DIY repair stabilizer resant 10 kW

In detail: do-it-yourself repair of a 10 kW resant stabilizer from a real master for the site my.housecope.com.

Graphic display of the main operating modes of voltage stabilizers

In one of the previous articles, the main types of voltage stabilizers were described, as well as instructions on how to connect them to the network with your own hands. This material introduces the main malfunctions of voltage stabilization devices and the possibility of their self-repair.

It must be remembered that a stabilizer of any type is a complex electrical or electromechanical device with many components inside, therefore, in order to repair it with your own hands, you must have a sufficiently deep knowledge of radio engineering. Repairing a voltage regulator also requires appropriate measuring equipment and tools.

Sophisticated stabilizer design

All voltage stabilization devices have a protection system that checks the input and output parameters for compliance with the rated value and operating conditions. Each stabilizer has its own protective complex, but several common ones can be distinguished. parameters, going beyond which will not allow the stabilizer to work:

Rated input voltage (stabilization limits);
Output voltage matching;
Excess load current;
Temperature range of components;
Various signals from indoor units.

The list of control parameters of the stabilizers specified in the technical characteristics

It is necessary to check whether there is a short circuit in the load, the input voltage, the temperature conditions of operation and study the meaning of the error codes displayed on the displays.

Video (click to play).

The most difficult thing is to find a breakdown in the stabilizer on triac keys, which are controlled by complex electronics. For repairs, you must have a diagram of the device, measuring instruments, including an oscilloscope. According to the given oscillograms at the control points, a malfunction is found in the structural module of the stabilizer, after which it is necessary to check each radio component in the defective unit.

The main nodes of the triac stabilizer

In relay stabilizers, the most common cause of failure is the relay that switches the transformer windings. Due to frequent switching, the relay contacts can burn out, jam, or the coil itself can burn out. If the output voltage fails or an error message appears, check all relays.

Power switches of the relay stabilizer

For a master unfamiliar with electronics, it will be easiest to fix an electromechanical (servo) stabilizer - its operation and reaction to voltage changes can be seen with the naked eye immediately after removing the protective casing. Due to the relative simplicity of the design and high stabilization accuracy, these stabilizers are very common - the most popular brands are Luxeon, Rucelf, Resanta.

Resant stabilizer, power 5 kW

If the stabilizer transformer began to warm up without a noticeable load, then a short circuit, called interturn, may have occurred between the turns. But, given the specifics of the operation of these devices, in which the terminals of the autotransformer or the secondary winding of the transformer are switched all the time in order to adjust the output voltage to the required value, we can conclude that the short circuit is somewhere in the switches.

Switching unit for relay stabilizer

In relay stabilizers (SVEN, Luxeon, Resanta) one of the relays can jam, and several turns of the transformer will be short-circuited... A similar situation can arise in thyristor (triac) stabilizers - one of the keys may fail and will "short" the output windings. The short-circuit voltage between turns, even with an adjustment step of 1-2V, will be enough to overheat the transformer.

Switching unit of the stabilizer on triacs

It is necessary to check the triac keys to exclude this breakdown. The thyristor or triac is checked by a tester - between the control electrode and the cathode, the resistance during forward and reverse measurements should be the same, and between the anode and cathode, it should tend to infinity. This check does not always guarantee reliability, therefore, to guarantee it is necessary to assemble a small measuring circuit, as shown in the video:

In servo-driven stabilizers, the windings do not switch, but adjacent turns can also be closed due to a mixture of soot, dust and graphite sawdust clogged in the space between the turns. Therefore, servo-driven stabilizers such as Resanta and others require periodic preventive cleaning of contaminated contact pads.

Many users have noticed that the rate of wear and contamination of the contacts of servo stabilizers depends on the operating environment, in particular, on dust and moisture. Therefore, the craftsmen came up with a way to modify Resant's stabilizers by installing a fan from a computer processor (cooler) opposite the most frequently used autotransformer sector.

Miniature fan for servo stabilizer modification

A constantly running fan prevents dust from settling on the contact pads, preventing contamination and wear by removing abrasive particles from the working area. In addition to cleaning the contact surfaces, the fan installed in the Resant stabilizer will also contribute to better cooling of the autotransformer.

Repair of stabilizers with a servo drive, such as Resanta, should begin with an inspection of the working contact area of the autotransformer.

