What protective devices can be used against overvoltages. Methods of protection against overvoltage in apartments and private houses

Currently, the issue of a stable voltage in the electrical network is quite acute. Network organizations are in no hurry to reconstruct and modernize power lines, substations and transformers. Meanwhile, the situation is only getting worse, so voltage fluctuations in our networks are a fairly common occurrence.

Update 11/11/2018.
For those who doubt the installation of a relay to protect against voltage surges for their home or believe in the quality of construction and installation work in modern new buildings. Below is a screenshot of one of the latest.

According to GOST 29322-92 voltage in the power grid of our country should be within 230 V at one phase and 400 V between phases. But if you live in a rural area or near a city, then problems with constant voltage levels are very high, and in the city itself this cannot be ruled out, especially in older housing stock. Voltage surges have a very detrimental effect on electrical appliances in the house. For example, due to low voltage, a refrigerator or air conditioner may burn out (the compressor will not start and overheat), the power of the microwave is greatly reduced, and incandescent lamps glow dimly. Well, high voltage will simply “kill” your household appliances. I'm sure many have heard about "zero burnout" in high-rise buildings, and how entire entrances are taken to workshops to repair household appliances.

The reasons for voltage fluctuations in the network are different:

• Shorting one of the phases to neutral, as a result there will be 380 Volts in the outlet;
• Burnout (break) of zero, if you have a low load at this time, then the voltage will also tend to 380 V;
• Uneven distribution of load across phases (misalignment), as a result, at the most loaded phase, the voltage decreases, and if a refrigerator and air conditioners are connected to it, then there is a high probability that they will break;

Example video showing the operation of a voltage relay

Special devices - voltage control relays - help solve the problem of voltage surges in networks. The principle of operation of such relays is quite simple, there is an “electronic unit” that monitors that the voltage is within the limits specified by the settings and, if there are deviations, signals the release (power section), which turns off the network. All household voltage control relays turn on automatically after a certain time. For ordinary consumers, a delay of a few seconds is sufficient, but for refrigerators and air conditioners with compressors a delay of several minutes is needed.

Voltage control relays are available in single-phase and three-phase types. Single-phase voltage relays disconnect one phase, while three-phase voltage relays disconnect all three phases at the same time. When using a three-phase connection at home, single-phase voltage relays should be used so that voltage fluctuations on one phase do not lead to the shutdown of other phases. Three-phase voltage relays are used to protect motors and other three-phase consumers.

I divide surge protection devices into three types: UZM-51M from Meander, Zubr from Electronics and all the others. I am not imposing anything on anyone - this is my personal opinion.

Voltage relay Zubr (Rbuz)

This device is designed to protect against voltage surges (zero burnout). BISON is produced in Donetsk.

I will note the features of this voltage relay.

Voltage indication on the device - shows the voltage value in real time. This is quite convenient and necessary for assessing the voltage situation in the network. The reading error is low, the difference relative to the Fluke 87 high-precision multimeter is only 1-2 Volts.

Zubr voltage relays are produced for various rated currents: 25, 32, 40, 50 and 63A. The device, with a rated current of 63A, can withstand a current of 80A for 10 minutes.

The upper voltage value is set from 220 to 280 V in steps of 1 Volt, the lower - from 120 to 210 V. The restart time is from 3 to 600 seconds, in steps of 3 seconds.

I set the Zubr voltage relay, the maximum (upper) voltage value is 250 Volts, and the lower value is 190 Volts.

For devices with index t in the name, for example Zubr D63 t, there is thermal protection against internal overheating. Those. when the temperature of the device itself increases to 80 degrees (for example, due to heating of the contacts), it turns off.

Zubr voltage relays occupy 3 modules or 53 mm on a DIN rail and are only single-phase.

The passport and the wiring diagrams for the Zubr voltage relay do not say about current limitations, but in the old documentation it was previously indicated that no more than 0.75 of the nominal one.

Zubr voltage relay wiring diagram

Currently, manufacturers claim that the relay can be connected at its nominal value. If the rating of the Bison is less than the rating of the input circuit breaker, then you need to use a voltage relay - a contactor - in the connection diagram.

