Fire alarm types. Burglar alarm stub Fire alarm stub what

Fire alarm (PS) is a set of technical means, the purpose of which is to detect a fire, smoke or fire and notify a person in a timely manner. Its main task is to save people's lives, minimize the damage caused and preserve property.

It may consist of the following elements:

• Fire control panel (PPKP)- the brain of the entire system, controls the loops and sensors, turns on and off automation (fire extinguishing, smoke removal), controls annunciators and transmits signals to the control panel of a security company or a local dispatcher (for example, a security guard);
• Various types of sensors, which can respond to factors such as smoke, open flames and heat;
• Fire alarm loop (SHS)- this is a communication line between sensors (detectors) and the control panel. It also supplies power to the sensors;
• Annunciator- a device designed to attract attention, there are light - strobe lamps, and sound - sirens.

According to the method of control over the loops, fire alarms are divided into the following types:

PS threshold system

It is also often referred to as traditional. Principle of operation of this type is based on the change in resistance in the loop of fire alarm systems. Sensors can only be in two physical states "norm" and "fire". If the fire factor is fixed, the sensor changes its internal resistance and the control panel issues an alarm signal on the loop in which this sensor is installed. It is not always possible to visually determine the place of drawdown, because. in threshold systems, an average of 10-20 fire detectors are installed on one loop.

To determine the malfunction of the loop (and not the state of the sensors), an end-of-line resistor is used. It is always installed at the end of the loop. When using fire tactics "PS triggering by two detectors", to receive a signal "Attention" or "probability of fire" additional resistance is installed in each sensor. This allows you to apply automatic systems fire extinguishing at the facility and the elimination of possible false alarms and damage to property. Automatic fire extinguishing starts only in case of simultaneous operation of two or more detectors.

PPKP “Granit-5”

The following FACPs can be attributed to the threshold type:

• series "Nota", manufacturer Argus-Spectrum
• VERS-PK, manufacturer VERS
• devices of the "Granit" series, manufacturer NPO "Siberian Arsenal"
• Signal-20P, Signal-20M, S2000-4, manufacturer NPB Bolid and other fire appliances.

The advantages of traditional systems include ease of installation and low cost of equipment. The most significant drawbacks are the inconvenience of maintaining a fire alarm and a high probability of false alarms (resistance can vary from many factors, sensors cannot transmit information about dust content), which can only be reduced by using a different type of fire alarm system and equipment.

Address-threshold system PS

A more advanced system is able to automatically periodically check the status of the sensors. Unlike threshold signaling, the principle of operation lies in a different algorithm for polling sensors. Each detector has its own unique address, which allows the control panel to distinguish them and understand the specific cause and location of the malfunction.

The Code of Rules SP5.13130 ​​allows the installation of only one addressable detector, provided that:

• The PS does not control fire alarm and fire extinguishing installations or type 5 fire warning systems, or other equipment that, as a result of launch, may lead to material losses and reduce the safety of people;
• the area of ​​the room where the fire detector is installed more area for which this type of sensor is designed (you can check it according to the passport technical documentation on him);
• the sensor performance is monitored and in the event of a malfunction, a “fault” signal is generated;
• It provides the possibility of replacing a faulty detector, as well as its detection by external indication.

Sensors in the address-threshold signaling may already be in several physical states - "norm", "fire", "fault", "Attention", "dustiness" and others. In this case, the sensor automatically switches to another state, which allows you to determine the location of a malfunction or fire with an accuracy of the detector.

PPKP "Dozor-1M"

The following control panels can be attributed to the addressable-threshold type of fire alarm:

• Signal-10, manufacturer of airbag Bolid;
• Signal-99, manufacturer PromService-99;
• Dozor-1M, manufacturer Nita, and other fire appliances.

Address-analogue system PS

The most advanced type of fire alarm to date. It has the same functionality as the address-threshold systems, but differs in the way the signals from the sensors are processed. The decision to switch to "fire" or any other state, it is the control panel that takes it, and not the detector. This allows you to customize the operation of the fire alarm according to external factors. The control panel simultaneously monitors the status of parameters installed devices and analyzes the obtained values, which can significantly reduce the likelihood of false alarms.

In addition, such systems have an undeniable advantage - the ability to use any address line topology - tire, ring and star. For example, in the event of a break in the ring line, it will split into two independent wire loops, which will fully retain their performance. In star lines, special insulators can be used. short circuit, which will determine the location of the line break or its closure.

Such systems are very convenient in maintenance, because. you can identify in real time the detectors that need to be purged or replaced.

The following control panels can be attributed to the analog addressable type of fire alarm:

• Two-wire communication line controller S2000-KDL, manufacturer NPB Bolid;
• A series of addressable devices "Rubezh", manufactured by Rubezh;
• RROP 2 and RROP-I (depending on the sensors used), manufacturer Argus-Spectrum;
• and many other devices and manufacturers.

