Heat detector circuit with indication. LLC NPP Magneto-Contact

The appearance of fires is characterized by an increase in ambient temperature. Therefore, heat detectors are most often used in fire alarm systems.

They are able to identify fires at the initial stage, which allows timely measures to be taken to eliminate them. However, such sensors are presented in various modifications on the market.

To choose the right one for a specific room, you should learn as much as possible about them.

Design features of the device

What is a detector? This is a heat-sensitive element enclosed in a plastic case. The operating principle of the simplest models is based on closing/opening contacts, leading to the formation of a signal.

For the device to operate, the ambient temperature must rise above the device’s threshold value.

When operating, such heat detectors do not consume current. They are called passive. They use a specific alloy as a thermoelement. Previously, these sensors were disposable and could not be restored, but today reusable models have appeared. In them, under the influence of temperature, the bimetallic element, changing its shape, affects the contact.

There are magnetically controlled samples. The permanent magnet located in them changes its properties as a result of heating, which leads to the operation of the device.

When selecting a heat detector for a room, it is necessary that the threshold temperature value for them be higher than the average for the building by at least 10 ° C. This allows you to avoid false alarms.

Types of devices and their features

Each device is designed for a specific controlled area. By the nature of its detection on:

• Spot
• Linear

Point thermal fire detectors, in turn, are available in two types:

• Maximum
• Differential

The operation of the former is based on a change in the state of the thermoelement when the temperature rises to a threshold value. It is worth noting that in order to trigger, it is necessary that the detector itself heats up to the value specified in the technical specifications. And this will take some time.

This is an obvious disadvantage of the device, since it does not allow detecting a fire at the initial stage. This can be eliminated by increasing the number of sensors located in one room, as well as using other types of sensors.

Differential heat detectors are designed to monitor the rate of temperature rise. This made it possible to reduce the inertia of the device. The design of such sensors includes electronic elements, which affects the cost.

In practice, most often, these two types are used in combination. Such a maximum differential fire detector is triggered not only by the rate of temperature rise, but also by its threshold value.

Linear devices or thermal cables are twisted pairs, where each wire is coated with a thermo-resistive material. When the temperature rises, it loses its properties, which leads to a short circuit in the circuit and the formation of a fire signal.

The thermal cable is connected instead of the system cable. But it has one drawback - a short circuit can be caused not only by fire.

To eliminate such moments, linear sensors are connected through interface modules that ensure communication with the alarm device. Many of them are used in technological elevator shafts and other similar structures.

Manufacturers - choosing the best model

Thermal sensors from Russian companies are most widely used on the domestic fire-fighting equipment market. This is due to both the characteristics of alarm systems, regulatory requirements, and their reasonable prices.

The most popular are thermal fire alarm detectors:

• Aurora TN (IP 101-78-A1) – Argusspectr
• IP 101-3A-A3R – Siberian Arsenal

The Aurora detector is a maximum differential non-addressable detector. It is used to detect fires in a room and transmit a signal to the control panel.

Watch a video about the product:

The advantages of this model include:

1. High sensitivity
2. Reliability
3. Using a microprocessor as part of the device
4. Easy to maintain

Its cost is more than 400 rubles, but it fully corresponds to the quality of the device.

Explosion-proof thermal detectors IP 101-3A-A3R are also classified as maximum differential. They are intended for use in heated rooms and can work with DC and AC loops.

The advantages of this model include:

• Electronic control circuit
• The presence of an LED indicator that allows you to monitor the operation of the device
• Modern design

The cost of this model is significantly lower and amounts to 126 rubles, which makes them accessible to a wide range of users.

Watch a video about IP 101-7 explosion-proof products:

There are many more different types. This is a thermal explosion-proof detector and many others. Which one to choose for a particular room depends on various factors, which will be discussed below.

What to focus on when choosing?

Each thermal sensor has certain classification characteristics. They are usually reflected in technical documentation. We list those that you should pay attention to:

1. Response temperature
2. Operating principle
3. Design features
4. Inertia
5. Type of control zone

For example, for large premises, it is recommended to install thermal fire detectors with a linear detection zone. When choosing a device, be sure to pay attention to the response temperature; it should not differ from the average by more than 20 ° C. Sudden changes in the control zone are unacceptable, they can lead to false alarms

Is it possible to use sensors everywhere?