Relay warranty Voltage Zubr the manufacturer gives whole 5 years! Has very good reviews from colleagues - forum members. And just like Meander on the MasterCity forum there is a Zubra representative who is not afraid to communicate publicly. And by the way, it is indicative from the example of UZM and Zubr that representatives of manufacturers of quality products are not afraid to communicate on forums.

Video about voltage relay Zubr

Update (06/07/15). Currently, the Zubr voltage relay is sold in Russia under a different name Rbuz (the word Zubr is backwards).

This is due to the fact that in Russia the Zubr trademark is registered with another manufacturer and only the name of the relay has changed, but all the components remain the same.

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UZM-51M. The protection device is multifunctional.

Currently, UZM-51M has proven itself to be reliable and easy to connect.

UZM-51M is designed for current up to 63A, occupies 2 modules on a DIN rail (35 mm wide). In the standard version, the operating temperature of the UZM is from -20 to +55 degrees, so I do not recommend installing it in a switchboard outdoors. It is true that there is a range from -40 to +55, but I have never seen such on sale, unless you contact Meander JSC directly.The maximum setting for the upper voltage cut-off is 290 V, the lower threshold is 100 V. The restart time is set independently - this is either 10 seconds or 6 minutes. Can be used in networks with any type of grounding: TN-C, TN-S, TT or TN-C-S.

Connection diagram UZM-51M

Meander produces two more types of single-phase voltage relays - these are UZM-50M and UZM-16. The main difference between the UZM-50M and the UZM-51M is, perhaps, only that in the latter, as we know, you can set the triggering setting independently, while in the UZM-50M the setting is “hard”, the upper voltage limit is 265 V, and the lower - 170 V.

UZM-16 is designed for a current of 16A, so it is installed only on a separate electrical receiver. For example, in order not to wait 6 minutes for the UZM-51 to turn on, the refrigerator can be connected via the UZM-16, on which the turn-on delay is set to 6 minutes, and on the main UZM-51M to 10 seconds.

I set the maximum (upper) voltage value on the UZM-51M to 250 Volts, and the lower value to 180 Volts.

Meander also produces a three-phase voltage relay UZM-3-63, as I wrote above, such relays are used mainly to protect engines.

Good reliable surge protection. The UZM does not need to be connected with a contactor, as is usually done with other voltage relays. The device is manufactured in Russia. UZM warranty is 2 years. What’s important is that Meander’s representative is present on the most popular Mastercity forum, always gives advice on products, and also pays close attention to the comments of forum users, whose comments at one time helped improve the UZM-51M.

An example of installing UZM-51M in a three-phase switchboard for a country house, where UZM is installed in each phase.

Perhaps one drawback of the UZM-51M relative to other voltage relays is the lack of voltage indication. But the difference in price between the UZM and a voltage relay with a contactor allows you to buy and supply a voltmeter separately.

Voltage relay RN-111, RN-111M, RN-113 from Novatek

These voltage relays are manufactured here in Russia. As you can see from the title, Novatek offers three types of voltage relays.

RN-111 and RN-111M are practically the same device in terms of parameters; their main difference is that the RN-111M relay has a voltage indication, while RN-111 does not.

The upper voltage limit is from 230 to 280 V, the lower limit is from 160 to 220 V. The automatic restart time is from 5 to 900 seconds. These relays have a 3 year warranty.

Connection diagram for voltage relay RN-111

RN-111 is designed for small currents up to 16A or power up to 3.5 kW, but to connect a higher load, RN-111 can be switched on together with contactors (magnetic starters).

Connection diagram for voltage relay with contactor

This significantly increases the cost, since a good contactor will now cost about 4-5 thousand rubles, you will need a larger number of modules in the panel, as well as a circuit breaker to protect the contactor coil. The above diagram for connecting a voltage relay with a contactor for RN-111 is valid for any other relay, taking into account the features of its circuit.

The RN-113 relay is already more improved relative to the RN-111, the voltage ranges and AR time are the same as those of the RN-111, but the maximum current for which the RN-113 can be turned on is up to 32A or if the power is up to 7 kW.

