Every year, thanks to the efforts of scientists, as well as developers, designers of equipment, devices, component parts of APS installations / systems, the number of the most varied in appearance, quality, as a rule, of a plastic case; functional, often combined, principle of action, purpose is steadily growing.

To understand this diversity, it is worth generalizing knowledge about what they are needed for, first of all, by customers; who invest, let's say frankly, very significant sums in the design of APS, AUPT installations, for the purchase of equipment, including fire detectors, as a practically indispensable element of the vast majority of fire automation systems; installation and commissioning work, subsequent maintenance.

Appointment

• Detection of signs of a fire in a room as quickly as possible, whether it is a sharp increase / change in temperature, air density or the appearance of an open flame, uncharacteristic for normal conditions of substances in space - soot particles, aerosols, gases.
• Resistance to external influences: both mechanical and technological interference, as well as false alarms associated with them.
• Long service life even in harsh conditions - in the presence of dust, harmful impurities, aggressive environment, high air humidity in the protected premises.

Installation Requirements

First of all, you need to understand where you need to install, and what kind / type of fire detectors are. Standards - establishing the rules for the design of installations / systems APS / AUPT, say the following about this:

• The choice of the type / types of fire detectors is carried out in direct dependence on the functional purpose of the room / building, as well as the type of fire load.
• The choice is limited to three types of fire detectors - heat, smoke, flame.

More accurate information on the choice can be obtained by studying Appendix M to this joint venture, where all the main types of premises of buildings / structures are presented, depending on their functional purpose, the corresponding fire detectors.

Views

In fact, apart from the numerous, different combinations / modifications, there are still three main types of such devices for detecting a fire source in premises:

• ... Having not given up their positions for more than a century, such products are still in demand for the protection of premises / buildings, where, due to the properties of raw materials, semi-finished products or finished commercial products, a fire will be accompanied by the release of a huge amount of thermal energy, and not smoke. In addition, such devices, unlike the other two types, are insensitive to ionizing / electromagnetic radiation / effects, other technological interference, the presence of moisture, dust, gas pollution in the airspace of the premises where they are installed.

• ... Detection of signs of fire by the appearance of smoke / soot particles in the air. Designed mainly for the protection of premises in public, residential buildings, where the fire load is characterized mainly by the emission of smoke during combustion (combustible decoration, furniture, documentation, clothing). The most modern, sensitive fire detection devices in this type are.

• ... Determine the appearance of an open fire. There are two types: ultraviolet and infrared flame detectors. Designed to protect both premises of large volumes / heights (hangars, machine rooms), and open technological, storage areas, nodes / control stations of pipeline transport with the presence of flammable / combustible liquids, combustible gases.

• . This is, as a rule, a mechanical alarm button, when pressed, a signal about the occurrence of a fire detected by an eyewitness of this event goes to the premises of the fire / security post / station, the fire department control panel.

Types

In each type of such devices, various types, modifications are developed, embodied in metal and plastic; differing not only in design features or appearance, but in the very principle of fire detection.

It is worth giving an example of such significant differences within one type on heat detectors, which today "track down" a fire in two ways:

• The first is the most "ancient", but it still works without failure today - upon reaching the critical / threshold temperature value in space, as a rule, directly under the ceiling of the protected premises, "prescribed" in the physical characteristics / mechanism of action. It can be a thermal relay or a drop of low-melting solder connecting two contacts in the simplest design of such a device, called.
• The second method is to detect an incipient fire by a sharp rise in temperature per unit of time (per minute). Sensors based on this principle are called.
• Most modern models of products from many manufacturers combine both methods. These are the most sensitive, reliable devices, since they combine two tactics for detecting a fire source based on any change in room temperature.

Similar examples of different types, principles / methods of fire detection can be given by considering smoke detectors. They can be aspirating sensors for the smallest particles of soot, aerosols and other combustion products of organic substances / materials.

But, this is far from a complete classification of fire detectors. Indeed, in addition to the above types / types, they are also divided:

• By the method of detecting the exact location / fire detection in the protected premises of the building / structure - as well as USPAA-1.
• According to the degree of protection of the housing / shell, places of entry of wires / cables from moisture, dust, explosive air-gas / aerosol environment in the premises where they are mounted - fire detectors or in the usual version for installation in buildings with normal conditions.

Again, one should not forget that in pursuit of an outstanding / different housing design from all other manufacturers, the general appearance of detectors of different types, their modifications, often differs so much from the usual / standard forms / outlines; that they can be mistaken for the latest video surveillance devices, burglar alarms, fire extinguishing, sound / lighting equipment, but not for APS sensors.

And it is also often very difficult without reading the accompanying documentation - a technical passport, a description of a device, a manufacturer's instructions or explanations of knowledgeable people - consultants of a trade organization supplying APS equipment or specialists of installation and commissioning enterprises to understand what kind of sensor is installed on the ceiling / wall or exhibited as product sample.

Designation

It looks like a specific set of letters / numbers:

PI х1х2х3, where х1 is a sign of fire that it controls: 1 - heat, 2 - smoke, 3 - flame, 5 - manual.

The next position - х2х3, informs the principle of operation of the sensor. For example, IP 104 stands for a heat detector using a fusible sensor, IP 212 is an optical smoke detector.

Graphically, the sign of a fire detector should be depicted in accordance with , which provides examples of the correct application of all elements of fire alarm systems, fire extinguishing, video surveillance.

Security and fire alarm systems (FSA) are designed to determine the fact of unauthorized entry into a guarded object or the appearance of signs of fire, to issue an alarm and turn on executive devices (light and sound annunciators, relays, etc.). OPS systems are very close to each other in terms of the ideology of construction, and at small objects, as a rule, they are combined on the basis of a single control unit - a receiving and control device (PPK) or a control panel (CP). In general, these systems include:

• detection equipment (detectors);
• technical means for collecting and processing information (receiving and controlling devices, notification transmission systems, etc.);
• technical means of notification (sound and light annunciators, modems, etc.).