There is a list of documents regulating the use of fire fighting equipment. They indicate that heat detectors are acceptable for use in most industrial and residential facilities. But at the same time, there is a list of premises where their work is impractical:

• computing centers
• rooms with suspended ceilings

Ensuring the functionality of the control panel in a two-threshold mode with the formation of signals “Fire 1”, “Fire 2” for one and two detectors is currently being actively discussed in the industry press and in specialized forums. Coordination problems were initially determined by the lack of information in the documentation about the parameters of the control panel alarm loop modes. According to clause 7.2.1.5 GOST R 53325 – 2009 “Fire fighting equipment. Technical means. Fire automatics. General technical requirements. Test methods" in the technical documentation for control panels must indicate "the current ranges in the non-addressable alarm loop, including the maximum supply current of the detectors, at which the control panel registers all provided types of notifications and the range of supply voltages"

Problems of coordinating IP with PPKP

Currently, control panel manufacturers indicate loop thresholds in the form of its resistance, which can be used in practice only when connecting passive contact fire detectors with additional resistors. When using active fire detectors, this information is of little use, since due to the nonlinear current-voltage characteristic, their internal resistance changes significantly at different loop voltages. In turn, the voltage of the loop depends on its load, that is, on the resistance of the detectors in the “Fire” mode. Thus, the determination of the values ​​of additional resistors is carried out experimentally using two samples of detectors and one sample of the control panel without taking into account the spread of their parameters from sample to sample, and even more so during operation.

As a carbon copy, the technical specifications for DIPs indicate that “the output signal of the detector is generated by reducing the internal resistance to a value of no more than 500 Ohms at a current through the detector of 20 mA.” The words “no more” mean that the typical resistance value can differ significantly from 500 Ohms, and taking into account the fact that quite a lot of devices have a short circuit current of the order of 20 mA, they completely lose their meaning. This characteristic in the DIP passports has been preserved since the times of single-threshold alternating loops with a permissible detector supply current in standby mode of 8–10 mA, and in the “Fire” mode, when the fire detector was activated, it was only necessary to increase the current by a significant amount. To ensure that when several smoke detectors are activated, a condition close to a loop short circuit does not occur, the detectors have since used zener diodes, which do not allow the loop voltage to decrease below the stabilization voltage, regardless of the number of activated detectors in the loop.

To operate the loop in a two-threshold mode, it is necessary to ensure stable characteristics of the control panel and the detector, which currently no one guarantees. Typically used additional resistors and an end-of-line resistor with 5% tolerances may not provide reliable generation of the “Fire 1” signals when one detector is activated and “Fire 2” when two detectors are activated. The loop parameters in the “Fire 1” and “Fire 2” modes may overlap. And in the so-called combined loop, designed for the simultaneous connection of normally closed heat and smoke detectors, that is, in fact, already in a four-threshold loop, when the loop breaks, due to the current consumption of the smoke detectors, the signals “Fire 1” and “Fire 2” are generated, as when triggered heat detectors. More reliable recognition of the activation of one or two detectors in a loop is ensured by using the control panel with adaptive thresholds “Fire 1”, “Fire 2”, the value of which is programmed in accordance with the current consumption of fire detectors in standby mode. Obviously, companies that produce both detectors and fire alarm control systems have significantly greater opportunities to work out the issues of matching detectors with fire appliances.

Requirement for "Fire" mode indication

The requirements for coordination of the control panel with non-addressed fire detectors are set out in general terms: clause 4.2.1.1 of GOST R 53325-2009 states that “fire detectors interacting with the fire alarm control panel must ensure information and electrical compatibility with it,” and clause 4.2.1.3 contains the requirement: “The electrical characteristics of fire detectors (voltage and currents of the standby mode and the alarm mode) must be established in the technical documentation (TD) for fire detectors of specific types and must correspond to the electrical characteristics of the fire alarm loop of the fire receiver control device with which fire detectors are supposed to be used.” It is not possible to consider the problems of compatibility of the entire variety of fire detectors within the framework of one article, as a result of which we will limit ourselves to thermal contact fire detectors.

The documentation of any control panel provides connection diagrams for heat detectors with normally closed and normally open contacts and the values ​​of ballast and additional resistors, respectively, for operation in two-threshold (four-threshold) mode. If there are no smoke detectors in the same loop, it seems that no problems should arise. However, many manufacturers of control panels do not seem to be aware that since 01/01/2001, thermal detectors that do not consume electric current are subject to the requirement of clause 17.6.1 NPB 76-98 “Fire detectors. General technical requirements. Test methods" that "PIs must contain a built-in red optical indicator that turns on in the alarm transmission mode. If it is impossible to install an optical indicator in the PI, the latter must provide the ability to connect an external optical indicator or have other means for local indication of the alarm transmission mode.” Clause 4.2.5.1 of the currently valid GOST R 53325-2009 states: “Fire detectors must contain a built-in optical indicator that flashes in standby mode and turns on in a constant light mode when an alarm message is transmitted. If it is impossible to install an optical indicator in the fire detector, the latter must provide the ability to connect an external optical indicator or have other means for local indication of the standby mode and the alarm transmission mode" with the note: "The requirement for the presence of an optical indicator for IPT class above B and for detectors intended for work in hazardous areas, is recommended. The requirement for the indicator to flash in standby mode for non-addressable detectors is recommended. The requirement for the indicator to flash in standby mode for addressable detectors applies to detectors manufactured after 01/01/2010.”

