Type of surge protection device. Uzip installation - connection diagrams, installation rules. What dangers do overvoltage pose? Examples
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It has become the norm for all of us that in the distribution panels of residential buildings, it is mandatory to install incoming circuit breakers, modular circuit breakers for outgoing circuits, RCDs or differential circuit breakers in rooms and equipment where possible current leaks are critical (bathrooms, hob, washing machine, boiler ).
In addition to these mandatory switching devices, almost no one needs to explain why a voltage control relay is needed.
SPD or voltage relay
Everyone started installing them everywhere. Roughly speaking, it protects you from 380V instead of 220V going into the house. At the same time, you don’t need to think that increased voltage gets into the wiring due to an unscrupulous electrician.
Natural phenomena that do not depend on the qualifications of electricians are quite possible. A tree simply fell and broke the neutral wire. 
Also, do not forget that any overhead line becomes obsolete. And even the fact that a new line has been connected to your house using a self-supporting insulated insulation system, and everything in your house is installed according to the rules, does not guarantee that everything is fine at the supply transformer substation itself - the transformer substation. 
There, the zero on the busbar may also oxidize or the contact on the transformer pin may burn out. No one is immune from this.
That is why all new electrical panels are no longer assembled without UZM or RN of various modifications. 
As for surge voltage protection devices, or SPDs for short, most here have doubts about the need to purchase them. Are they really that necessary, and is it possible to do without them?
Such devices appeared quite a long time ago, but still no one is in a hurry to install them en masse. Few ordinary consumers understand why they are needed at all. 
The first question that arises in their minds is: “I installed a voltage surge relay, why do I need another SPD?”
No voltage relay will save you from this, but will most likely burn out along with all other equipment. At the same time, the SPD does not protect against small differences of tens of volts or even hundreds. 
For example, devices for installation in home panels, assembled on varistors, can only operate when the variable reaches values above 430 volts.
Therefore, both LV and SPD devices complement each other.
Protecting your home from thunderstorms
A thunderstorm is a spontaneous phenomenon and it is still not very easy to calculate it. In this case, lightning does not have to hit the power line directly. It is enough to hit next to her. 
Even such a lightning discharge causes an increase in the voltage in the network to several kilovolts. In addition to equipment failure, this is also fraught with the development of a fire.
Even when lightning strikes relatively far from overhead lines, pulse surges occur in the networks, which damage the electronic components of home appliances. A modern electronic meter with its filling may also suffer from this impulse. 
The total length of wires and cables in a private house or cottage reaches several kilometers.
This includes both power circuits and low current:
- security alarm
All these wires take on the consequences of a lightning strike. That is, all your kilometers of wiring receive a gigantic interference, from which no voltage relay can save you.
The only thing that will help and protect all the equipment, costing several hundred thousand, is a small box called an SPD. 
They are installed mainly in cottages, and not in high-rise apartments, where the supply to the house is made with an underground cable. However, do not forget that if your transformer substation is not powered by a 6-10 kV cable line, but by an overhead overhead line or overhead line (SIP-3), then the effect of a thunderstorm on medium voltage can also be reflected on the 0.4 kV side. 
Therefore, do not be surprised when, during a thunderstorm in your high-rise building, many neighbors’ WiFi routers, cordless phones, televisions and other electronic equipment simultaneously fail.
Lightning can strike a power line several kilometers from your home, but the impulse will still arrive at your outlet. Therefore, despite their cost, all electricity consumers should think about purchasing an SPD. 
The price of high-quality models from Schneider Electric or ABB is approximately 2-5% of the total cost of rough electrics and an average switchboard. In total, this is not such a huge amount of money.
SPD classes
Today, all surge voltage devices are divided into three classes. And each of them plays its role. 
The first class module dampens the main impulse; it is installed on the main input panel.
After the largest overvoltage has been extinguished, the residual impulse is taken over by a class 2 SPD. It is mounted in the distribution panel of the house. 
If you do not have a Class I device, there is a high probability that the entire impact will be taken by the II module. And this could end very sadly for him.