Detection technology- these are detectors built on various physical principles of action. A detector is a device that generates a certain signal when one or another monitored environmental parameter changes. According to the field of application, the detectors are divided into security, security and fire and fire. Currently, security and fire detectors are practically not produced and are not used. Security detectors by the type of controlled area are divided into point, linear, surface and volumetric. According to the principle of action - on electrical contact, magnetic contact, shock contact, piezoelectric, optoelectronic, capacitive, sound, ultrasonic, radio wave, combined, combined, etc.

Fire detectors are divided into manual and automatic detectors. Automatic fire detectors are subdivided into heat detectors that respond to an increase in temperature, smoke detectors that respond to the appearance of smoke, and flame that respond to optical radiation from an open flame.

Security detectors

Electrical contact detectors- the simplest type of security detectors. They are a thin metal conductor (foil, wire), specially fixed on a protected object or structure. Designed to protect building structures (glass, doors, hatches, gates, non-capital partitions, walls, etc.) from unauthorized penetration through them by destruction.

Magnetic contact (contact) detectors designed to block various building structures from opening (doors, windows, hatches, gates, etc.). The magnetic contact detector consists of a sealed magnetically operated contact (reed switch) and a magnet in a plastic or metal non-magnetic housing. The magnet is installed on a movable (opening) part of a building structure (door leaf, window sash, etc.), and a magnetically controlled contact is installed on a fixed one (door frame, window frame, etc.). To block large opening structures (sliding and swing gates) with significant backlash, electrical contact detectors such as travel limit switches are used.

Shock detectors They are designed to block various glazed structures (windows, showcases, stained-glass windows, etc.) for breaking, The detectors consist of a signal processing unit (BFB) and from 5 to 15 glass break sensors (DRS). The location of the component parts of the detectors (BFB and DRS) is determined by the number, relative position and area of ​​the blocked glass sheets.

Piezoelectric detectors designed to block building structures (walls, floors, ceilings, etc.) and individual items (safes, metal cabinets, ATMs, etc.) for destruction. When determining the number of detectors of this type and the place of their installation on the protected structure, it is necessary to take into account that it is possible to use them with 100% or 75% coverage of the blocked area. The area of ​​each unprotected area of ​​the blocked surface should not exceed 0.1 m 2.

Optoelectronic detectors are subdivided into active and passive. Active optoelectronic detectors generate an alarm notification when the reflected flow (single-position detectors) changes or the received flow (two-position detectors) stops (changes) of infrared energy caused by the movement of the intruder in the detection zone. The detection zone of such detectors has the form of a "beam barrier" formed by one or more parallel narrowly directed beams located in a vertical plane. The detection zones of different detectors differ, as a rule, in the length and number of beams. Structurally active optoelectronic detectors, as a rule, consist of two separate units - a radiation unit (BI) and a receiver unit (BP), separated by a working distance (range).

Active optoelectronic detectors are used to protect internal and external perimeters, windows, showcases and approaches to individual items (safes, museum exhibits, etc.).

Passive optoelectronic detectors are the most widespread, since, with the help of specially designed optical systems (Fresnel lenses), it is possible to simply and quickly obtain detection zones of various shapes and sizes and use them to protect rooms of any configuration, building structures and individual objects. ...

The principle of operation of the detectors is based on recording the difference between the intensity of infrared radiation emanating from the human body and the background ambient temperature. The sensitive element of the detectors is a pyroelectric converter (pyroreceiver), on which infrared radiation is focused using a mirror or lens optical system (the latter are the most widespread).

The detection zone of the detector is a spatial discrete system consisting of elementary sensitive zones in the form of beams located in one or several tiers or in the form of thin wide plates located in a vertical plane (“curtain” type). Conventionally, the detection zones of detectors can be divided into the following seven types: wide-angle single-tier “fan” type; wide-angle multi-tiered; narrowly directed "curtain" type, narrowly directed "beam barrier" type; panoramic single-storey; panoramic multi-tiered; conical multi-tiered.

Due to the possibility of forming detection zones of various configurations, passive infrared optoelectronic detectors have universal application and can be used to block volumes of premises, places of concentration of valuables, corridors, internal perimeters, aisles between shelves, window and door openings, floors, ceilings, rooms with small animals, warehouses, etc.

Capacitive detectors designed to block metal cabinets, safes, individual items, create protective barriers. The principle of operation of the detectors is based on a change in the electrical capacity of the sensitive element (antenna) when a person approaches or touches a protected object. In this case, the protected object must be installed on a floor with a good insulating covering or on an insulating pad.

It is allowed to connect several metal safes or cabinets to one detector in a room. The number of connected items depends on their capacity, design features of the room and is specified when setting up the detector.

Sound (acoustic) detectors are designed to block glazed structures (windows, shop windows, stained-glass windows, etc.) for breaking. The principle of operation of these detectors is based on a non-contact method of acoustic control of the destruction of a glass sheet by vibrations arising during its destruction in the sound frequency range and propagating through the air.

When installing the detector, all areas of the protected glazed structure must be within its direct view.

Ultrasonic detectors are designed to block volumes of enclosed spaces, The principle of operation of the detectors is based on the registration of disturbances in the field of elastic waves of the ultrasonic range, created by special emitters, when moving in the area of ​​human detection. The detection area of ​​the detector has the shape of an ellipsoid of rotation or a teardrop shape.

Due to the low noise immunity, they are currently practically not used.