Accordingly, heat detectors with a built-in LED indicator (Fig. 1) and detectors without an indicator, to which external indicators are connected, are currently produced. Therefore, when determining the values ​​of additional resistors, it is necessary to take into account the presence and electrical characteristics of the connected LEDs.

Rice. 1. Heat detector with built-in indicator

LED characteristics

An LED, like any other diode, has a nonlinear current-voltage characteristic, that is, unlike a resistor, its resistance varies widely depending on the current. As an example in Fig. Figure 2 shows the current-voltage characteristic of the indicator LED from the fire detector. When the LED current changes in the range from 1 to 20 mA, the voltage on it is approximately equal to 2 V, or more precisely, at 1 mA the voltage is 1.84 V, and at 20 mA - 2.23 V. Accordingly, the resistance of the LED at a current of 1 mA is 1 .84 kOhm, and when the current increases to 20 mA, its resistance drops to 111.5 Ohm! Therefore, the specifications for LEDs usually indicate the typical and maximum voltage drop across the LED. These values ​​​​show the possible variation in LED parameters: for example, a typical voltage drop across an LED may be indicated as 2.2 V at 20 mA, and a maximum of 2.6 V.

Rice. 2. Current-voltage characteristic of the indicator LED

The brightness of LEDs is also usually indicated at a current of 20 mA and, depending on the type of LED, can be at least 5-10 mcd and reach about 2000-3000 mcd, which significantly affects their price. In a fire loop, it is not possible to provide an indicator current of about 20 mA, since even the short-circuit current of the loop for many devices does not reach this value. Of course, to provide an indication function, the LED must have sufficient brightness and a wide radiation pattern when turned on. According to expert assessment, standard LEDs provide more or less acceptable brightness at currents of at least 5 mA, and super-bright LEDs at currents from 1.5 mA. It should be noted that to simplify installation in heat detectors, it is advisable to use non-polar LED indicators.

Connection diagram for heat detectors

Heat detectors with normally closed contacts are connected to the fire alarm loop in the same way as smoke detectors, and the difference lies mainly in the significantly lower voltage drop in the active mode and the absence of current consumption in the standby mode. Accordingly, approximately the same problems are present when matching a loop in a two-threshold mode, the degree of significance of which mainly depends on the type of device used. In this article, we will limit ourselves to considering the problems that arise when using heat detectors with normally closed contracts, which are respectively connected in a loop in series.

Rice. 3. Connection diagram for heat detectors without indicator

The principle of operation of the so-called thermal loop is to increase the resistance of the loop by the amount of ballast resistance connected in parallel to the detector when it is activated (Fig. 3). Without taking into account the cable resistance, the resistance of the detector contacts and the leakage current, the resistance of the loop in standby mode is equal to Rok, when one detector is activated: RШС = RBAL + RОК, when two detectors are activated: RШС = 2RBAL + RОК, three detectors: RШС = 3RBAL + RОК and etc. And if we consider a “thermal” loop with detectors without indicators, then significant problems should not arise. The documentation for any device indicates the values ​​of terminal and ballast resistors. In addition, loop resistance ranges in various modes are usually given. For example, if the value of the ballast resistors is 4.7 kOhm each, and the terminal resistor is 7.5 kOhm, then when the first detector is triggered, the resistance of the loop increases to 12.2 kOhm, and when two detectors are triggered - to 16.9 kOhm, and with resistance loop more than 20 kOhm, it would be possible to detect a break in the loop and generate a “Fault” signal. However, it must be taken into account that when the device operates in two-threshold mode, at least three fire detectors must be installed in the room. Consequently, there is a certain probability of simultaneous activation of the 2nd and 3rd detectors, its value depends on many factors, for example, on the location of the detectors relative to the source and the identity of their characteristics, on the time characteristics of the device, that is, how close in time the detectors are triggered by it it identifies . But in any case, the magnitude of this probability is not zero. But in devices with re-querying the status of detectors, including thermal ones for some reason, this probability is close to one if all three detectors are in working order. Thus, taking into account the high rate of development of an open source, if after the first heat detector is triggered, the device automatically resets the loop and repeats the status of the loop in about half a minute, then by this time all three detectors will have time to activate. In this case, the loop resistance will be equal to 21.6 kOhm, and when four detectors are activated - already 26.3 kOhm. Therefore, to exclude the formation of a “Fault” signal in the event of a fire, the threshold of this signal should be selected at about 30 kOhm and the re-request mode should be excluded.