Carefully inspect the most worn areas of the contact turns

If the Resant's stabilizer was stored in a humid environment after a long time of operation, then the exposed unprotected copper contact pads could oxidize, which prevents the contact slider from contacting. Dust accumulated during downtime due to sparking can be flammable. Briefly about the prevention of electromechanical stabilizers and a demonstration of the servo drive in the video:

It is best to remove the pin slider from the servo shaft first. After that, you should use fine sandpaper to clean the contact pads to a metallic sheen. It is better to clean the auto-transformer contacts with a regular eraser. Then you need to carefully remove the accumulated sawdust and abrasive particles with a brush. Image - DIY repair stabilizer resant 10 kW

The device of the contact assembly of the servo stabilizer

The next step in repairing the servo stabilizer will be inspection, cleaning and possible replacement of the contact graphite brush. During operation, this brush heats up due to the currents flowing through it. But even more heating occurs due to poor contact between the brush and the contact plates of the autotransformer. Due to the increased heating and arcing during the movement of the slider, the brush burns out even more, thereby contaminating the contact pads and the gaps between them.

Severe contamination of the contacting turns of the autotransformer

Thus, the acceleration of pollution is gaining an avalanche-like character, which leads to rapid wear of the autotransformer contacts and burnout of the contact brush, after which the stabilizer will stop supplying voltage.Depending on the protection system in the servo-driven stabilization devices from the Resanta company, or from other manufacturers, in the event of a break in the output voltage, the protective automatics must be triggered.

Contactor - power element of protective automation

That is why it is so important prevention servo stabilizers. Often, Resant's repair ends with cleaning the contacts and replacing the contact brush. But, sometimes in servo stabilizers the servo itself fails. Servo failure can be caused by wear on the gearbox, burned out motor, or lack of voltage. Having taken out the motor together with the gearbox, it is necessary to check the mechanism by turning the shaft.

The electronic control board of any type of stabilizer contains many components, including microcircuits, which cannot be tested without special equipment. But it's worth it carefully inspect the board itself and check the components on it for traces of high temperature.Sophisticated electronic circuit board of the relay stabilizerOverheated resistors are the first to "catch the eye" and sometimes carbonize to such a state that it is impossible to recognize their markings - you will have to study the stabilizer circuit. Overheating of the resistors indicates a breakdown in other elements of the circuit - most often in power transistor switches. A close examination of the transistors can reveal blackening from overheating, and even mechanical cracks. Image - DIY repair stabilizer resant 10 kW

An example of a relatively simple relay stabilizer circuit

The cause of a malfunction of any circuit can be a breakdown in the capacitor. Very often electrolytic capacitors swell, which is why they differ significantly in shape from other capacitors. But the breakdown of a capacitor can not always be determined by its swelling - the electrolyte inside can dry out, from which it will lose its electrical conductivity.

An illustrative example of a blowing capacitor

On the board itself, traces of the impact of freelance overcurrents can also be seen - some tracks may burn, and the contacts may be soldered off, or close together due to the spreading molten solder heated by large currents. In addition, traces of strong heating of parts may remain on the board - from a change in shade to charring of the PCB.

An example of a burned-out track on the board

Visual inspection of the defective module can tell the technician in which direction to diagnose. But, as a rule, the repair of electronic boards of stabilizers is not limited to replacing clearly damaged parts and requires additional checking of various components using special equipment. Therefore, if the continuity of the power transistors and other elements did not reveal the cause of the breakdown, it is better to take the electronic board to the workshop.

Resanta voltage stabilizers can be found in many apartments in our country, which is understandable. This is due to the fact that such units make it possible to normalize the operation of all electrical appliances that are present at home. In other words, they allow you to save quite expensive equipment in the event of an overload in the network, or in case of voltage surges, thereby significantly extending the operational life of all electrical equipment.However, the operation of the voltage stabilizer also carries the risk of certain breakdowns, the only way out of which is timely repair. There may be several reasons for this - from improper operation to natural causes of breakdown, i.e. long service life.To avoid this, you must exactly follow the instructions that come with the kit, which allows you to significantly extend the service life of the unit in the correct mode of operation. If, nevertheless, a breakdown did happen, then you need to know what methods you need to properly carry out repairs with your own hands, so as not to further aggravate the situation.In this article, we will look at the main malfunctions, as well as ways to eliminate them in a timely manner.This video shows the Resant's stabilizer with a malfunction

The constructive structure of the Resant voltage stabilizer is as follows:

automatic transformer;
the electronic unit;
voltmeter;
a control that is responsible for starting and disconnecting some windings.