Radio wave detectors designed to protect enclosed spaces, internal and external perimeters, individual items and building structures, open areas. The principle of operation of radio wave detectors is based on the registration of disturbances of electromagnetic waves of the microwave range, emitted by the transmitter and registered by the receiver of the detector when a person moves in the detection zone. The detection zone of the detector (as in the case of ultrasonic detectors) has the shape of an ellipsoid of rotation or a drop-shaped shape, The detection zones of different detectors differ only in size.

Radio wave detectors are one - and two-position. Single-position detectors are used to protect volumes of closed rooms and open areas. Two-position - for perimeter protection.

When choosing, installing and operating radio wave detectors, one should remember one of their features. For electromagnetic waves of the microwave range, some building materials and structures are not an obstacle (screen) and they freely, with some attenuation, penetrate through them. Therefore, the detection zone of the radio wave detector can, in some cases, go beyond the protected premises, which can cause false alarms. Such materials and structures include, for example, thin plasterboard partitions, windows, wooden and plastic doors, etc. Therefore, radio wave detectors should not be aimed at window openings, thin walls and partitions, behind which during the security period the movement of large objects and people is possible. It is not recommended to use them on objects near which powerful radio transmitting means are located.

Combined detectors are a combination of two detectors built on different physical principles of detection, structurally and schematically combined in one housing. Moreover, they are schematically combined according to the "and" scheme, that is, only when both detectors are triggered, an alarm is generated. The most widely used combination of passive infrared and radio wave detectors.

Combined security detectors have a very high noise immunity and are used to protect premises of objects with complex interference conditions, where the use of other types of detectors is impossible or ineffective.

Combined detectors are two detectors built on different physical principles of detection, structurally combined in one housing. Each detector works independently of the other and has its own detection zone and its own output for connection to the alarm loop. The most widely used combination of infrared passive and acoustic detectors. There are other combinations as well.

Alarm detectors are intended for manual or automatic submission of an alarm notification to the internal security console of the facility or to the internal affairs bodies in cases of a possible criminal attack on employees, customers or visitors of the facility.

Various buttons and pedals of hand and foot action based on magnetic and electrical contact detectors are used as alarms. As a rule, such detectors are fixed in the pressed state and return to their original position is possible only with a key.

For the same purposes, special mini-alarm systems operating over a radio channel have been developed and are being used. They include a receiver that can be connected to the control panel or control panel, and several wearable transmitters for wireless transmission of alarm messages. Some key fobs include a drop sensor. The range of such systems is from several tens to several hundred meters.

Trap detectors occupy a special place among alarm detectors. They are designed to alert you when you try to steal money or rob a guarded object, regardless of the actions of the personnel. They represent an imitation of a wad of money in a bank package with a volume of 100 bills, into which a magnet is mounted, and a magnetic sensor (reed switch) in a special stand on which the bundle is located.

When the imitation bundle of money is withdrawn (moved) from the stand, the contacts of the magnetic sensor are opened and an alarm is sent to the security console of the facility. There are similar trap detectors, where a special cartridge containing colored (orange) smoke with a volume of 5 m is built in together with a magnet. 2 The smoke composition is sprayed with a time delay (3 minutes) after the magnetic sensor is triggered.

Types of interference and their possible sources

During operation, detectors are exposed to various interfering factors, among which the main ones are: acoustic interference and noises, vibrations of building structures, air movement, electromagnetic interference, changes in temperature and humidity of the environment, technical weakness of the protected object.

The degree of influence of interference depends on their power, as well as on the principle of operation of the detector.

Acoustic interference and noise are created by industrial installations, vehicles, household radio equipment, lightning discharges and other sources. Examples of acoustic interference are given in table 1.

Table 1. Examples of acoustic interference

This type of interference causes the appearance of inhomogeneities in the air environment, vibrations of not rigidly fixed glazed structures and can cause false alarms of ultrasonic, sound, shock-contact and piezoelectric detectors. In addition, the operation of ultrasonic detectors is influenced by high-frequency components of acoustic noise.

Vibration of building structures caused by trains and subway trains, powerful compressor units, etc. Shock and piezoelectric detectors are especially sensitive to vibration interference, therefore, these detectors are not recommended to be used on objects subject to such interference.

Air movement in the protected area is caused mainly by heat flows near heating devices, drafts, fans, etc. The most susceptible to the influence of air flows are ultrasonic and passive optoelectronic detectors. Therefore, these detectors should not be installed in places with noticeable air movement (in window openings, near central heating batteries, near ventilation openings, etc.).

Electromagnetic interference are created by lightning discharges, powerful radio transmitting means, high-voltage power lines, distribution power supply networks, electric transport contact networks, installations for scientific research, technological purposes, etc.

Radio wave detectors are most susceptible to electromagnetic interference. Moreover, they are more susceptible to radio interference. The most dangerous electromagnetic interference is power supply interference. They arise when switching powerful loads and can penetrate into the input circuits of the equipment through the power supply inputs, causing its false alarms. A significant decrease in their number gives the use and timely maintenance of backup power supplies.

Eliminating the impact of electromagnetic interference of AC networks on the operation of detectors allows compliance with the basic requirement for the installation of low-voltage connecting lines: the laying of the power supply lines of the detector and the alarm loop must be parallel to the power networks at a distance of at least 50 cm between them, and their intersection must be at right angles.

Changes in ambient temperature and humidity at a protected facility can influence the operation of ultrasonic detectors. This is due to the fact that the absorption of ultrasonic vibrations in air is highly dependent on its temperature and humidity. For example, when the ambient temperature rises from +10 to +30 ° C, the absorption coefficient increases by 2.5-3 times, and when the humidity rises from 20-30% to 98% and decreases to 10%, the absorption coefficient changes by 3-4 times.