In passing, we note that the loop break threshold at the level of 30 kOhm excludes the possibility of working with smoke detectors. When the loop voltage at idle is about 20 V, the threshold of the “Fault” signal corresponds to a loop current equal to 0.67 mA, and minus the leakage current of 0.4 mA from a resistance of 50 kOhm, which must be ensured according to the requirements of GOST R 53325— 2009, less than 0.27 mA remains to power the detectors in standby mode. This limits the protection capabilities of such a loop to one room with three smoke detectors. When trying to protect even two rooms, that is, when six smoke detectors with a current of 0.1 mA are connected to the loop, their total current in standby mode will be equal to 0.6 mA, and if the loop breaks between two rooms, or when the detectors are removed during in the second room, a break in the loop will not be detected, since the current of the remaining three detectors, equal to 0.3 mA, exceeds the threshold for generating the “Fault” signal.

In addition, the formation of a so-called “combined” loop with the simultaneous activation of smoke and heat detectors, even with normally open contacts, cannot be allowed, based on tactical considerations. The level of protection with smoke and heat detectors differs significantly; accordingly, there should be a different reaction to the activation of a heat detector in the presence of an open fire compared to the detection of smoldering fires by smoke detectors. On the other hand, the standards define the protection of most objects with smoke detectors as providing early fire detection and protecting human lives. Heat detectors are currently used quite rarely and, as a rule, in areas where the use of smoke detectors is not allowed due to operating conditions. It is quite advisable to protect these zones with separate loops to ensure targeting, taking into account the detection of a fire at the stage of an open fire.

Calculation of a loop with heat detectors with an indicator

Calculation of the loop when using heat detectors with indicators (Fig. 4), according to the requirements of the standards that have been in force for 10 years, naturally becomes more complicated. In addition, if the documentation for the control panel contains diagrams for switching on heat detectors similar to those shown in Fig. 3, then questions arise: what value of ballast resistors should be selected in the presence of LEDs, is it possible to meet the established thresholds of the “Fire 1”, “Fire 2” signals, taking into account the nonlinearity of the characteristics of the LEDs, will they indicate anything, etc. . Of course, for an accurate calculation, more complete characteristics of the control panel are required, which are not indicated in the documentation, based on which we will try to determine general patterns for various classes of devices.

Rice. 4. Connection diagram for heat detectors with indicator

From the previous calculation, with an unloaded loop voltage of 20 V and an output resistance of the device loop of 1 kOhm and with a loop resistance in the “Fire 1” mode of 4.7 k + 7.5 k, the current is approximately 1.515 mA. Let us determine the value of the ballast resistance assuming a voltage drop across the LED equal to 2 V (Fig. 2). With a loop current of 1.515 mA across a 4.7 kOhm resistor, it drops to 1.515 x 4.7 = 7.12 V. Minus the 2 V that drops on the LED to the ballast resistance, 5.12 V remains, and taking into account the loop current of 1.515 mA, its value is should be 3.38 kOhm. We will not round this value to the nearest resistor value in order to assess how much the parameters of the loop differ when the second and third heat detectors with an indicator are triggered from those without an indicator. Check: the resistance of the LED with a voltage drop across it of 2 V and a current of 1.515 mA is equal to 2/1.515 = 1.32 kOhm, which, together with the calculated ballast resistance, amounts to the required 4.7 kOhm.

When the second detector is activated, the loop current will be determined as the quotient of dividing the total voltage drop across the resistors by their total value. That is, from the initial loop voltage of 20 V, we subtract the voltage drop across the two LEDs - approximately 4 V. We get 16 V - drop across the resistors, their total value is 1 k + 3.38 k + 3.38 k + 7.5 k = 15.26 k, and the current is correspondingly equal to 1.05 mA. The total resistance of the circuit is 20V/1.05mA = 19.05 kOhm, and by subtracting the output resistance of the device 1 kOhm, we get a loop resistance of 18.05 kOhm. We obtained a slightly larger value compared to 16.9 kOhm when using heat detectors without indicators. Similarly, you can calculate the parameters of the loop when three detectors are activated, however, it should be noted that reducing the current value to 1 mA makes it problematic to control the indication of two detectors even when using ultra-bright LEDs, moreover, at currents less than 1-1.5 mA, the current-voltage characteristic “bends” and it is necessary to take into account the change in voltage drop across the LED (Fig. 2). It’s easier to say that devices with a unipolar cable are not designed to connect heat detectors with indicators, so their connection is not given in the documentation. However, there are more significant nuances than the lack of indication of the “Fire” mode when using a remote indicator!