Therefore, some electricians even discourage customers from installing impulse protection. Motivating this is that since you cannot provide the first level, then you should not spend money on it at all. There will be no point.
However, let's see what not a familiar electrician says about this, but the leading company for lightning protection systems, Citel: 
That is, the text directly states that class II is mounted either after class 1 or AS A STANDALONE DEVICE.
The third module directly protects a specific consumer.
If you do not want to build all this three-stage protection, purchase SPDs that are initially designed to work in three zones 1+2+3 or 2+3. 
Such models are also produced. And they will be the most universal solution for use in private homes. However, their cost will certainly scare off many.
Electrical panel diagram with SPD
The circuit diagram of a distribution board that is well-equipped from the point of view of protection against all voltage surges and surges should look something like this.
At the input in front of the meter there is an input circuit breaker that protects the metering device and the circuits inside the panel itself. Next is the counter. 
Between the meter and the input machine there is an SPD with its own protection. The electricity supply organization can, of course, prohibit such installation. But you can justify this by the need for surge protection for the meter itself.
In this case, it will be necessary to mount the entire circuit with the devices in a separate box under a seal in order to prevent free access to exposed live parts up to the meter. 
However, here the issue of replacing the triggered module and breaking the seals will arise. Therefore, agree on all these points in advance.
After the metering device there are:
- voltage relay UZM-51 or equivalent
- simple modular machines
If there are no questions with the usual components when assembling such a shield, then what should you pay attention to when choosing an SPD?
For operating temperature. Most electronic types are designed to operate at ambient temperatures down to -25C. Therefore, it is not recommended to install them in street shields.
The second important point is the connection diagrams. Manufacturers may produce different models to suit different grounding systems. 
For example, it will no longer be possible to use the same SPDs for TN-C or TT and TN-S systems. You will not achieve correct operation from such devices.
Connection diagrams
Here are the basic SPD connection diagrams depending on the design of the grounding systems using the example of models from Schneider Electric. Connection diagram for a single-phase SPD in a TT or TN-S system: 
The most important thing here is not to confuse the connection location of the N-PE insert cartridge. If you plug it into a phase, you will create a short circuit.
Diagram of a three-phase SPD in a TT or TN-S system: 
Connection diagram for a 3-phase device in the TN-C system: 
What should you pay attention to? In addition to the correct connection of the neutral and phase conductors, the length of these same wires plays an important role.
From the connection point in the device terminal to the grounding busbar, the total length of the conductors should be no more than 50cm! 
And here are similar diagrams for surge protectors from ABB OVR. Single-phase option: 
Three-phase circuit: 
Let's go through some of the schemes separately. In the TN-C circuit, where we have combined protective and neutral conductors, the most common protection solution is to install an SPD between the phase and the ground.
Each phase is connected through an independent device and operates independently of the others. 
In the TN-S network version, where the neutral and protective conductors have already been separated, the circuit is similar, but here an additional module is mounted between zero and ground. In fact, the entire brunt of the blow falls on him. 
That is why, when selecting and connecting the N-PE SPD option, individual characteristics for the pulse current are indicated. And they are usually greater than the phase values.
In addition, do not forget that thunderstorm protection is not only a properly selected surge protector. This is a whole complex of events.
They can be used both with and without lightning protection on the roof of the house. 
Particular attention should be paid to a high-quality grounding loop. 
One corner or pin driven into the ground to a depth of 2 meters will clearly not be enough here. A good ground resistance should be 4 ohms.
Operating principle
The operating principle of the SPD is based on attenuating the voltage surge to a value that the devices connected to the network can withstand. In other words, this device, even at the entrance to the house, dumps excess voltage onto the ground loop, thereby saving expensive equipment from a destructive impulse.
Determining the status of the protection device is quite simple:
- green indicator – module working
However, do not enable the module with the red flag. If there is no spare one, then it is better to dismantle it altogether.
An SPD is not always a disposable device, as some people think. In some cases, class 2 and 3 models can fire up to 20 times!