A decrease in the temperature at the object at night compared to daytime leads to a decrease in the absorption coefficient of ultrasonic vibrations and, as a consequence, to an increase in the detector's sensitivity. Therefore, if the detector was adjusted during the daytime, at night, sources of interference that were outside this zone during the adjustment period can enter the detection zone, which can trigger the detector.

Technical laxity of facilities has a significant effect on the stability of the operation of magnetic detectors used to block elements of building structures (doors, windows, transoms, etc.) for opening. In addition, poor technical strength can cause false alarms of other detectors due to drafts, vibrations of glazed structures, etc.

It should be noted that there are a number of specific factors that cause false alarms for detectors of only a certain category. These include: the movement of small animals and insects, fluorescent lighting, radio transmission of building structure elements, direct sunlight and car headlights on detectors.

Small animals and insects movement can be perceived as the movement of an intruder by detectors, the principle of which is based on the Doppler effect. These include ultrasonic and radio wave detectors. The influence of crawling insects on the detectors can be eliminated by treating their installation sites with special chemicals.

When fluorescent lighting is used at an object guarded by radio wave detectors, the source of interference is a column of ionized gas of the lamp blinking at a frequency of 100 Hz and vibration of the lamp armature at a frequency of 50 Hz.

In addition, fluorescent and neon lamps create continuous fluctuation noise, while mercury and sodium lamps create pulsed noise with a wide frequency spectrum. For example, fluorescent lamps can create significant radio interference in the frequency range of 10-100 MHz or more.

The detection range of such light sources is only 3-5 times less than the detection range of a person, therefore, during the period of protection, they must be turned off, and incandescent lamps should be used as emergency lighting.

Radio transmission of building structure elements can also cause a false triggering of a radio wave detector if the walls are thin or there are large-sized thin-walled openings, windows, doors.
The energy emitted by the detector can escape outside the premises, while the detector detects people passing outside, as well as passing vehicles. Examples of radio transmission of building structures are given in Table 2.

Table 2. Examples of radio transmission of building structures

Thermal radiation from lighting fixtures can cause false alarms of passive optoelectronic detectors. This radiation in terms of power is comparable to the thermal radiation of a person and can cause the detectors to trigger.

In order to eliminate the effect of these interferences on passive optoelectronic detectors, it is possible to recommend isolating the detection zone from the effects of radiation from lighting devices. Reducing the influence of interfering factors, and, consequently, reducing the number of false alarms of detectors, is mainly achieved by observing the requirements for the placement of detectors and their optimal configuration at the installation site.

V Table 3 the types and sources of interference and the ways of their elimination are given.

Table 3. Sources of interference and how to eliminate them

When choosing the types and number of detectors for the protection of a specific facility, one should take into account:
- the required level of security of the facility;
- expenses for the purchase, installation and operation of the detector;
- construction and structural characteristics of the object;
- tactical and technical characteristics of the detector.
The recommended type of detector is determined by the type of structure to be blocked and the method of physical impact on it in accordance with Table 4.

Fire detectors

Fire detectors are the main elements of automatic fire and security fire alarm systems.

According to the method of activation, fire detectors are divided into manual and automatic. Manual detectors lack the function of detecting a fire source, their action is reduced to transmitting an alarm message to the electrical circuit of the alarm loop after a person detects a fire and activating the detector by pressing the corresponding start button.

Automatic fire detectors operate without human intervention. With their help, the detection of ignition is carried out by one or several analyzed signs and the formation of a fire notification when the controlled physical parameter of the set value is reached. Elevated air temperature, release of combustion products, turbulent flows of hot gases, electromagnetic radiation, etc. can be monitored parameters. The use of other signs of fire is also possible. Combined detectors react to two or more parameters that characterize the appearance of a fire source.

Heat detectors can use the method of forming the analyzed signal, which allows them to respond not only to an increase in the absolute value of temperature above the maximum set threshold, but also to an excess of the slew rate of its limit value. Therefore, in accordance with the nature of the reaction to a change in the controlled attribute, they are divided into maximum, differential and maximum-differential. Smoke fire detectors, according to the principle of operation, are divided into optoelectronic and ionization.

According to the method of power supply, fire detectors are divided into:

• powered by the alarm loop from the control panel or control panel;
• powered by a separate external power supply;
• powered by a built-in internal power source (autonomous fire detectors).

The detector's detection zone is the space near the detector, within which it is guaranteed to be triggered when a fire occurs. Most often, this parameter is expressed in units of area (m 2) controlled by the detector with the required reliability. With an increase in the height of the detector installation, the area controlled by one detector decreases. If the installation height is higher than the specified maximum, the effective detection of the fire source by the detector is not guaranteed.

For light detectors, the protected area is determined by the maximum detection range of an open test fire and the viewing angle, which depends on the design of the optical system.

Fire detectors must ensure reliable detection of a fire source in specific protected areas. To do this, when choosing a detector, it is necessary to take into account the probable nature of ignition and the development process over time of the main fire factors: temperature rise, smoke concentration, light radiation at various points in the room. Depending on the type and amount of combustible materials in the event of a fire, there may be a predominance of one or more detectable signs.

Most often, ignition is accompanied by the release of smoke in the initial stage, therefore, in most cases, the use of smoke detectors is most advisable. When choosing a smoke detector, it should be borne in mind that ionization (radioisotope) and optoelectronic smoke detectors have different sensitivity to combustion products, the smoke particles of which have different colors and sizes. Optoelectronic point detectors respond better to light smoke, typical of cellulose-containing materials, as well as smoke consisting of small aerosol particles. Ionization detectors have a relatively higher sensitivity to combustion products emitting black smoke with larger particles (for example, when burning rubber).

Premises, in which the rapid appearance of an open flame is most likely during a fire, should preferably be equipped with light detectors.