Remote indicator or fault redundancy?

According to regulatory requirements in force since 2003, in order to reduce the likelihood of generating a false “Fire” signal, most fire protection systems are triggered when at least two detectors are triggered and there is a third backup detector in a two-threshold loop. The “two out of three” operating logic is implemented, that is, the “Fire 2” signal is generated when any two detectors are activated, and the third detector may be faulty. This algorithm is not provided when detectors with normally closed contacts and a remote indicator are included in the “thermal” loop. If the circuit of the remote indicator or ballast resistor is broken when the heat detector is triggered, the loop breaks (Fig. 5) and the device generates a “Fault” signal. Naturally, when the remaining serviceable detectors are triggered, the loop break is not eliminated and the fire is not detected. Moreover, in standby mode, with the detector contacts closed, this malfunction is not detected.

Rice. 5. A break in the remote indicator circuit causes a break in the loop in case of fire

In addition, even if a serviceable detector is triggered first, and a detector with a broken remote indicator circuit is the second, the device will first generate a “Fire 1” signal, and when the second detector is triggered, it will detect a break in the loop and generate a “Fault” signal according to the logic of the operation of most domestic devices. Thus, the operating logic of the system, as defined in the regulations, is grossly violated - instead of backing up faulty detectors, the fault itself is backed up. If one of two triggered detectors has a break in the remote indicator, the “Fire” signal is blocked.

In devices with a re-request function, when all three detectors are triggered by the time the loop is rechecked, the fault reservation logic will work to the maximum, using “OR”: if at least one of the three detectors has an open circuit of the remote indicator, then the “Fire” signal is blocked from - for a cable break.

To ensure the operability of the system, foreign standards contain a general requirement that applies to all fire detectors, that a break or short circuit in the circuits of remote indicators and other additional devices should not impair the functionality of the detector.

Thus, when using heat detectors with normally closed contacts, it is necessary to work out issues of coordination with the control panel in advance to avoid significant difficulties at the stage of installation and acceptance testing.

I.G. Not bad
Technical Director of the Center-SB business group, Ph.D.

Maximum thermal fire detector IP 103-10. Connecting device US-4 PASHK.425212.050

R1* - resistor C2-33N-0.25-5.6 kOhm±5%;
R2, R3 - resistor S2-33N-0.25-1 kOhm±5% when using energy-consuming detectors IP103-10-(A1), IP103-10-(A3);
IP1, IP 2 - energy-consuming fire detectors IP103-10-(A1), IP103-10-(A3).

*When using energy-consuming detectors (IP103-10 up to 40 pcs., etc.), the value of the terminal resistor R1 must be increased so that the total resistance of the detectors and the terminal resistor is 5.6 kOhm ± 10%, for this you can connect to the terminals AL nominal resistor (5.6 kOhm) and measure the voltage on it (voltage on AL in nominal mode is from 17 to 20 V); then disconnect the resistor and connect detectors to the AL terminals (they must be in the “Normal” mode) and select the value of the terminal resistor so that the voltage at the AL terminals coincides with the voltage measured at the nominal resistor. When using detectors with other control and control devices, you should use the descriptions for these devices.

2.2. Detector installation

Figure 2 shows the overall and connecting dimensions of the detector and connecting device. Placement and installation at the controlled facility must be carried out in accordance with the requirements of NPB 88-2001 “Fire extinguishing and alarm installations. Design standards and rules" and RD 78.145-93 "Systems and complexes of fire and security fire alarms. Rules for production and acceptance of work."

2.3. Checking the functionality of the detector

2.3.1. For the duration of the tests, it is necessary to turn off the outputs of control panels and actuators that control automatic fire extinguishing equipment (AFS) and notify the relevant organizations.

2.3.2. Turn on the power supply to the control panel and observe single flashings of the LED of the remote indicator, which means indicating the detector's standby mode.

2.3.3. Turn on the fan heater and direct the heat flow to the sensitive element of the detector.

2.3.4. Observe the transition of the detector indicator to the constant light mode and the transition of the control panel alarm loop to the FIRE mode, while the single blinking of the LED of the IVS-2 remote indicator stops.

2.3.5. After the tests, make sure that the detectors are ready for normal operation, restore connections between the control panels and actuators with ASPT means and notify the relevant organization that the system is ready for normal operation.