Circuit breakers or fuses in front of the SPD
To maintain uninterrupted power supply in the house, it is also necessary to install a circuit breaker that will turn off the surge protector. The installation of this machine is also due to the fact that at the moment the pulse is removed, a so-called accompanying current arises.
It does not always allow the varistor module to return to the closed position. In fact, it does not recover after being triggered, as in theory it should.
As a result, the arc inside the device is maintained and leads to a short circuit and destruction. Including the device itself. 
In the event of such a breakdown, the machine is triggered and de-energizes the protective module. Uninterrupted power supply to the house continues.
Remember that this machine does not primarily protect the arrester, but your network.
At the same time, many experts recommend installing not even a machine, but modular fuses as such protection. 
This is explained by the fact that the machine itself during a breakdown is exposed to a pulsed current. And its electromagnetic releases will also be under increased voltage.
This can lead to breakdown of the trip coil, burning of contacts and even failure of the entire protection. In fact, you will find yourself unarmed in the face of a short circuit.
Therefore, installing an SPD after a machine is much worse than after fuses.
There are, of course, special automatic switches without inductors, which have only thermal releases in their design. For example Tmax XT or Formula A. 
However, considering this option for cottages is not entirely rational. It is much easier to find and buy modular fuses. In this case, you can choose the GG type.
They are capable of protecting over the entire range of overcurrents relative to the rated ones. That is, if the current has increased slightly, GG will still turn it off at a given time interval.
There is, of course, a minus to the circuit with a machine or PC directly in front of the SPD. We all know that thunderstorms and lightning are long-term, not one-time phenomena. And all subsequent impacts may be unsafe for your home. 
The protection had already worked the first time and the machine gun was knocked out. And you won’t even guess about it, because your power supply was not interrupted.
Therefore, some people prefer to install an SPD immediately after the input circuit breaker. So that when triggered, the voltage in the entire house is turned off. 
However, there are pitfalls and rules here too. The protective circuit breaker cannot be of any rating, but is selected according to the brand of the SPD used. Here is a table of recommendations for choosing circuit breakers mounted in front of surge protection devices: 
If you think that the lower the nominal value of the machine is installed, the more reliable the protection will be, you are mistaken. The pulse current and voltage surge can be of such magnitude that they will lead to the circuit breaker tripping even before the SPD operates.
And accordingly, you will again be left without protection. Therefore, choose all protective equipment wisely and according to the rules. SPD is a quiet, but very timely protection against dangerous electricity, which comes into operation instantly.
Connection errors
1 The most common mistake is installing an SPD in an electrical room with a poor grounding circuit.There will be no sense in such protection. And the very first “successful” lightning strike will burn both all your devices and the protection itself. 
Check the technical documentation of the surge protector and consult with an experienced electrician responsible for electrical equipment, who should be aware of what grounding system is used in your home. 
Surge protection is a blocking device against excessive voltage in the form of current pulses. It is installed in apartments and houses and has such advantages as high efficiency, low cost, and perfect design.
This type of equipment protection for power distribution lines up to 1000 volts serves to protect against elevated voltages associated with surges.
Sources of impulses can be:
- Lightning discharges into the power supply circuit or into the lightning rod of an object near the power input to the object.
- Lightning discharges at a distance of up to several thousand meters near the facility's communications.
- Connections of sufficiently powerful loads, short circuits in power distribution lines.
- Interference from electromagnetic waves, from electronic devices and equipment.
Offices and apartments have a lot of household appliances, computers and other expensive equipment that consume electricity. Therefore, in order to avoid the risk of damage and failure from equipment surges, it is better to purchase and install a protective device.
One sudden voltage drop is enough to cause several household devices to fail at once. This issue is especially relevant in country houses and country houses, in which the power supply, heating, and water supply systems are connected to autonomous power networks. Electrical safety requirements must not be neglected.
Surge protection serves to limit voltage in the form of pulses from lightning strikes, connections of a powerful inductive load (This can be large electric motors, a transformer), etc.