It is advisable to install heat detectors, first of all, in those cases when a significant power of the fire center is provided and, therefore, an intense heat release will occur in the event of a fire.

When choosing a detector, it is also necessary to take into account special additional requirements for their design and principle of operation. For example, it is not recommended to install radioisotope detectors in residential premises and childcare facilities. In hazardous areas, detectors with a special design must be installed.

The calculation of the total number of detectors and the determination of their installation locations should be carried out taking into account the characteristics of the room, as well as the requirements of regulatory and technical documentation. The latter includes the relevant documents regulating general issues of design and installation of fire automation installations, systems and complexes of fire and burglar alarms, as well as operational documentation for the corresponding type of detector.

More and more widespread are fire detectors created using the element base of the fourth generation: specialized controllers and microprocessors.

A common feature of such detectors with extended tactical and technical capabilities is the use of only special devices (control panels) that are part of the security and fire alarm system of the corresponding company for joint operation.

The use of computer technology makes it possible to create addressable fire detectors that transmit information about their location to the central processor of the control panel, which ensures an accurate reconstruction of the picture and analysis of the process of the emergence and development of a fire. They carry out automatically or at the request of the center, the performance monitoring and digital transmission of data on the parameters of their functioning. In such detectors, if necessary, it is possible to adjust the sensitivity when the environmental conditions change. Analog detectors can also transmit information about the level of the monitored parameter. The expansion of the range of detectors is carried out through the use of new technologies. For example, modern foreign linear heat detectors (cable type) detect the difference between normal and elevated temperatures, which makes it possible to generate an alarm even before the start of a fire (smoke or fire) when the monitored object overheats. The signal is transmitted in analog form from the detector to a special control panel, which allows you to determine the distance to the overheated area. Such detectors can be effectively used to control objects with electrical equipment, rooms with false ceilings, cable routes and channels.

Technical means of collecting and processing information

The technical means for collecting and processing information include receiving and monitoring devices, control panels, signaling and starting devices, notification transmission systems, etc. They are designed for continuous collection of information from technical means of detection (detectors) included in the alarm loops, analysis of an alarm situation at the facility and its display, control of local light and sound annunciators, indicators and other devices (relay, modem, transmitter, etc.). ), as well as the formation and transmission of notifications about the state of the object to the central post or the centralized monitoring panel, They also provide the delivery and disarming of the object (room) according to the adopted tactics, as well as in some cases the power supply of the detectors.

Receiving and control devices are classified according to information capacity (the number of controlled alarm loops) into devices of small (up to 5 AL), medium (from 6 to 50 AL) and large (over 50 AL) information capacity. In terms of information content, devices can be small (up to 2 types of notifications), medium (from 3 to 5 types) and large (over 5 types) information content.

Notification transmission systems are classified according to information capacity (the number of protected objects) into systems with constant information capacity and with the possibility of increasing information capacity.

In terms of information content, the systems are subdivided into systems of small (up to 2 types of notifications), medium (from 3 to 5 types) and large (over 5) information content.

According to the type of communication lines (channels) used, the systems are subdivided into systems using telephone network lines (including switchable ones), special communication lines, radio channels, combined communication lines, etc.

According to the number of directions of information transmission, they are subdivided into systems with one- and bi-directional information transmission (with the presence of a reverse channel).

According to the object maintenance algorithm, message transmission systems are subdivided into non-automated systems with manual tactics of arming (disarming) objects under protection (disarming) after telephone conversations with the control panel attendant and automated systems with automatic arming and disarming (without telephone conversations).

According to the method of displaying the information coming to the centralized observation panel, the notification transmission systems are subdivided into systems with individual or group display of information in the form of light and sound signals, with information being displayed on the display using devices for processing and storing a database.

In terms of the main tasks being solved, the control panels correspond to domestic control devices. Let us also clarify the concepts of a protection zone (a term used in foreign literature) and an alarm loop used in domestic literature. Let us note right away that these concepts are different.

Alarm loop Is an electrical circuit that connects the output circuits of the detectors, which includes auxiliary elements (diodes, resistors, etc.), connecting wires and boxes and is designed to issue notifications about intrusion, attempted intrusion, fire, malfunction, and in some cases and to supply power to the detectors.

Thus, the alarm loop is designed to monitor the status of a certain protected zone.

Zone- this is a part of the protected object controlled by one or more alarm loops. Therefore, the term "zone" used in the descriptions of foreign equipment is in this case synonymous with the term "alarm loop".

Modern multifunctional control points have ample opportunities for organizing security, fire and security and fire alarm systems. Knowledge of these possibilities will make it possible to make the right choice of a checkpoint, the characteristics and parameters of which most fully satisfy the solution of the assigned tasks for the protection of a particular object.

The structure of the alarm system, organized on the basis of the CP, will largely be determined by the method of connecting the alarm loops, which affects the functional characteristics of the organized security system and largely determines the cost of installation work. By the method of connecting the loops, the following types of CP can be distinguished:

• with trains of radial structure;
• with a tree structure;
• addressable.

In a control panel with radial loops, each loop is connected directly to the panel itself. Such a structure justifies itself with a small number of loops (usually up to 16) and at facilities that do not require the organization of remote loops. They are usually used for small and medium-sized facilities.

CPs with a tree structure have a special information bus of several wires (usually 4). Expanders are connected to this bus. In turn, radial loops are connected to the expanders. Several basic radial loops can also be connected to the CP itself. The total number of loops is usually in the range of 24-128. Expanders monitor the status of the loops connected to them, encode information about their status and transmit it via the data bus to the control panel, which has an indication of the status of all loops. Such checkpoints are used to build security systems for medium and large facilities.