Thermal fire detector IP 101-29-PR is designed to detect fires accompanied by an increase in temperature inside the controlled space in enclosed spaces of various buildings, structures and transmit the "Fire" signal to the addressable control panel "RUBEZH-2A", "RUBEZH-2AM" , PPKPU 011249-2-1, “RUBEZH-2OP”, “RUBEZH-4A”. Power supply and information exchange of the detector are carried out via a two-wire communication line. The detector has two ways to detect fires: by maximum temperature and by the rate of temperature rise. The detector does not respond to changes in humidity, the presence of flame, natural or artificial lighting.

According to the operating principle addressable thermal fire detectors IP 101-29-PR are maximum-differential detectors that can identify a fire not only by the ambient temperature, but also by the rate of increase in its temperature. As a sensitive element, a heat fire detector uses a thermistor - a resistor whose resistance changes depending on the temperature. The advantage of the thermistor over other temperature sensors is its high temperature sensitivity, as well as high resistance, which eliminates the problems associated with the need to amplify the signal.
Based on comparison the current ambient temperature with the results of previous measurements, addressable thermal fire detectors determine the rate of temperature change. When the current temperature and its growth rate exceed the set threshold value, the control panel issues a fire alarm. This helps to avoid false alarms of the detector when the temperature changes quickly in normal situations, for example, when opening the front door or turning on heating appliances.

Thermal maximum differential addressable analog (temp. 54-85C) detector IP 101-29-PR performs the following functions:

• ambient temperature measurement;
• calculation of the rate of temperature change;
• processing measurement results using special algorithms and making decisions on generating the “Fire” signal;
• indication of the detector operating mode.

The addressable detector is direct temperature measurement device. Information processing is carried out by a built-in microcontroller.
The detector consists from a socket and a sensor, which is a plastic case, inside of which there is a board with radio elements that provides signal processing based on a microcontroller.
Sensor plug connection with socket provides ease of installation, installation and maintenance of the detector.
Temperature measurement is carried out microcontroller on command from the control panel. The rate of temperature change is calculated by the microcontroller. If the specified values ​​for any parameter are exceeded, a “Fire” signal is generated.
For status information The detector is equipped with an optical indicator. The indication modes are shown in the table.

State	Indication
Standby mode	Single flash with repetition period 5 s
Fire mode	Flashing at 2 Hz

The "Fire" signal remains after the detector has been exposed to temperature factors. The signal is reset from the control panel.

• It is possible to view the ambient temperature through the Rubezh control panel
• Power supply and communication of the detector IP 101-29-PR carried out via a 2-wire address bus with any number of branches.
• Detector testing IP 101-29-PR possible using a button or a special remote laser pointer OT-1.
• The response time of the detector when the temperature rises from plus 25 °C is within the limits specified in Table 2, at any position of the detector to the direction of the air flow.

Basic technical data and characteristics

Diagram for connecting detectors to two-wire loops.

Requirements NPB 88-2001*	Characteristics and functions of IP 101-29-PR detectors
a) the area of ​​the room is not more than the area protected by the fire detector specified in the technical documentation for it, and not more than the average area indicated in tables 5, 8 given by the NPB	Heat detector IP 101-29-PR provides protection for a room with an area of ​​25 m2 (with a height of the protected room up to 3.5 m)
b) automatic monitoring of the functionality of the fire detector is provided, confirming the performance of its functions with the issuance of a malfunction notification to the control panel (PKP)	Automatically controlled: presence of a detector, presence of two detectors with the same addresses, short circuit of the loop
c) identification of a faulty control panel detector is ensured	If a malfunction is detected, the address of the faulty detector is displayed on the display of the Rubezh gearbox with an indication of the type of malfunction
d) the signal from the fire detector does not generate a signal to start the control equipment that turns on automatic fire extinguishing or smoke removal systems or fire warning systems of the 5th type according to NPB 104	The Rubezh control panel generates ATTENTION and FIRE signals when one or two addressable detectors are triggered IP 101-29-PR in the train.

It is impossible to be prepared for a fire; it is always sudden and uncontrollable. But it is possible to minimize the risk of its occurrence by significantly reducing predictable material damage. For this purpose, experts have invented fire detectors, which are currently the only means capable of detecting a fire without a person. One of these is a thermal fire sensor or detector, briefly TPI.

The name itself - thermal - explains the principle of operation of the device. It contains one or more transducers - sensitive elements, which, sensing a temperature increase in the environment, lead to the activation of a loud identification signal through an audible alarm.

There is another type of detector - a fire smoke detector. It triggers on aerosol combustion products, in other words, smoke, or more precisely, its color. The advantage of fire-fighting smoke detectors is that it is allowed in administrative buildings, unlike a heat detector, but the disadvantage is that it will wake everyone up not because of a fire, but, for example, a large accumulation of dust or steam. Moreover, strictly speaking, calling it a sensor is incorrect, because it is only an integral part of the detector.

