is very simple to calculate - you need to sum up the power of all electrical appliances connected to the network. But here it is worth considering two nuances. Firstly, if we are not talking about a table lamp or radio, but about a pumping station or machine, that is, devices with high starting currents, the power reserve must be at least three times greater than the sum of the powers. Secondly, even if only light bulbs are connected to the network, it is worth taking a device with at least a 20% power reserve. What if you want to plug in your laptop and a power surge occurs? Therefore, there should always be a reserve.

The second important parameter is phasing. The phase pattern of the device is selected according to the number of phases in the network, that is, single-phase for a network with one phase of 220 volts, and three-phase for a network of 380 volts. The three-phase option is significantly more expensive, therefore, if devices for one phase are connected to a network with three phases, then you can cheat and install three single-phase stabilizers - one for each phase. It will be more profitable.

Other important parameters include the following:

active load - the load that devices that provide light or heat put on the network. An iron, a heater, an electric hob and even a light bulb have active loads. It is measured in kilowatts and summed up when choosing a stabilizer;
reactive load - load from inductive and capacitive devices, that is, from electric motors and other similar devices. If you need to calculate the total power of such an electrical appliance, then to do this you need to sum up the active and reactive;
voltage range - the larger it is, the more reliable, but it doesn’t always make sense to overpay when buying a model with the widest range. This is especially true if we are talking about a more or less stable power grid. To understand what range you need, just measure the voltage in the network for several days in a row a couple of times a day. By the way, it is also worth considering that on some models the input voltage range and the maximum range are indicated. The second numbers are threshold values, after overcoming which the stabilizer simply turns off the power to electrical appliances;
accuracy - the maximum difference between the outgoing voltage and the golden 220 volts. Acceptable level The accuracy is plus or minus 7% of the nominal value, but the lights begin to blink if the accuracy is above 3%. The higher the accuracy, the less noticeable the voltage surges are, to put it simply;
type of installation – stabilizers are divided into wall and floor. The first ones are mounted on the wall, the second ones are placed on the floor. When choosing the type of installation of the device, it is worth considering that damp, dusty or dirty places are not the best choice for a device that uses electricity. And electromechanical models also do not tolerate frost, so you should not install them outside or simply in an unheated room.

An interesting, but optional feature that can be taken into account when choosing a voltage stabilizer for a summer house or home is the presence of a display. It displays input and output voltage, load and other data that will be completely useless to you if you are not versed in electrical engineering.

By the way, if you bought a voltage stabilizer, then you should not become paranoid and connect absolutely all electrical appliances to it. The refrigerator, TV, computer, telephone and light bulbs need constant voltage for stable operation, but the heater works normally even during power surges. Moreover, if you connect a powerful device such as an electric welding machine to the device, it can trigger the protection and cut off the current in principle. If you need to protect, for example, only a refrigerator with a TV, then the optimal solution would be to buy two network stabilizers instead of one main one.

How to choose the right voltage stabilizer: useful tips

When choosing a device, there are a number of small and non-obvious nuances that are worth considering and which can make your life much easier:

a power of 10-15 kW is almost always enough for a home, unless, of course, you are a “gadget maniac” who has five TVs and three refrigerators in the house or the owner of a house with powerful heating appliances, electric pumps and pumps;
Peak load on the power grid is observed in the morning and evening, so power measurements need to be taken at this time;
The network in the house can be low-voltage or amplitude; the voltage in the first is stabilized using a conventional household stabilizer, in the second - not. An amplitude network requires a special wide-range device;
Only 2% of electrical equipment in the world needs precise stabilization, the rest works normally in the range from 198 to 244 volts;
some cheap, low-quality models can lose up to half their power during operation, so you shouldn’t save;
European and Chinese electrical power is measured in volt-amperes (kVA) rather than kilowatts (kW). 10 kW is 0.7 times more than 10 kVA;
For a heating boiler, only an electronic version of the stabilizer is needed.

If you take all these points into account, choosing a model will be much easier. And if you are not at all versed in electrical engineering, then you can and should take the help of a professional electrician or at least ask for advice on thematic forums.

The best manufacturers and models

To understand which stabilizers are trustworthy and which are not, you need to at least superficially navigate the companies and models. Thus, the world leader in the production of such devices is the Italian company Ortea. All of its products withstand frost well and boast great power, accuracy and other advantages. The most popular model from the company is Ortea Vega 1.

Bastion is a Russian company that promises a lifetime warranty on some of its models. The development, production of all parts and assembly of devices takes place entirely on the territory of the Russian Federation, hence the relatively low price. If you are interested in this brand, then pay attention to the Teplocom ST-555 model.

Resanta– Chinese-made stabilizers, available in three-phase and single-phase, of varying power and accuracy, in general, satisfy a variety of needs.

If we consider specific models, then based on a number of characteristics the following can be distinguished:

QUATTRO ELEMENTI STABILIA 1000 is the best low-power model for household appliances, and at the same time, it is inexpensive. Minus – low accuracy;
QUATTRO ELEMENTI STABILIA 12000 is the best high-power model, whose stabilization accuracy is also, alas, lame;
PROGRESS 8000TR is the 2017 leader in terms of accuracy. It is noisy during operation, but with a stabilization error of only 3% this is not critical;
RUCELF SDWII-12000-L is the best electromechanical model and, in principle, one of the best stabilizers. Protects not only from power surges, but also from short circuit, overheating and interference. It is not cheap, but the reliability is high.

It is convenient to compare prices for this equipment