Types and classes of protection against voltage surges
- Type 1. Class B . The devices are used in case of a possible direct lightning strike into the power circuit or near an object into the ground. If the power supply is carried out via an overhead line, and also if there is a lightning rod, then the installation of pulse protection is strictly necessary. The equipment is mounted in an iron casing, next to the power input to the building, or in a distribution board.
- Type 2. Class C. It has reduced protection against voltage surges and is mounted at the entrance to the electrical installation and into the room as the 2nd level of protection. Mounted in distribution panels.
- Type 3. ClassD. Protects electrical equipment from residual overvoltage, unbalanced currents, and high-frequency interference. Mounted near electrical appliances. It is recommended to install impulse protection near the consumer, no more than five meters from it, and if there is a lightning rod, then directly at the consumer’s power input, since the current in the lightning rod provokes a significant impulse in the electrical wiring.
Operating principle
The operation of surge protection can be easily explained since it has a simple surge voltage output circuit. A shunt is built into the device circuit, through which current is supplied to the load of the consumer connected to the power supply. A jumper is connected from the shunt to the ground, which consists of a spark gap or a varistor.
At normal network voltage, the varistor has a resistance of several mOhms. When an overvoltage appears on the line, the varistor begins to pass current through itself, which then flows into the ground. This is how impulse protection works simply. When the supply voltage normalizes, the varistor ceases to be a current conductor, and power is supplied to the consumer via the built-in shunt.
Protection device
Surge protection is based on varistors or arresters. There are also indication devices that give signals about failure of the protection. The disadvantages of varistor protection include the fact that when the protection is triggered, the varistors heat up, and it takes time to cool down to operate again. This adversely affects operation in stormy weather and multiple lightning strikes.
Often, protection on varistors is made with a device for mounting on. The varistor is easily changed by simply removing it from the protection housing and installing a new varistor.
Practical use
To reliably protect an energy consumer from overvoltage, you must first install a good one. For this purpose, circuits with a protective and separated neutral conductor are used.
Next, protective devices are installed in such a way that the distance from adjacent protective devices is at least 10 meters along the power line wire. This rule is important for the correct order of protection activation.
If an overhead line is used for power supply, then the optimal application would be pulse protection based on fuses and arresters. In the main panel of the house, protection is installed on class 1 and 2 varistors, in floor panels - class 3. To further protect electrical consumers, portable impulse protection in the form of extension cords with fuses is plugged into sockets.
Such protective measures reduce the likelihood of exposure to increased voltage, but do not provide a complete guarantee. Therefore, during thunderstorms, it is best to turn off sensitive devices and equipment if possible.
How to protect the protection device itself
The protection device itself also needs to be protected from damage. They can arise due to the destruction of parts when absorbing overvoltage pulses. There have been cases where the protection devices themselves caught fire and caused a fire.
- Class 1 devices are protected by 160 amp inserts.
- Class 2 is protected by 125 amp inserts.
If the fuse rating is higher than recommended, then you need to install an auxiliary insert that protects the panel parts from malfunctions. When high voltage is applied to the protection for a long time, the varistors become very hot. The thermal release turns off power protection if the varistor reaches a critical temperature.
Surge protection can be equipped. Class 1 protection can only be protected by inserts, since the inserts interrupt short circuit currents at high voltages.
It can be concluded that the correct use of surge protection makes it possible to effectively protect equipment from malfunctions caused by excessive power line voltage.
Impulse protection -how to choose
by lightning current
Electricity can be supplied to a building through an overhead line with the following properties:
- Insulated wires, self-supporting.
- Simple wires without insulation.
If the wires of the overhead line and its elements are insulated, this affects the effective protection and connection circuits, and also reduces the effect of a lightning strike.
SPD in the TN-C-S system When connecting a house from an isolated line, grounding is carried out according to the diagram shown in the figure. Surge protection is installed between phases and PEN. The point of disconnection of PEN to PE and N conductors at a distance of 30 m from the house requires auxiliary protection.