Main types

Based on the type of the main component of the TPI - the sensitive element or controller, there are four main types:

• Contact TPI. When the temperature changes, the installed contact or electrical circuit opens, a special cable breaks and causes an audible signal. The simplest, usually domestic models, are a closed contact of two conductors, packaged in a plastic container. More complex ones have a temperature-sensitive semiconductor with negative resistance. If the ambient temperature increases, the resistance will drop and a controlled current will flow through the circuit. As soon as it reaches a certain point, the alarm will go off.
• IN electronic sensor sensors are installed that are located inside the cable; as soon as the temperature reaches a certain threshold, the resistance of the electric current in the cable changes, which is transmitted to the control of the control device. Highly sensitive. The principle of the device is quite complex.
• Optical detector works on the basis of fiber optic cable. As the temperature increases, the optical conductivity changes, which leads to an audible warning.
• A metal tube with gas, hermetically filled, is necessary for mechanical TPI. The effect of temperature on any part of the tube will lead to a change in its internal pressure and trigger a signal. Deprecated.
• Other types. Semiconductor ones have a special coating with a negative temperature coefficient, electromechanical ones consist of wires under mechanical tension, coated with a heat-sensitive substance.

Types of fire detectors

Firefighters respond to different parameters of fire spread. Hence the classification into types.

The absolute value threshold is set in the maximum fire sensor:

• pressure,
• temperature - as soon as the environmental indicator reaches it, people will be notified.

Domestic devices with an operating temperature of 70-72 degrees are produced en masse. They are also very popular due to their financial accessibility.

For a differential fire alarm sensor, the rate of change of the sign that it monitors is important.

Such devices are recognized as more effective than maximum TPI -

• give the alarm earlier
• They are stable in operation, but due to two elements installed at a distance, they are higher in price.

Maximum differential devices combine both parameters.

When planning to purchase this type of fire-fighting devices, keep in mind that their temperature threshold must be at least 20 degrees higher than the permissible temperature at the facility.

Thus, technical specialists divide modern fire alarm systems into discrete (based on threshold) - they are discussed above - and analog. Analog thermal fire sensors, in turn, are divided into non-addressable and addressable. The latter transmit not only information about the fire, but also their address code.

Both discrete and analog measure the characteristics of fire factors; the fundamental difference is in the method of signal processing.

For analogues it is more complicated and its essence lies in special systematic algorithms.

• Analog Addressable Thermal Devices regularly collect information about the condition of the premises. They can produce the data they are programmed to collect in real time.
• Explosion-proof thermal fire detectors are needed where the risk of fire is high and explosive substances may be present in the air. They seem to be armored, as they are located on various power units, oil pipelines, etc. They differ in the degree of protection, the number of sensors and different set temperature thresholds.
• U linear heat detectors a cable with a heat-sensitive polymer is used - a thermal cable - it records any changes along its entire length as a single fire sensor. Used where the ceiling is large, such as an indoor stadium. In addition to the ceiling, you can also mount it on the walls.
• Multipoint thermal devices opposed to inherently linear. They are part of a single system that controls several zones and is combined into an electrical circuit. Signals received from fire sensors are processed in a single unit.

Operation and Installation

The connection diagram for thermal sensors is given in the operating instructions, however, difficulties may arise.

The requirements of GOST R 53325-2009, paragraph 4.2.5.1, require thermal detectors to be equipped with a built-in or remote optical indicator.

When calculating the values ​​of additional resistors, take into account the electrical components of the connected LED indicators.

Look in the device passport for the typical and maximum voltage drop, which indicate the limit of the parameters. For ease of installation, it is better to use LED non-polar indicators.

Normally closed contacts of thermal devices are connected to the loop in the same way as for smoke devices. The difference is that in the standby state, thermal sensors do not consume electric current, and in active mode it is less than that of smoke sensors.

Fire alarm thermal sensors have the following resistances in the connection diagram:

• Rbal.,
• Rok.,
• Radd.

We study the operating instructions for the monitoring device and take into account the resistor values.

Rbal. similar to Radd., but it is not included in the control device kit; you will have to buy it additionally.

In normal mode, the sensors are short-circuited, which means that resistance Rbal will appear only if one or two of the devices operate. And then an “Alarm” signal can be generated.

For controllers “ Mirage” there is the following diagram. If one is triggered, the “Attention” signal will be received, if the second one is triggered, the “Fire” command will follow.

The designation of the heat detector in the diagram, as well as other components, is as follows:

• Shs– alarm loop,
• IP— thermal fire detector,
• YPRES– manual fire detector,
• DIP– fire smoke detector.