Connection diagram for voltage relay RN-113

But I would not do this, since the contacts on the RN-113 are weak enough for a wire with a cross-section of 6 mm 2, and this is precisely the cross-section required for a 32A connection.

It is more reliable to connect RN-113 with contactors, without contactors maximum 25A. I don’t use voltage relays from Novatek in my switchboards, so I borrowed the photo from one of the electricians from the Avs1753 forum.

It looks, of course, beautiful, but such a connection takes 3-4 more modules and is twice as expensive in cost as if UZM-51M or Zubr were used.

But what happens with the RN-113 if you connect it without 32A contactors.

Unfortunately, I did not find any information about tests like the UZM-51M and Zubr on the forums.

Voltage relay TM DigiTop

Just like Zubr, these relays are produced in Donetsk. The manufacturer produces several series of devices with protection against power surges.

The V-protector series voltage relay is intended only for protection against voltage surges. Available for rated currents of 16, 20, 32, 40, 50, 63 A in a single-phase version, it has built-in thermal protection against overheating, triggered at 100 degrees. The upper threshold is from 210 to 270 V, the lower one is from 120 to 200 V. The automatic switching time is from 5 to 600 seconds. There is also a three-phase voltage relay V-protector 380, quite compact 35 mm (two modules), but the maximum current in a phase is no more than 10A.

The Protektor single-phase voltage relay has a 5-year warranty, and the three-phase relay only 2 years.

V-Protektor DigiTop voltage relay connection diagram

Digitop also produces a voltage relay and a current relay, VA-protector, combined in one device. In addition to overvoltage protection, the device also provides current (power) limitation. Available for rated currents of 32, 40, 50 and 63 A. All voltage parameters are the same as those of the V-protector. Based on the rated and maximum current, VA controls the load and, if the rated current is exceeded, turns off the network after 10 minutes, and the maximum - after 0.04 seconds. The device display shows both voltage and current. VA-protector warranty is 2 years.

Well, the most advanced of the series of voltage relays from TM DigiTop is the MP-63 multifunctional relay. Actually, everything is the same as with the previous VA-protektor, only MP-63 shows, in addition to current and voltage, also active power.

This MP-63 relay and V-protector were independently tested by members of the forum, the reviews are average.

I tried to cover in my article the most common surge protection devices. Of course, there are still manufacturers of devices for this type of protection, but there is very little information about their use.

Thank you for your attention.

Fuses are traditionally used to protect electronic equipment. Typically, they use thin, uninsulated conductors with a calibrated cross-section, designed for a given burnout current. These devices work most reliably in high-voltage alternating current circuits. As the operating voltage decreases, the efficiency of their use decreases. This is due to the fact that when a thin wire burns out in an alternating current circuit, an arc appears, spraying the conductor. The maximum voltage at which such an arc can occur is considered to be 30...35 6. With a low-voltage supply, the conductor simply melts. This process takes a longer time, which in some cases does not save modern semiconductor devices from damage.
However, fuses are still widely used in low-voltage DC circuits where increased performance is not required from them.
Where fuses cannot effectively solve the problem of protecting electronic equipment and devices from current overloads, they can be successfully used in circuits for protecting electronic devices from overvoltage.
The principle of operation of this protection is simple: when the supply voltage level is exceeded, a threshold device is triggered, causing a short circuit in the load circuit, as a result of which the fuse conductor melts and breaks the load circuit.
The method of protecting equipment from overvoltage by forcibly blowing the fuse is, of course, not ideal, but has become quite widespread due to its simplicity and reliability. When using this method and choosing the optimal protection option, it is worth considering how fast the circuit breaker should be, whether it is worth blowing the fuse during short-term voltage surges or introducing a delay element. It is also advisable to include in the circuit an indication of the fact that the fuse has blown.
The simplest protective device that allows you to save the protected electronic circuit is shown in Fig. 4.1. When the zener diode breaks down, the thyristor turns on and shunts the load, after which the fuse blows. The thyristor must be designed for a significant, albeit short-term current. The use of surrogate fuses in the circuit is completely unacceptable, since otherwise both the protected circuit, the power source, and the protective device itself may simultaneously fail.