If the house has installed lightning protection, there are metal communications, then this affects the circuit and choice of connection of impulse protection, and also negatively affects the electrical safety of the house.
Options for proposed schemes
Option 1. Conditions.
Electricity is supplied through an insulated overhead line.
- No lightning protection.
- There are no metal structures outside the house. The grounding circuit is made according to the TN – C – S scheme.
Solution
In this case, it is unlikely that there will be a direct lightning strike to the house, due to:
- Availability of insulation of overhead line wires.
- Lack of lightning rod and external metal communications on the house.
As a result, protection against high voltage pulses, which have a shape of 8/20 μs for current, will be sufficient. Suitable for impulse protection with a mixed protection class in one housing.
The current range from voltage pulses is selected from the range from 5 to 20 kiloamperes. It is better to choose the largest value.
Option 2. Conditions.
The electric current flows through an insulated overhead line.
- There is no lightning protection.
- Outside the house there are metal communications for gas or water supply. The grounding system is made according to the TN-C-S scheme.
Solution
If we compare it with the previous option, here there can be a lightning strike on a pipe with a current of up to 100 kiloamperes. Inside the pipe, this current will be divided into two ends of 50 kiloamperes. On our side of the building, this part will be divided by 25 kiloamperes into the building and grounding.
The PEN wire will take over a portion of 12.5 kiloamperes, and the rest of the pulse of the same magnitude will pass through the protection device into the phase conductor. The same protection device can be used as before.
Option 3. Conditions.
Electricity is supplied through an overhead line without insulation.
Solution
There is a high probability of lightning discharge into the wires; the building uses a CT grounding scheme.
SPD in the TT system Pulse protection must be provided both from the phase wires relative to the ground and from the neutral wire. Protection from the neutral wire to ground is rarely used due to local conditions.
When installing wires to an open line without insulation, the safety of the home is influenced by the shape of the branch, which can be made:
- By cable.
- Wires with insulation, like an insulated overhead line.
- Exposed wires.
When branching over the air, less risks are created by insulated wires with a cross-section of at least 16 mm square. The likelihood of a lightning strike on such wires is very low. A lightning discharge is possible into the wire cutting unit near the insulators at the input. In this case, half the voltage from the lightning discharge will appear on the phase.
Modern man, trying to keep up with the times, fills his home with electrical appliances for a wide variety of purposes. But not every homeowner thinks that if even a very short-term pulse voltage appears in the network, several times higher than the nominal voltage, his entire expensive fleet of electrical equipment and electronics may fail. What is noteworthy is that the impact of overvoltage on electrical consumers is detrimental in that the affected equipment, as a rule, becomes unsuitable for repair. This force majeure event, although not frequent, can be guaranteed to be a consequence of overvoltage in networks caused by thunderstorms, emergency phase overlap or switching processes. The so-called surge protection devices are designed to protect electrical equipment. We discussed the operating principle of SPDs, classes and the difference between them below.
SPD classification
Surge voltage protection devices are a broad and general concept. This category of devices includes devices that can be divided into classes:
- I class. Designed to protect against direct exposure to lightning. These devices must be equipped with input distribution devices (IDUs) of administrative and industrial buildings and residential apartment buildings.
- II class. They provide protection of electrical distribution networks from overvoltages caused by switching processes, as well as performing the functions of the second stage of protection against lightning strikes. Mounted and connected to the network in distribution boards.
- III class. They are used to protect equipment from surges caused by residual voltage surges and asymmetrical voltage distribution between the phase and the neutral wire. Devices of this class also operate in high-frequency interference filter mode. They are most relevant for the conditions of a private house or apartment; they are connected and installed directly at consumers’ premises. Particularly popular are devices that are manufactured as modules equipped with a quick-release mount for installation on, or have the configuration of electrical sockets or network plugs.
Device types
All devices that provide protection against surge voltages are divided into two types, which differ in design and principle of operation. Let's look at how different types of SPDs work.