Conventional graphic designation of an automatic heat detector according to the requirements of regulatory documentation - .

Standards and features of installation/connection of thermal sensors are regulated by water rules of fire protection systems 5.13.130.2009 with the latest amendments from 06/20/2011.

From Table 13.5, the distance between the thermal point devices, as well as between them and the wall, becomes known (do not forget about the exceptions specified in paragraph 13.3.7).

Source: SP5.13.130.2009.

It is not difficult to guess that the area covered by the sensor depends on the height of the room. At the same time, many install two devices in each room in case one sensor fails to work.

The distance from one to another should be limited to half the recommended one. But this works with point non-addressable sensors. Addressable analogue ones do not need duplication, since they have a completely different operating principle.

• When placing sensors in rooms, it is necessary to take into account the characteristics of the distribution of combustion products in them.
• It is ineffective to install heat sensors in “dead” zones, where hot air is the last to reach, and the fire protection device will work too late.
• So, when laying the thermal cable of a linear heat detector, there is no need to do this 15-20 cm from the corners along the ceiling and walls.
• Don’t forget about hoods and air conditioners - place the device at least a meter away from them.

Physical laws give rise to the principles that underlie the installation of fire detectors:

• a flat ceiling is protected along a circle lying in a horizontal surface;
• you need to take into account the distance from the floors of the room.

Malfunctions and ways to eliminate them

First of all, we read about them in the operating manual in a specially dedicated section. The description indicates what may not work and what method will help fix the problem.

The classic reasons are unprofessional installation and manufacturing defects. A detected defect leads to a warranty period, which averages from 18 to 36 months, but sometimes 12 months.

• Experienced engineers also point out a false fire alarm in the case of repairs, when dust gets into the device and it goes off.
• Sometimes insects also cause unjustified anxiety. Rubbing with alcohol and blowing helps.
• The loops can periodically notify of a fire when the wires are twisted and the contact is unstable.
• Electromagnetic interference from devices has also not been canceled, so they must be taken into account. Seasonal changes, acoustic vibrations and aggressive environments also influence malfunctions.
• False alarms often do not indicate high sensitivity of detectors, but low quality. Experts also warn that all cheap developments lose sensitivity over time. And only replacement will help here.

To solve most problems due to a malfunction, checking the connections, the correct location of the detectors and the normal operation of the contact connections will help.

Also, high-quality detector components will help prevent undetected fire.

Manufacturers and popular models

Fire detectors are produced by Russian and foreign manufacturers. Among them

• oldest Japanese company Hochiki,
• most popular Siemens, into which the Swiss manufacturer Cerberus joined.
• The fire detectors of the British company have proven themselves well Appolo.
• Also well known System Sensor, whose products are manufactured in 8 largest countries - from the USA to Russia.

In our country it specializes in fire heat detectors

• company “Argus-Spectrum”, located on the basis of the scientific and industrial complex in St. Petersburg.
• Komplektstroyservis is one of the leaders in domestic developments.
• Magneto-Contact produces sensors based on sealed contacts,
• wide range of products from “ Siberian Arsenal”,
• research and production enterprise “ Special Informatics-SI”.
• Private enterprise also offers its products “ Arton" And " Special automation”.

Prices

The simplest maximum fire-fighting heating devices are domestic, their price ranges from 40 to 150 rubles.

• Additional options, for example, memory for a triggered device, a light and/or remote indicator, an increase in their number entails a doubling in price, range from 270 rubles. and up to 600.
• Maximum differential sensors can be purchased for a price starting from 500 rubles. up to 900.
• One of the best selling models Aurora TN (IP 101-78-A1), its price is on average 700 rubles.
• The most popular model of explosion-proof detector due to its affordability IP 101-3A-A3R will cost 200 rubles on average, although most stores offer explosion-proof devices from 800 to 1,000 rubles.

Foreign addressable maximum differential devices

• cost from 1000 rubles per piece and higher.
• Among the addressable analog maximum differential ones - best selling model S2000 IP-03, She is standing from 500 to 800 rubles, and in general the range of addressable detectors reaches 2,000 and even higher.
• thermal sensors - thermal cables - depending on the characteristics (cable resistance, maximum permissible length, current voltage, etc.) are sold on average from 300 to 700 rubles.

Conclusion

Information about the principles of operation, design features, types and types of heat fire detectors will help you choose the most suitable model carefully and without unnecessary financial costs. Installation rules and regulations are not that complicated, and if you treat them responsibly, you can prevent many malfunctions. It is best to carry out installation under the strict guidance of experienced electricians.

Return