This manufacturer produces many different types of stabilizers, therefore, these organs for connecting the windings will differ. We will talk about all these nuances a little later, during the consideration of the repair procedure.

In this design, the decisive factor is the electronic unit, which carries out the general control of the entire system of the unit. He is responsible for the operation of the voltmeter, and also receives information about the power of the input voltage. Then, the block compares the obtained values with the optimal ones, determining the next action, i.e. whether you need to add a few volts or, on the contrary, subtract a certain amount.

Further, along the chain, there is a determination of the necessary windings - which of them need to be started and which ones to be disabled. Then, the electronic unit performs one of these actions, after which all electrical appliances in the apartment receive a stable current.

Of course, the stabilization process itself can be slightly different, depending on the type of device produced.

This difference applies to the types of windings, as well as the methods of starting and disconnecting them. Today, the Resanta company produces two types of these stabilizers:

Electromechanical type.
Relay.

Accordingly, their repair will be somewhat different.

Let's start our consideration with stabilizers of the electromechanical type. In its design there is a servo drive, which starts and turns off the windings in the device.

The servo itself consists of a motor on which an electrical contact (brush) is located. When the armature of this motor moves, accordingly, this brush also rotates, constantly contacting with copper windings. The width of this brush allows for a complete wrap-around of the entire winding, which allows the phase not to be lost.

In order for the brush to move in a given direction with the desired characteristics, an error voltage arises in the device. Then, this voltage value rises. Then it is transmitted to the engine, which makes the armature rotate in the optimal direction. Accordingly, the brush also moves, like the armature, in the same predetermined direction. In this case, direct contact with the windings is carried out.

The error voltage value will be proportional to the value formed by the difference between the real voltage value at the input and the value that should be there. This signal can have one of two polarities, each of which specifies a certain direction of movement. Below is a diagram of a similar voltage regulator:

Read also: DIY aton boiler repair

But, first, let's talk about the general structure and principle of operation of devices of this brand.

Like all voltage stabilizers and normalizers of the "Resanta" brand, they consist of:

automatic transformer.
electronic unit.
voltmeter.
an element that connects / disconnects certain windings.

Considering that the manufacturer produces various types of stabilizers, the elements for connecting the windings are different. We will note about them a little below, namely when we consider the features of the operation and repair of each type of normalizer from a Latvian manufacturer.

The electronic unit of any stabilizer of the company "Resanta" controls the entire operation of the device. It controls the operation of the voltmeter and receives information about the input voltage level. Then he compares this voltage with the normalized one and determines how many volts to add or subtract.

After that, it is determined which stabilizer windings need to be connected or disconnected. When this information is known, the electronic unit connects / disconnects the necessary windings using a relay or servo drive and our electrical appliances receive a normalized current.

This principle of current stabilization is inherent in each voltage stabilizer from the "Resanta" company. However, the stabilization process in various models of the company differs. They are due to the fact that the connection / disconnection of the transformer windings occurs in different ways.

Within the walls of the company, two types of stabilizers are produced:

And, of course, the repair of each of them has its own characteristics.

We will first look at an electromechanical normalizer. The device of this voltage stabilizer from the "Resanta" company provides for the presence of such an element as a servo drive. Actually, thanks to him, the switching of various windings of the automatic transformer is carried out.

The switching of these windings is smooth and the result is a precise control of the output voltage.

How does this smooth adjustment take place? A servo is a motor and a brush (electrical contact) that is attached to the armature of the motor. When this anchor turns, the brush also moves.She is constantly in contact with the copper windings of the transformer.

In fact, she slides over them. It is wide enough to connect two windings at the same time. As a result, there is no phase loss at the output.

In order for the brush to move in a certain direction and by a certain amount, an error voltage is created in the normalizer. Further, thanks to the operational amplifier and the transistor output stage (it is a power amplifier), this voltage is amplified.

After that, it is fed to the engine and makes the armature spin in a certain direction.

The brush moves in this direction, which is in contact with the windings. The error voltage is proportional to the difference between the number of volts at the input and the required number of volts.