Addressable control panels using loops with addressable detectors stand somewhat apart from the rest and are usually used to create rather complex integrated security systems for large and critical facilities. Obviously, addressable detectors are more complicated and more expensive than conventional ones, and their use and advantages are fully manifested in complex and large objects.

There are addressable CPs that have different designs of their loops:

• beam;
• annular;
• annular with ray branches.

The ring train has a rather serious advantage. If it is damaged (broken), it retains its operability, since the information exchange line is preserved. When the loop is closed, special devices, loop dividers, disconnect the short-circuited section, and the rest of the loop continues to function.

Receiving and control devices (PPK) and control panels (CP) are the main elements that form an information and analytical system of security, fire or security and fire alarms at the facility. Such systems can be autonomous or centralized. In the first case, the PPK or KP is installed in the security room (point) located at the guarded facility. With centralized security, an object complex of technical means, formed by one or several PPK (CP), forms an object subsystem of the security and fire alarm system, which, using the notification transmission system (SPI), transmits in a given form information about the state of the object to the centralized monitoring station (CMS), located in the center for receiving alarm notices (centralized security point - ARC). The information generated by the PPK or CP during autonomous and centralized protection is transmitted to employees of special security services of the facility, which are entrusted with the functions of responding to alarms received from the facility.

Key terms used in the section:

1. Detector detection area- part of the protected object space, in which the detector issues an alarm message when the controlled parameter exceeds the threshold value.
2. Detector sensitivity- the numerical value of the monitored parameter, when exceeded, the detector should be triggered.
3. Optical density of the medium- the decimal logarithm of the ratio of the radiation flux passing through a non-smoky medium to the radiation flux attenuated by the medium during its partial or complete smoke.

reference Information

Requirements for the placement of fire detectors in accordance with NPB 88-2001 “Fire extinguishing and alarm installations. Norms and rules of design "

In accordance with NPB 88-2001 “Fire extinguishing and alarm installations. Norms and rules of design ", the area controlled by one point smoke detector, as well as the maximum distance between the detectors and the wall, must be determined by table 5

Table 5. Requirements for the placement of smoke detectors

When monitoring the protected area with two or more smoke linear detectors (LDPI), the maximum distance between their parallel optical axes, the optical axis and the wall, depending on the installation height of the fire detector units, should be determined by Table 6.

Table 6. Requirements for the placement of smoke line detectors

In rooms with a height of over 12 m and up to 18 m, the detectors should be installed in two tiers, in accordance with Table 7.

Table 7. Requirements for the placement of smoke linear detectors for two-tier placement

The area monitored by one point heat detector, as well as the maximum distance between the detector and the wall, must be determined by Table 8, but not exceeding the values ​​specified in the technical specifications and passports for the detectors.

Table 8 Requirements for the placement of heat detectors

Classes of thermal fire detectors, in accordance with NPB 85-2000 “Heat fire detectors. Fire safety technical requirements. Test methods "

In accordance with NPB 85-200 “Heat fire detectors. Fire safety technical requirements. Test methods ", maximum, maximum differential detectors and detectors with a differential characteristic, depending on the temperature and response time, are divided into ten classes: A1, A2, A3, B, C, D, E, F, G, H (see ... Table 9).

Table 9. Classes of maximum differential detectors

The statistics of offenses related to the penetration of intruders into the guarded premises, says that the most "popular" and simplest is breaking glass of shop windows, windows, as well as breaking locks or doors. The likelihood of such a scenario, according to experts, is now 66.5%. Only a wall break can slightly compete with breaking window openings and breaking doors (16.9%), other options (selection of keys, breaking the ceiling, penetration through technological openings) barely exceed 5%.

Who is he, the keeper of doors and windows

To reliably protect doors, windows, gates, technological openings and other structures from the threat of damage or burglary by intruders, adequate technical security equipment was required. Magnetic contact detectors have become such means, among which the most prominent position is occupied by a security point magnetic contact detector - a reliable and easy-to-install sensor. Experts give him a high assessment in terms of the probability of detecting an attempt to enter the territory of the object protected by this device: it is 0.99, that is, in 99% of cases the criminal will be detected by the sensor and the corresponding signal will go to the control panel of the guard on duty.

With the help of such sensors, it is possible not only to supply an electrical signal to turn on an audible alarm, but also to turn on devices that block doors (gates), windows for opening, and objects for movement.

Protected structures can be made of both magnetic (iron) and non-magnetic material (wood, aluminum, fiberglass, polyvinyl chloride). This does not affect the operation of the magnetic contact.

The principle of construction and the device of the detector

It is in the principle of the sensor construction that its high reliability is laid. Here, the interaction of a sealed magnetically controlled contact (abbreviated as a reed switch), which serves as an actuator, and a magnet, which serves as a control element, is used.

The actuator (reed switch) has a very simple design: it immediately combines contact and magnetic systems, which are hermetically sealed in a glass container. This design of the reed switch made it possible to obtain characteristics that surpass the known contacts: speed, stable parameters, high wear resistance and reliability.

The contacts are made of soft magnetic material, they are separated by a gap of only 300-500 microns, which has certain disadvantages: increased sparking and increased contact resistance. This leads to a sudden "sticking" of contacts and failure of the detector.

Since there are no intermediate links in the reed switch of the detector, and the contacts switch a small electric current, the actuator has almost zero wear. This is also facilitated by the fact that there is nitrogen in the cylinder under high pressure, which excludes oxidation of the contacts.

The control (master) element can be made in several versions: or a magnetic circuit.

Classification of magnetic detectors

Detectors, like any other equipment, are subject to standardization, and this task is solved by the international standard IEC 62642-2-6. Its requirements apply to magnetic contact detectors designed to block doors, hatches, windows, containers.

This standard introduces four risk classes for these sensors: 1 - low risk, 2 - intermediate risk between 1 and 3 classes, 3 - medium risk, 4 - high risk.