Valve and spark gaps. The principle of operation of the arresters is based on the use of the spark gap effect. The design of the arresters provides an air gap in the jumper connecting the phases of the power line with the grounding loop. At the nominal voltage value, the circuit in the jumper is broken. In the event of a lightning discharge, the result is a breakdown of the air gap in the power line, the circuit between the phase and the ground is closed, and the high voltage pulse goes directly to the ground. The design of the valve gap in a circuit with a spark gap includes a resistor on which the high-voltage pulse is damped. In most cases, arresters are used in high voltage networks.
Surge suppressors (SPDs). These devices replaced outdated and bulky arresters. In order to understand how the limiter works, you need to remember the properties of nonlinear resistors, which are built on the use of their current-voltage characteristics. A varistor is used as nonlinear resistors in an SPD. For people not experienced in the intricacies of electrical engineering, a little information about what it consists of and how it works. The main material for the manufacture of varistors is zinc oxide. In a mixture with oxides of other metals, an assembly consisting of p-n junctions is created, which has current-voltage characteristics. When the voltage in the network corresponds to the nominal parameters, the current in the varistor circuit is close to zero. When an overvoltage occurs, a sharp increase in current occurs at the p-n junctions, which leads to a decrease in voltage to the nominal value. After normalizing the network parameters, the varistor returns to non-conducting mode and does not affect the operation of the device.
The compact dimensions of surge arresters and the wide range of varieties of these devices have made it possible to significantly expand the scope of application of these devices; it has become possible to use surge protectors as a means of surge protection for a private house or apartment. However, pulse voltage limiters assembled on varistors, despite all their advantages over arresters, have one significant drawback - limited service life. Due to the thermal protection built into them, the device remains inoperative for some time after activation; for this reason, a quick-release device is provided on the SPD body, allowing quick replacement of the module.
You can learn more about what an SPD is and what its purpose is from the video:
How to arrange protection?
Before proceeding with the installation and connection of surge protection devices, it is necessary, otherwise all work on arranging the SPD will lose all meaning. The classic scheme provides 3 levels of protection. Arresters (surge protection class I) are installed at the input, providing lightning protection. The next class II protective device, usually an arrester, is connected in the distribution board of the house. The degree of its protection should ensure a reduction in the magnitude of the overvoltage to parameters that are safe for household appliances and the lighting network. In the immediate vicinity of electronic products sensitive to current and voltage fluctuations, class III is desirable.
When connecting SPDs, it is necessary to provide for their current protection and protection against short circuits by an input circuit breaker or fuses. We will tell you more about the installation of these protective devices in a separate article.
So we looked at the operating principle of SPDs, classes and the difference between them. We hope the information provided was useful to you!
Many processes that occur in our home, we do not even assume that this happened due to overvoltage. Our Philips TV burned out, and we blame the manufacturer for buying a Samsung. We don’t even think about why it burned out.
What is surge voltage?
Overvoltage is a short-term increase in voltage at a power supply point above the permissible value. After this jump, the network voltage is restored to its original value. The degree of voltage distortion is characterized by the pulse voltage indicator.
For example, our apartment receives a sinusoidal voltage of 220 V. Pulse overvoltages can occur in the electrical network (we will look at the reason for their occurrence a little later), this is when an overvoltage surge occurs, lasting several milliseconds but the amplitude (maximum value) can reach up to 10 thousand. IN.
Why is surge voltage dangerous for household electrical appliances?
The insulation of any electrical appliance is designed for a certain voltage level. As a rule, electrical appliances with a voltage of 220 - 380 V are designed for an overvoltage pulse of about 1000 V. What if overvoltages with a pulse of 3000 V occur in the network? In this case, insulation breakdown occurs. A spark appears - an ionized gap of air through which an electric current flows. This results in an electric arc, short circuit and fire.
Please note that insulation damage can occur even if all your appliances are unplugged. Electrical wiring, distribution boxes, and sockets will still remain energized in the house. These network elements are also not protected from surge voltage.