Rice. 4.1. The simplest surge protection

Rice. 4.2. Noise-proof load protection circuit against overvoltage

An improved load protection circuit from overvoltage, supplemented by a resistor and capacitor, is shown in Fig. 4.2. The resistor limits the maximum current through the zener diode and the control junction of the thyristor, the capacitor reduces the likelihood of protection tripping during short-term surges in the supply voltage.
The following device (Fig. 4.3) will protect radio equipment from failure due to accidental polarity reversal or excess
supply voltage, which often happens when the generator in a car malfunctions.
With the correct polarity and rated supply voltage, diode VD1 and thyristor VS1 are closed, and current flows through fuse FU1 to the output of the device.

Rice. 4.3. Radio equipment protection circuit with fault indication

If the polarity is reversed, then diode VD1 opens and fuse FU1 burns. Lamp EL1 lights up, signaling an emergency connection.
With the correct polarity, but the input voltage exceeding the set level set by the zener diodes VD2 and VD3 (in this case - 16 B), the thyristor VS1 opens and short-circuits the circuit, which causes the fuse to blow and the emergency lamp EL1 to light.
Fuse FU1 must be designed for the maximum current consumed by the radio equipment.
GTL logic elements are usually operational in a narrow range of supply voltages (4.5...5.5 V). If an emergency decrease in the supply voltage is not so dangerous for the “health” of the microcircuits, then increasing this voltage is completely unacceptable, since it can lead to damage to all the microcircuits of the device.
In Fig. 4.4 shows a simple and quite effective scheme for protecting 7777 devices from overvoltage, published in the Bulgarian magazine. The protection method is extremely simple: as soon as the supply voltage exceeds the recommended level by only 5% (i.e. reaches a value of 5.25 B), the threshold device will operate and the thyristor will turn on. A short circuit current begins to flow through it, which blows out fuse FU1. Of course, surrogate fuses cannot be used as a fuse, since in this case the power supply protecting the thyristor circuit, and then the protected microcircuits, may fail.
The disadvantage of the device is the lack of indication of a blown fuse. It is easy to introduce this function into the device yourself. Examples of organizing the indication of a break in the supply circuit are also given in Chapter 36 of the book.

Rice. 4.4. Surge protection circuit for TTL chips

Rice. 4.5. Scheme of AC and DC surge protection device

Diagram of a device that, in the event of a power failure, will protect a TV, VCR, refrigerator, etc. from overvoltage, shown in Fig. 4.5.
The protection response voltage is determined by the voltage drop across the composite zener diode VD5+VD6 and is 270 B.
Capacitors C1 and C2, together with resistor R1, form an RC circuit, which prevents the device from triggering during pulse surges in the network.
The scheme works as follows. When the network voltage is up to 270 V, the zener diodes VD3, VD4 are closed. Thyristors VS1, VS2 are also closed. When the operating voltage is more than 270 V, the zener diodes VD3, VD4 open, and the opening voltage is supplied to the control electrodes of the thyristors VS1, VS2. Depending on the polarity of the half-cycle of the mains voltage, the current passes either through the thyristor VS1 or through VS2. When the current exceeds 10 A, circuit breakers (plugs, fuses) trip, disconnecting electrical appliances from the power supply. The load (not shown in the figure) is connected in parallel with the thyristors. You can check the functionality of the device using LATR.
The device is also operational on direct current.

Rice. 4.6. Self-locking surge protection relay circuit diagram

The overvoltage protection device (Fig. 4.6) differs favorably from the previous ones in that it does not cause irreversible damage to the protection element. Instead, at a voltage above 14.1 V, the chain of zener diodes VD1 - VD3 breaks through, the thyristor VS1 turns on and self-blocks, relay K1 is activated and disconnects the load circuit with its contacts.
The protection device can be restored to its original state only after operator intervention - to do this, press the SB1 button. The device also goes into standby mode after a short power outage. The disadvantages of this protection device include its high sensitivity to short-term overvoltages.
Device (patent DL-WR 82992), the circuit diagram of which is shown in Fig. 4.7, can be used to protect the load from unacceptably high output voltage. Under normal conditions, transistor VT1 operates in a mode where the voltage between its collector and emitter is small, and little power is dissipated across the transistor (the base current is determined by resistor R1). The resistance of the zener diode VD2 in this case is large and the thyristor VS1 is closed.