The given classification defines the critical and non-critical parameters of the detector for each class. For example, trip and recovery distances, protection against damage to the alarm loop and complete loss of supply voltage should be mandatory parameters for all four classes.

In the Russian Federation, detectors of 1 or 2 class of the international standard IEC 62642-2-6 are used, that is, they do not have to indicate the detection of damage to the protected structure, protection from extraneous magnetic influences, low supply voltage.

Requirements for the functionality of magnetic contact detectors

Magnetic detectors must meet certain requirements for their functionality, namely:

• the sensing distance excludes an intruder's attempt to penetrate through the monitored structure or the movement of the guarded object, as well as the replacement of detector parts without giving an alarm signal;
• the recovery distance must exclude false triggering of the detector. - the relative displacement of the detector blocks (alignment) should not lead to the termination of its operation;

The indicators of the functionality of magnetic contact detectors depend on the type of sensor, its size, installation location, material of the protected structure.

Sensor marking

The magnetic contact sensor has a standardized name - magnetic contact point burglar detector EUT. This is followed by a digital code characterizing the detection zones and the principle of the detector.

For example, a magnetic contact detector IO 102 (SMK) is labeled IO 102, which indicates that this equipment belongs to the type of detectors (letter I), is used in security systems (letter O), has a point detection zone (number 1) and a magnetic contact principle actions (numbers 0 and 2).

Selecting a detector

The choice of equipment such as a magnetic contact burglar detector EUT is an important step. First of all, it must correspond to the place of installation, the material of the protected structure, the conditions of detention, as well as your requirements.

If it is necessary to protect a detached object, then this task will be performed by a magnetic contact burglar detector IO 102-2 (push-button).

IO 102-20 / A2 is perfect for blocking doors, windows and other elements of the room. He is also able to protect himself from sabotage ("trap"). That is, the noise immunity of the sensor is an important aspect in matters of its choice.
The conditions of the detector should also be taken into account, and if the environment is explosive, then the IO 102-26 / V sensor is suitable for it.

The sensor is designed for air temperatures from minus 40 to plus 50 degrees Celsius.

Attention is also drawn to the characteristics of the reed switch: they must correspond to your conditions.

Installing the detector blocks

The magnetic contact point detector and the alarm loop are attached to the surface of the protected structure from the side of the room. The control element is mounted, as a rule, on a moving part of the structure (door, window, cover), and the executive unit with an alarm loop - on a stationary one (door frame, frame, body).

The way of fixing the detector depends on the surface on which it is being installed: on wood - with screws, on metal - with screws, on glass - with "Contact" glue. A dielectric spacer must be installed between the detector blocks and the mounting surface.

The described mounting method refers to the open type, but in some cases it becomes necessary to mount the sensor in a hidden way. For this, there are cylindrical detectors. The very shape of the sensor allows you to install it secretly from prying eyes and not disturb the interior of the room. But this type of installation has a certain drawback: it is fundamentally important to maintain the alignment of the ends of the executive and control elements of the detector (within 2-3 mm).

Sensor sabotage and how to deal with it

According to amateurs, magnetic detectors are easily bypassed, that is, ignored. And this is done, in their opinion, with the help of an external strong magnet.
In reality, this is far from the case, especially when it comes to In this case, sabotage of the sensors is practically impossible, since the steel will close the action of the external magnet on itself, and it will not reach the actuator.

In cases with a non-metallic structure, not everything is simple either: a certain orientation of the external magnet is required, otherwise its impact on the actuator can cause the reed switch to open and trigger the alarm.

If these arguments are not convincing, then there are simple ways to protect against sabotage of detectors:

• the use of two sets of magnetic contact sensors with multidirectional magnets spaced about 15 mm from each other and connected in series;
• use of an additional screen in the form of a steel plate with a thickness of 0.5 mm or more;

Briefly about the disadvantages

The magnetic contact detector SMK has certain features of the actuator that limit its use:

• the dependence of pressing the contacts on the strength of the magnet of the control element and the control current;
• the dependence of the switching capacity on the volume of the reed switch cylinder;

the length of the contacts contributes to their significant bounce during vibration and shock;

Conclusion

The magnetic contact detector IO is deservedly considered the simplest and most reliable means of protecting objects and structures from intruders. A significant advantage of the sensor is its low cost. Security systems containing this type of detectors are often preferred. Today there are many security systems created using innovative technologies, but magnetic contact detectors are still in demand.

Study of the main characteristics of optoelectronic, vibration, capacitive, wire means for detecting unauthorized intrusions into protected objects.

2. Theoretical information.

Technical means of detection are detectors built on various physical principles of operation. A detector is a device that generates a certain signal when one or another monitored environmental parameter changes. According to the field of application, the detectors are divided into security, security and fire and fire. Currently, security and fire detectors are practically not produced and are not used. Security detectors according to the type of controlled area are divided into point, linear surface and volumetric. According to the principle of action - on electrical contact, magnetic contact, shock contact, piezoelectric, optoelectronic, capacitive, sound, ultrasonic, radio wave, combined, combined, etc.

Fire detectors are divided into manual and automatic detectors. Automatic fire detectors are subdivided into heat detectors that respond to an increase in temperature, smoke detectors that respond to the appearance of smoke, and flame that respond to optical radiation from an open flame.

Security detectors.

Electrical contact detectors- the simplest type of security detectors. They are a thin metal conductor (foil, wire) fixed in a special way on a protected object or structure. Designed to protect building structures (glass, doors, hatches, gates, non-capital partitions, mills, etc.) from unauthorized entry through them by destruction.