The error signal can have one of two polarities, and as a result, each polarity causes the motor axis to rotate in a specific direction. These are the features of the operation of the electromechanical normalizer.

Note that many people buy a 10KV electromechanical regulator. Therefore, possible malfunctions and breakdowns of this type of voltage stabilizer from the "Resanta" company will be considered on this model. Below is its wiring diagram.

Rice. 1. Wiring diagram of the ASN-10000/1-EM stabilizer.

It is worth paying attention to the fact that the general structure of all normalizers of this type is similar. The differences lie in the individual elements of the models with different power levels.

From the above-described principle of operation of the electromechanical stabilizer, it becomes clear that when there is a change in the current in the mains, there is a simultaneous rotation of the motor armature and the movement of the graphite brush.

The constant movement of the servo is the main weakness of the electromechanical device. Why? Because as a result of friction of the brush against the coil turns, excessive heating of both the brush and the turns under it occurs.

In addition, friction causes brush wear and contamination of the copper wires. The latter cause sparks.

Considering the fact that in our power lines the current changes very often, the servo drive moves with the same frequency. Such frequent rotation causes the failure of the engine itself.

A notable feature is that engine failure causes other parts to fail. So, there is a possibility of failure of the output stage of the engine control.

Resanta specialists assemble this stage based on a pair of transistors Q2 TIP41C and Q1 TIP42C. When these transistors burn out, the resistors R45 and R46 also burn out.

They are the components of the collector circuit of the above transistors. R45 and R46 are characterized by a resistance of 10 ohms and a power of 2 watts.

When there are such malfunctions, then it is necessary to check the linear stabilizer. Its Latvian specialists assemble on the basis of a DM4 Zener diode and a Q3 TIP41C transistor.

If all these components of the electrical circuit of an electromechanical voltage stabilizer manufactured by Resanta have burned out, then in any case they need to be bought and replaced.

When the engine itself burns out, then there are two options:

Buying a new one and installing it.
An attempt to restore an old engine.

The second option makes it possible to reanimate the engine on its own, however, not for a long time. For resuscitation, it is necessary to disconnect the engine from the general circuit. After that, it must be connected to a powerful power source.

Your task is to supply current to its outputs with a constant voltage of 5 volts. In this case, the current must be between 90 and 160 mA. When such a current is applied, every small particle of "debris" burns out on the motor brushes.

Helpful hint: since the motor is of the reversible type, the polarity must be reversed when voltage is applied. This procedure is carried out two times.

After such actions, the engine will be able to work again, and the stabilizer will perform its main function. Further, according to a simple scheme, you can carry out the procedure for connecting a voltage stabilizer manufactured by Resanta.

This diagram involves connecting the input phase and neutral cables to the input phase and neutral terminals, respectively. The connection of the output wires is the same. Also, be sure to connect the ground wire.

As for the relay stabilizers from the Latvian company, other malfunctions occur during their operation. Accordingly, their repair is a different procedure.

Before considering the peculiarities of repairing the "Resant" relay normalizer, let us pay attention to the peculiarities of its operation. The relay device equalizes the current in a stepwise manner.

This is because one relay connects / disconnects a certain number of turns of the second winding. If we compare an electromechanical stabilizer, then its brush gradually comes into contact with a large number of turns.

In other words, it gradually connects the intermediate turns and stops at the desired turn. In relay devices from "Resant" all the loops are divided into groups and the output goes from each of them. Actually, this output is supplied with current when the relay is turned on.

The electrical circuit of each relay voltage stabilizer from the "Resanta" company provides for the presence of four relays, which means that the number of terminals of the second winding is also four.

The exception is the models of the SPN series. The number of relays is five.

Helpful advice: when a certain relay turns on or off, the output voltage changes by 15-20 volts, that is, there are mini voltage surges. These mini jumps are clearly visible on the lights.

For most electrical appliances, they are not scary. However, sophisticated electronic and measuring technology requires a smoother current stabilization. This should be taken into account when using any relay stabilizer.

Summarizing the above, we note that the entire process of current normalization is accompanied by the constant operation of the relay. Actually, this mechanical component is the weakest point. During operation, it can both burn out and stick.

In the event that the relay contacts fail, transistor keys can also break. Depending on the model, these keys can be collected on different transistors. So, in the SPN-9000 model, these keys are assembled on the basis of 2SD882 transistors.