Rice. 4.7. Semiconductor load overvoltage protection relay circuit

When the voltage at the output of the device increases above a certain value, a current begins to flow through the zener diode, which leads to the opening of the thyristor. At the same time, transistor VT1 closes, and the voltage at the output of the device becomes close to zero. The protection can only be disabled by disconnecting the power source.
The described device must be included in the output circuit of the stabilizers so that the feedback signal is supplied from a circuit located behind the protection system. With a rated output voltage of 12 V and a current of 1 A, the device can use the KT802A transistor, the KU201A - KU201K thyristor, and the D814B zener diode. The resistance of resistor R1 should be 39 Ohms (power dissipation in the absence of an automatic system that disconnects the stabilizer from the network is 10 W), R2 - 200 Ohms, R3 - 1 kOhm.

The amount of electricity consumed by the population increases every year. A modern person cannot do without a washing machine, microwave oven, TV, refrigerator, air conditioner and other equipment. Unfortunately, the old apartment wiring was not designed for such a large number of consumers. And for uninterrupted and long-term operation of household appliances, a stable power supply is necessary. Therefore, first of all, you need to check the condition of the electrical wiring and make a partial or complete replacement. Electrical installation must be carried out competently, carefully and with high-quality materials.

The cause of failure of household appliances can be either high or low voltage in the network. Sudden changes in electricity can also render the equipment unusable.

There are several ways to protect against overvoltage. A high surge of energy can be triggered by lightning discharges. The easiest way to protect against lightning strikes is to turn off all equipment from the network. However, it is not always possible to be at home. Therefore, to protect against overvoltage, a surge arrester must be installed in the cabinet with the electric meter and circuit breakers. With three-phase power supply, a surge arrester is installed on each phase, that is, three arresters are needed.

A cheap and ineffective means of protection includes the usual one. You should not buy the cheapest filter, because it will be an ordinary extension cord. As a rule, the network is equipped with an interference filter, a fuse and a protective element -. When the voltage rises above 260, the varistor sharply changes its resistance and the fuse blows, turning off the connected equipment. A surge protector will not provide 100% protection.

Voltage drops can be caused by the deplorable condition of transformer substations and electrical wiring in houses and entrances. It is also impossible to exclude the human factor when, as a result of illiterate work by an electrician, equipment in the entire house burns out.

To protect against overvoltage, you can use voltage stabilizers and uninterruptible power supplies (UPS). There are advantages and disadvantages here. For a good stabilizer or high-power UPS you need to pay a round sum of money. But for powering expensive equipment, such protection is an ideal option.

To save money and protect your household appliances from power surges, it is recommended to install an AZM-40A voltage protection unit. If the voltage changes above 265 volts or drops below 170 volts, the unit turns off all connected equipment. When the voltage level is restored, the protection unit will connect the equipment automatically after 2 minutes.

Another most affordable method of dealing with overvoltage is to install an RCD together with DPN-260 (overvoltage sensor). When the voltage increases, the DPS commands the RCD to disconnect consumers. To supply electricity, you just need to turn on the RCD.

To have maximum protection, use all protection methods. Install arresters, a voltage protection unit, a voltage stabilizer, a UPS and conventional surge protectors. After this, your equipment will be under reliable protection and you can sleep peacefully.

Lightning is a powerful electrical discharge (Fig. 5.32), formed when clouds or ground are highly electrified. Lightning discharges can occur within a cloud, between adjacent electrified clouds, or between an electrified cloud and the ground. The electric field of the cloud has a huge intensity - millions of V/m. When large, oppositely charged regions come close enough to each other, some electrons and ions run between them, creating a glowing ionized channel through which other charged particles rush after them. As the ionized channel (leader) moves toward the ground, the field strength at its end increases, and under its action, a response streamer is ejected from objects protruding on the surface of the earth, connecting to the leader. This is how a lightning discharge occurs. This feature of lightning is used to create a lightning rod.

All production facilities must be equipped with a lightning protection system. Lightning protection of industrial buildings is an essential safety element that can prevent serious material damage and loss of life.