Scheme of an addressable analog fire alarm system based on the S2000-KDL control panel

When choosing a system, designers take into account all requirements terms of reference the customer and pay attention to the reliability of operation, the cost of installation work and the requirements for routine maintenance. When the reliability criterion for a simpler system starts to drop, designers move on to using a higher level.

Radio channel options are used in cases where laying cables becomes economically unprofitable. But this option requires more money for maintenance and maintenance of devices in working order due to the periodic replacement of batteries.

Classification of fire alarm systems according to GOST R 53325–2012

Types and types of fire alarm systems, as well as their classification are presented in GOST R 53325–2012 “Fire fighting equipment. Technical means fire automatics. General technical requirements and test methods".

We have already considered address and non-address systems above. Here you can add that the first ones allow you to install non-address fire detectors through special expanders. Up to eight sensors can be connected to one address.

According to the type of information transmitted from the control panel to the sensors, they are divided into:

• analog;
• threshold;
• combined.

According to the total information capacity, i.e. the total number of connected devices and loops are divided into devices:

• small information capacity (up to 5 loops);
• medium information capacity (from 5 to 20 loops);
• large information capacity (more than 20 loops).

According to information content, otherwise, according to the possible number of issued notices (fire, malfunction, dustiness, etc.), they are divided into devices:

• low information content (up to 3 notifications);
• medium information content (from 3 to 5 notifications);
• high information content (from 3 to 5 notifications);

In addition to these parameters, systems are classified according to:

• Physical implementation of communication lines: radio channel, wire, combined and fiber optic;
• In terms of composition and functionality: without the use of computer technology, with the use of SVT and the possibility of its use;
• Control object. Management of various fire extinguishing installations, smoke removal facilities, warning and combined facilities;
• Expansion possibilities. Non-expandable or expandable, allowing mounting in a housing or separate connection of additional components.

Types of fire alarm systems

The main task of the warning and evacuation management system (SOUE) is the timely notification of people about a fire in order to ensure safety and prompt evacuation from smoky premises and buildings to a safe area. According to FZ-123 " Technical regulation about the requirements fire safety” and SP 3.13130.2009, it is divided into five types.

The first and second type of SOUE

For most small and medium-sized objects, according to fire safety standards, it is necessary to install the first and second type of notification.

At the same time, the first type is characterized by the mandatory presence of a sound annunciator - a siren. For the second type, more “exit” light displays are added. A fire alarm should be triggered simultaneously in all premises with permanent or temporary stay of people.

Third, fourth and fifth type of SOUE

These types belong to automated systems, the launch of an alert is fully automated, and the role of a person in managing the system is minimized.

For the third, fourth and fifth types of SOUE, the main method of notification is speech. Pre-designed and recorded texts are transmitted, which allow the evacuation to be carried out as efficiently as possible.

In the 3rd type additionally, “exit” light indicators are used and the order of notification is regulated - first for the service personnel, and then for all the rest according to a specially developed sequence.

In the 4th type there is a requirement to have a connection with the control room inside the warning zone, as well as additional light indicators for the direction of movement. Fifth type, includes everything listed in the first four, plus the requirement that there is a separation of the inclusion of light indicators for each evacuation zone is added, full automation of the management of the warning system and the organization of multiple evacuation routes from each warning zone is provided.

V.N. Korenev,
Ph.D., head of development
and implementation of Security Systems LLC,
Novosibirsk city

Threshold alarm loops, despite their low information content and susceptibility to interference, continue to be used in various systems alarm. This is due to the fact that there are still many conventional detectors and sensors on the market for alarm products that have two stable states at their output, corresponding to normal and alarm. They successfully compete with addressable products due to their low cost and compatibility with various control panels.

Despite the simplicity of circuitry, threshold signaling loops can be made much more informative than it is implemented in existing equipment. This becomes possible with the use of modern microprocessor technology, which increases the ADC capacity, data processing performance, built-in memory, and at the same time reduces the price.

However, the increase in information content is associated with the growth of controlled events and the complexity of the transition algorithms from one state to another. Describing these processes is becoming increasingly difficult. Therefore, when developing such products and describing them to users, it is convenient to use physical and software models of the signaling loop.

Each threshold alarm loop (AL) of the device can be described by models from two points of view:

From a physical point of view- This electrical circuit, connecting the device with detectors (sensors) through wired connections (Fig. 1). Each AL has different circuit options selected by the developer. The switching diagram shows the detector contacts, resistors and other components that ensure the operation of the loop.

Any detector can be represented as an electrical contact, which, when triggered, abruptly changes its resistance: it becomes either closed (contact resistance is equal to zero) or open (contact resistance is equal to infinity).

The detector contacts are connected by wire connecting lines to the terminals of the control panel.

In the control panel, the terminals are connected to the “Resistance Meter”, which measures the electrical resistance of the entire loop circuit, and the “Decider”, by the value of its resistance, decides whether the detector has worked or not.