At the heart of the transistor switches of the ASN-5000/1-Ts model (its diagram is given below) are the D882P transistors. All of these transistors are manufactured by NEC.

Rice. 2. Diagram of the ASN-5000/1-Ts stabilizer.

In cases where these transistors and relays fail, they are completely replaced. Such spare parts for the aforementioned models of voltage stabilizers manufactured by Resanta can be found in many stores.

You can also try to restore worn relay contacts. This procedure begins by removing the relay cover. Then they begin to remove the movable contact. This contact must be released from the spring.

Next, they take zero-grade sandpaper and clean this contact from all burnt particles. The same cleaning procedure must be done with respect to the upper and lower contacts.

At the end, all contacts are processed with Galosha gasoline and the relay is assembled. When the relay is assembled, you should check the 2SD882 or D882P transistors, or others (this depends on the modification).

They are soldered (you need to have a soldering iron) and the integrity of the transitions is checked. If the junctions are not holistic, you need to take new transistors.

After

After the completion of the repair work, it is necessary to diagnose the operation of the stabilization device. To do this, use LATR, to which the stabilizer is connected.Then, with the help of LATR, the voltage is changed and the operation of the stabilization device is monitored. A light bulb is used as a load.

After verification, you can connect to the public network. If you do not know how to connect a relay voltage stabilizer made within the walls of the "Resanta" company, then it is worth remembering that this procedure is the same as for an electromechanical normalizer. We have already written about it.

JAKEC capacitor set

It is worth noting that a breakdown of a relay may not be the only malfunction that occurs in a relay normalizer from a Latvian company. In some cases, a periodic defect was observed in the SPN-9000 stabilizer.

An external sign of this defect was a chaotic display of display segments that were turned on. At the same time, a chaotic switching on of the relay was observed.

The reason for this lies in the cold soldering of the XTA1 quartz resonator, which has an operating frequency of 8 megahertz. This soldering causes the microcontroller U2 to malfunction.

To solve the problem, you need to evaporate this resonator, clean its terminals with zero sandpaper, carry out a high-quality soldering and put it back.

Experts also recommend checking the electrolytic capacitors located on the controller board. This must be done for the reason that the company uses capacitors from the manufacturer JAKEC. These capacitors are not of high quality. During their verification, capacitance and ESR measurements are carried out.

«Chronic» voltage instability has become almost the norm in private homes. During peak loads, especially in winter, the mains voltage drops to a critical minimum. These negative factors force the consumer to purchase mains voltage stabilizers, which sometimes fail. In this article, the author shares his experience in repairing voltage stabilizers «Resanta».

The stabilizer market is represented by a wide range of brands: Progress, Shtil, WUSLEY SASSIN, Resanta, Energia, SPNB, Solby, SHIELD, TSS, Caliber, Lider, STEM, STS, Ortea, Volter, Voltguard , Vega, Pilot, Legat, APC, FNEX, Orion, CCK.

Resanta is a popular trademark of the largest Latvian manufacturer of electrical equipment. Let's consider the repair of two models of stabilizers of the company "Resanta": ASN-10000/1-EM with a capacity of 10 kW and SPN-9000 with a capacity of 9 kW. Both models are in demand in the consumer market for their technical characteristics, and can be used in an apartment, house and small office. The first model belongs to the type of electromechanical stabilizers, the second - to the type of electronic stabilizers with digital indication. Both stabilizers belong to the class of single-phase stabilizers. They differ in how they work, but have their own strengths and weaknesses.

Repair of the ASN-10000/1-EM electromechanical stabilizer

A schematic diagram of the ASN-10000/1-EM stabilizer is shown in fig. 1, the printed circuit board of the controller of this stabilizer is on photo 1.

The principle of operation of electromechanical stabilizers is based on smooth and precise regulation of the output voltage. The voltage change occurs due to the sliding of the electrical contact along the winding of the autotransformer using an electric drive. An error voltage is generated in the stabilizer, which is amplified by an operational amplifier and a transistor output stage (power amplifier), and then it is fed to the motor. Depending on the polarity of the error signal, the motor axis rotates in one direction or the other. A slider is fixed on the motor axis, which moves along the winding of the autotransformer, thereby normalizing the output voltage.