The primary action of lightning is a direct blow is dangerous due to thermal and mechanical destruction of the building. When lightning directly hits the wires, an overvoltage occurs in the line, causing destruction of the insulation of electrical equipment, and high currents cause thermal damage to the conductors.

Secondary action of lightning characterized by the formation of electric currents in closed conductive systems of a building (electrical wiring, pipelines, etc.). The process of transferring electrical potentials generated by a lightning strike through external metal structures (pipelines) into the protected building can lead to a fire, explosion, and failure of electrical and electronic equipment (Table 5.11).

Possible consequences of lightning

Manifestations dangers	Damaging factors	Consequences
Direct lightning strike to a building	Discharge up to 200 kA, voltage 1000 kV, temperature 30,000°C	Damage to people, destruction of parts of the building, fires
Remote discharge during a lightning strike in communications (up to 5 km or more)	Introduced lightning potential through power supply wires and metal pipelines (possible overvoltage impulse - hundreds of kV)	Human injuries, violation of electrical wiring insulation, equipment failure, loss of databases, failures in computer systems
Close (up to 500 m from the building) lightning discharge	Induced lightning potential in conductive parts of a building and electrical installations (possible overvoltage impulse - tens of kV)	Human injury, violation of electrical wiring insulation, fires, equipment failure, loss of databases, failures in computer systems
Switching and short circuits in the low voltage circuit	Overvoltage impulse (up to 4 kV)	Equipment failure, database loss, computer system failures

Another dangerous manifestation of lightning is shock wave. A lightning discharge is an electrical explosion and in some aspects is similar to the detonation of an explosive. It causes a shock wave that is dangerous in the immediate vicinity.

For example, with a current rise rate of 30,000 amperes per 0.1 millisecond and an ionized channel diameter of 10 cm, the following shock wave pressures can be observed:

• - at a distance from the center of 5 cm (border of the luminous lightning channel) - 0.93 MPa (structural destruction, severe human concussions);
• - at a distance of 0.5 m - 0.025 MPa (destruction of fragile building structures and human injury);
• - at a distance of 5m - 0.002 MPa (breaking glass and temporarily stunning a person).

The dangerous effect of lightning on a person can manifest itself in the following: contact damage (from induced potentials on metal parts of equipment), ophthalmological damage (lightning flash), step voltage (when lightning current spreads in the ground), blunt injury (due to the action of a shock wave), direct strike (direct lightning strike on a person).

When designing a lightning protection system, the purpose of the facility, the features of its design and the geographic location of the region, which is directly related to the intensity of thunderstorm activity, are taken into account.

Lightning protection of industrial buildings is developed based on the type of hazardous impact that occurs during an electric lightning discharge. All industrial facilities require individually selected measures to protect against the effects of atmospheric surges. High-rise objects are most at risk, therefore, first of all, high-rise buildings, masts, pipes, and power line supports need protection.

The primary source of damage is lightning current. Depending on the point of injury, the following sources of damage are distinguished (Table 5.12):

• - S- lightning strike to a building (structure);
• - S2- lightning strike near a building (structure);
• - S3- lightning strike in communication lines;
• - S4- lightning strike near communication lines.

Depending on the characteristics of the building (structure) being protected, a lightning strike can cause various damages. In practice, when assessing risk, there are three main types of damage that can occur as a result of a lightning strike:

• - D- harm to living beings;
• - D1- physical damage to the building (structure) and (or) communication lines;
• - D3- failure of electrical and electronic systems.

Damage to a building (structure) due to lightning may be limited to part of the structure or may extend to several structures. Damage may affect areas adjacent to the structure or the environment (for example, chemical or radioactive contamination of the area).

Each type of damage, alone or in combination with others, can lead to various direct and indirect losses in the protected structure. The type of losses that occur depends on the characteristics of the structure and its parts. The following types of losses should be considered:

• - L- associated with death and injury of people;
• - L2- with complete or partial destruction of public communications;
• - L3- causing damage to cultural objects;
• - L4 - economic (related to the destruction of a building (structure), its part and (or) disruption or cessation of activity).

Established combinations of possible damage and losses depending on the type of source)