Causes of surge voltage
One of the causes of surge surges is lightning discharges (lightning strike). Switching overvoltages that arise as a result of switching on/off consumers with a large load. In case of phase imbalance as a result of a short circuit in the network.
Protecting your home from surge voltages
It is impossible to get rid of pulse overvoltages, but in order to prevent insulation breakdown, there are devices that reduce the magnitude of pulse overvoltages to a safe value.
Such protection devices are SPD - surge protection device.
Exists partial And full protection by SPD devices.
Surge suppressor is one of the most widely known high-voltage devices used to protect the network.
Description of the device
To begin with, it is worth explaining why, in principle, pulse overvoltages occur and why they are dangerous. The reason for the appearance of this process is a disturbance in the atmospheric or switching process. Such defects are quite capable of causing enormous damage to electrical equipment that is exposed to such influence.
Here it is worth giving an example of a lightning rod. This device does an excellent job of diverting a strong discharge striking an object, but it will not be able to help in any way if the discharge enters the network through overhead lines. If this happens, then the very first conductor that gets in the way of such a discharge will fail, and can also cause a breakdown of other electrical equipment that is connected to the same electrical network. Elementary protection is to turn off all devices during a thunderstorm, but in some cases this is impossible, and therefore devices such as surge arresters were invented.
What will using the device give?
If we talk about conventional means of protection, then their design is somewhat worse than that of surge arresters. In the usual version, carborundum resistors are installed. An additional design is the spark gaps, which are connected to each other in a series manner.
Surge suppressors also contain elements such as nonlinear transistors. The basis for these elements was zinc oxide. There are several such parts, and they are all combined into one column, which is placed in a special case made of a material such as porcelain or polymer. This ensures completely safe use of such devices, and also reliably protects them from any external influences.
It is important to note here that the main feature of the surge suppressor is the design of zinc oxide resistors. This design allows you to greatly expand the functions that the device can perform.
Technical specifications
Like any other device, an arrester has a basic characteristic that determines its performance and quality. In this case, this indicator was the amount of operating voltage that can be supplied to the terminals of the device without any time limitation.
There is one more characteristic - conduction current. This is the value of the current that passes through the device under the influence of voltage. This indicator can only be measured under conditions of actual use of the device. The main numerical indicators of this parameter are capacity and activity. The total value of this characteristic can reach several hundred microamps. Based on the obtained value of this characteristic, the performance of the surge suppressor is assessed.
Description of the arrester device
To make this device, manufacturers use the same electrical engineering and design techniques that are used to make other products. This is most noticeable when examining the dimensions and materials used to make the case. The appearance also has some similarities with other devices. However, it is worth noting that special attention is paid to such things as the installation of a surge suppressor, as well as its further connection to general consumer-type electrical installations.
There are several requirements that apply specifically to this class of devices. The surge arrester housing must be completely protected from direct human contact. The risk of the device catching fire due to possible overloads must be completely eliminated. If the element fails, this should not result in a short circuit in the line.
Purpose and use of surge arresters
The main purpose of nonlinear surge suppressors is to isolate electrical equipment from atmospheric or switching overvoltages. This device belongs to the group of high-voltage devices.
These devices do not have such a section as the spark gap. If we compare the operating range of an arrester and a conventional one, the limiter is able to withstand deeper voltage drops. The main task of this device is to withstand these loads without time limits. Another significant difference between a surge suppressor and a conventional valve one is that the dimensions, as well as the physical weight of the structure in this case are much lower. The presence of such an element as a lid made of porcelain or polymers has led to the fact that the inside of the device is reliably protected from external environmental influences.
OPN-10
The design of this device is somewhat different from a conventional surge arrester. In this embodiment, a column of varistors is used, which are enclosed in a tire. To create a tire in this case, it is no longer porcelain or polymers that are used, but a fiberglass pipe onto which a shell of tracking-resistant silicone rubber is pressed. In addition, the varistor column has aluminum leads that are pressed on both sides and also screwed inside the pipe.