Let us consider one typical malfunction that occurs during the operation of electromechanical stabilizers, using the example of ASN-10000/1-EM of the "Resanta" company and methods for its elimination.

There is no stabilization of the output voltage. The output voltage level can be different and remain unchanged. Overheated components smell. The "Achilles heel" of electromechanical stabilizers is a reversible motor. The regulator controller constantly monitors the output voltage level. As a result, the rotor of the motor is in almost constant rotation, which leads to premature wear of the motor. After stopping the engine, the motor control output stage, assembled on a complementary pair of transistors Q1 TIP42C and Q2 TIP41C, may fail. (fig. 1). In addition to these transistors, the resistors R45 and R46, included in their collector circuit, burn out from overheating. Their resistance is 10 ohms, and the power is 2 watts. It will not be superfluous to check also the linear stabilizer assembled on the Q3 TIP41C transistor and the DM4 zener diode.

Rice. 1. Diagram of the stabilizer of the Resant ASN-10000/1-EM

Of course, a worn out engine requires replacement, but if replacement is impossible, you can try to restore it. One of the simplest ways to resuscitate a faulty engine is as follows:

disconnect the motor from the circuit;
supply its terminals with a constant voltage of 5 V from a powerful power source, for example, from an ATX computer power supply.

In this case, small particles of "debris" are annealed on the engine brushes.

The normal current consumption of the motor must be between 90 ... 160 mA.

Since the motor is reversible, the voltage must be applied to the motor twice with reverse polarity. After these simple manipulations, the engine's performance is temporarily restored.

Repair of electronic stabilizers

The principle of operation of electronic stabilizers is based on discrete (step) regulation of the output voltage. Voltage stabilization in automatic mode is provided by a microprocessor. The autotransformer taps are switched abruptly using powerful electrical relays controlled by transistor switches. The switching resolution of various stabilizers ranges from 5 to 20 V. Accordingly, the lower this value, the more stable the output voltage.

Consider two typical malfunctions that occur during the operation of electronic stabilizers, using the SPN-9000 as an example. Stabilization does not work when the input voltage drops from

220V before

170V, or when raising it higher

220 V. At the same time, in both cases of lack of stabilization, the output voltage changes synchronously with the input. Sometimes, when the stabilizer is turned on, it knocks out the plugs, that is, the short circuit protection is triggered. The main "disease" of electronic voltage stabilizers is burning and sticking of relay contacts (photo 2).

Due to faulty relays, keys assembled on NEC 2SD882 transistors fail. Relays (all five) are replaced with new ones or restored. To do this, remove the covers from the relay, then remove the movable contact, release it from the spring and carefully clean all the relay contacts (upper, movable and lower) with the help of "zero" emery paper. Then, all contacts are finally cleaned with Galosha gasoline and the relay is assembled in the reverse order. Then they solder all five 2SD882 transistors and check the integrity of the transitions. If necessary, replace the transistors with new ones.

More recently, it was necessary to repair a voltage regulator with a periodic defect. Outwardly, this defect manifested itself as chaotic display of switching on display segments, accompanied by chaotic actuation of the relay. This defect was codenamed "blizzard". It arises from the cold soldering of the XTA1 quartz resonator with an operating frequency of 8 MHz. It is clear that because of this the microcontroller U2 will not work normally (the marking is sealed with a label). It should be noted that the conclusions of the problematic quartz resonator are poorly serviced.Therefore, it is best to solder it out, clean its terminals with zero-grade sandpaper, then irradiate them with high quality, solder and install the XTA1 in place.

When repairing the stabilizer, it will not be superfluous to check all the electrolytic capacitors on the controller board. The fact is that the manufacturer uses cheap JAKEC brand capacitors of extremely low quality. They measure not only their capacity, but also ESR. At this, the repair of the voltage stabilizer can be considered complete. Then the voltage regulator is turned on and its performance is checked.

Recommendations

To check the operability, as well as when diagnosing voltage stabilizers, the input voltage must be supplied through the LATR. This will allow you to vary the input voltage within a wide range.

Incandescent lamps can be used as a load.

When diagnosing voltage stabilizers, you must take precautions.

During operation, voltage stabilizers must be disconnected before a thunderstorm.

Voltage stabilizers require regular maintenance to maintain their working life. Therefore, maintenance of voltage stabilizers is required at least once every six months. Failure to do so may result in damage.

Video (click to play).