Magnetic contact (contact) detectors designed to block various building structures from opening (doors, windows, hatches, gates, etc.). The magnetic contact detector consists of a sealed magnetically operated contact (reed switch) and a magnet in a plastic or metal non-magnetic housing. The magnet is installed on the movable (opening) part of the building structure (door leaf, window sash, etc.), and the magnetically controlled contact is installed on the stationary one (door frame, window frame, etc.). To block large opening structures - sliding and swing gates with significant backlash, electrical contact detectors such as travel limit switches are used.

Shock detectors are designed to block various glazed structures (windows, showcases, stained-glass windows, etc.) for breaking. The detectors consist of a signal processing unit (BFB) and from 5 to 15 glass break sensors (DRS). The location of the component parts of the detectors (BFB and DRS) is determined by the number, relative position and area of ​​the blocked glass sheets.

Piezoelectric detectors designed to block building structures (walls, floor, ceiling, etc.) and individual objects for destruction. When determining the number of detectors of this type and the place of their installation on the protected structure, it is necessary to take into account that it is possible to use them with 100% or 75% coverage of the blocked area. The area of ​​each unprotected area of ​​the blocked surface should not exceed 0.1 m2.

Optoelectronic detectors are subdivided into active and passive. Active optoelectronic detectors generate an alarm notification when the reflected flow (single-position detectors) changes or the received flow (two-position detectors) stops (changes) of infrared energy caused by the movement of the intruder in the detection zone. The detection zone of such detectors has the form of a "beam barrier" formed by one or more parallel narrowly directed beams located in a vertical plane. The detection zones of different detectors differ, as a rule, in the length and number of beams. Structurally active optoelectronic detectors, as a rule, consist of two separate units - a radiation unit (BI) and a receiver unit (BP), separated by a working distance (range).

Active optoelectronic detectors are used to protect internal and external perimeters, windows, showcases and approaches to individual items (safes, museum exhibits, etc.).

Passive optoelectronic detectors are the most widespread, since, with the help of specially designed optical systems (Fresnel lenses), it is possible to simply and quickly obtain detection zones of various shapes and sizes and use them to protect rooms of any configuration, building structures and individual objects.

The principle of operation of the detectors is based on recording the difference between the intensity of infrared radiation emanating from the human body and the background ambient temperature. The sensitive element of the detectors is a pyroelectric converter (pyroreceiver), on which infrared radiation is recorded using a mirror or lens optical system (the latter are the most widespread).

The detection zone of the detector is a spatial discrete system consisting of elementary sensitive zones in the form of beams located in one or several tiers or in the form of wide plates located in a vertical plane (of the "curtain" type). Conventionally, the detection zones of detectors can be divided into the following seven types: wide-angle single-tier "fan" type; wide-angle multi-tiered; narrowly directed curtain type; narrow beam type "beam barrier"; panoramic single-storey; panoramic multi-tiered; conical multi-tiered.

Due to the possibility of forming detection zones of various configurations, passive infrared optoelectronic detectors have universal application and can be used to block volumes of premises, places of concentration of valuables, corridors, internal perimeters, passages between shelves, window and door openings, floors, ceilings, rooms with small animals, warehouses, etc.

Capacitive detectors designed to block metal cabinets, safes, individual items, create protective barriers. The principle of operation of the detectors is based on a change in the electrical capacity of the sensitive element (antenna) when a person approaches or touches a protected object. In this case, the protected object must be installed on a floor with a good insulating covering or on an insulating pad.

It is allowed to connect several metal safes or cabinets to one detector in a room. The number of connected items depends on their capacity, design features of the room and is specified when setting up the detector.

Sound (acoustic) detectors are designed to block glazed structures (windows, shop windows, stained-glass windows, etc.) for breaking. The principle of operation of these detectors is based on a non-contact method of acoustic control of the destruction of a glass sheet by vibrations arising during its destruction in the sound frequency range and propagating through the air.

When installing the detector, all areas of the protected glazed structure must be within its direct view.

Ultrasonic detectors are designed to block volumes of enclosed spaces. The principle of operation of the detectors is based on the registration of disturbances in the field of elastic waves of the ultrasonic range, created by special emitters, when moving in the detection zone of a person. The detection area of ​​the detector has the shape of an ellipsoid of rotation or a teardrop shape.

Due to the low noise immunity, they are currently practically not used.

Radio wave detectors designed to protect enclosed spaces, internal and external perimeters, individual items and building structures, open areas. The principle of operation of radio wave detectors is based on the registration of disturbances of electromagnetic waves of the microwave range, emitted by the transmitter and registered by the receiver of the detector when a person moves in the detection zone. The detection zone of the detector (as in the case of ultrasonic detectors) has the shape of an ellipsoid of rotation or a teardrop shape. The detection zones of different detectors differ only in size.

Radio wave detectors are one and two-position. Single-position detectors are used to protect volumes of closed rooms and open areas. Two-position - for perimeter protection.

When choosing, installing and operating radio wave detectors, one should remember one of their features. For electromagnetic waves of the microwave range, some building materials and structures are not an obstacle (screen) and they freely, with some attenuation, penetrate through them. Therefore, the detection zone of the radio wave detector can, in some cases, go beyond the protected premises, which can cause false alarms.

Combined detectors are a combination of two detectors built on different physical principles of detection, structurally and schematically combined in one housing. Moreover, they are schematically combined according to the "AND" scheme, i.e. only when both detectors are triggered, an alarm is generated. The most widely used combination of passive infrared and radio wave detectors.

Combined security detectors have a very high immunity to interference and are used to protect premises of objects with complex interference conditions, where the use of other types of detectors is impossible or ineffective.

Combined detectors are two detectors built on different physical principles of detection, structurally combined in one housing. Each detector works independently of the other and has its own detection zone and its own output for connection to the alarm loop. The most widely used combination of infrared passive and acoustic detectors. There are other combinations as well.