Fig.1. Threshold alarm loop model

The AL is connected to the resistance meter through the terminals located on the board of the receiving and control device (RCD). The meter measures the electrical resistance of the entire loop circuit, and the deciding device, based on the value of its resistance, decides whether the detector has worked or not.

From an information point of view is a program object consisting of a fixed set of events. An event in the loop can occur as a result of a change in the resistance of the loop, or come from outside, in the form of control commands. The set of events is defined AL tactics. Each AL tactic includes:

1. Type of alarm loop (fire, security, emergency and control) and name;
2. Electrical wiring diagram;
3. AL resistance range scale, divided by thresholds;
4. Linking states to AL resistance ranges;
5. List of AL events;
6. event matrix.

As an example of the use of terms, consider the tactics of the fire alarm loop "Single Threshold". This tactic provides for the issuance of a “Fire” signal when any one or more detectors are triggered:

1. Alarm loop type - fireman, single threshold .
2. Wiring diagram - can be performed in several versions (Fig. 1.1.):

1. with normally closed detector contacts (K1, K2). In this case, the contacts are connected in series to the loop line, and the control resistors are connected in parallel to the detector contacts;
2. with normally open detector contacts (K3, K4). In this case, the detector contacts are connected in parallel to the loop line, and the control resistors are connected in series with the contacts;

Fig.2. Electrical circuits for switching on the contacts of fire detectors.

3) Scale of resistance ranges, divided by the developer by resistance thresholds into 8 ranges: D1 ... D8 (Fig. 3).

Fig.3. AL resistance range scale

When closing and opening the contacts of the detectors in various combinations, the resistance of the loop falls into one or another range.

1. Binding states to AL resistance ranges

Loop states are physical or logical properties that characterize the loop when its resistance changes.

In the "One-threshold" SPS, the following states are assigned by the developer:

• Norm;
• Fire;
• Break.

These states are bound to ranges:

1. AL Event List

An event is a transition from one state to another. In this case, both the states of the loop itself and other states of the device related to the loop are taken into account.

In the "One-threshold" SPS, the following events are assigned by the developer:

• Reset- an event in the device at the time of its reboot (power on);
• Not ready- an event meaning that after a reboot, the loop resistance is not in the "Normal" range;
• On duty- the loop resistance has moved into the "Normal" range [D5];
• Fire– loop resistance in any of the “Fire” ranges [D2] [D3] [D4] [D6] [D7];
• closure- loop resistance is in the "short circuit" range [D1];
• cliff- loop resistance is in the "Open" range [D8];

1. Event Matrix

The event matrix determines the sequence of occurrence of events when states change. Using the matrix, it is convenient to represent the loop operation algorithms. A matrix is ​​a table that contains the following elements:

Fig.4. Appearance event matrix.

The principle of applying the matrix to describe the loop operation algorithm is shown in Fig.5. As an example, in the far left column, we will select the current status as "On Duty". Let's highlight with a green background the line with events in the field of events that are possible while in this status. Next, consider what event will occur when a new state of the “Fire” loop appears:

Fig.5. An example of the operation of the matrix in the event of a "Fire" state

As a result of the matrix operation, the loop moved to the new current status "Fire". An analysis of the impact of new loop states in the "Fire" status shows that no other physical change in the loop resistance will change this status. In order to remove the loop from the “Fire” status, it must be transferred to the new “Reset” status. Such a state can come to the loop from the outside: for example, when the reset button is pressed.

Thus, the matrix representation greatly facilitates the description of complex algorithms for the operation of threshold alarm loops and can be used both in their development and in describing the operation of the product in the user manual. Obviously, the matrix representation is also convenient when describing the algorithms of other units of alarm products.

Literature:

1. Pinaev A., Nikolsky M. Assessment of the quality and reliability of conventional fire alarm devices // Journal "Safety Algorithm", No. 6, 2007.
2. Not bad I.G. Analysis of the loop parameters of a two-threshold control panel// Security Algorithms No. 5, 2010.
3. Device for monitoring dangerous situations and alerts "Keeper-IT"//

Loop (fire and security alarm) - wired and non-wired communication lines, laid from fire detectors to a junction box or control panel. :pp. 3.93, 3.118

Security and fire loops have different operation algorithms. The "malfunction" state is not provided for the security loop - in the event of a break, short circuit, short-term or insignificant change in the resistance of the loop, an "Alarm" signal is generated. This is quite justified due to the high probability of deliberate damage to the loop in order to disable security detectors.

Signaling (with the exception of local signaling) requires the use of communication lines or channels. Signaling can be done in several basic ways:

A set of alarm loops, connecting lines for transmission via communication channels or separate lines to the control panel, devices for connecting and branching cables and wires, underground sewers, pipes and fittings for laying cables and wires is included in the linear part of the alarm system.

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Remote signaling

Automatic fire extinguishing installations (with the exception of autonomous ones) must perform the function of a fire alarm. :P. 4.2 Pipelines filled with water, aqueous solution, compressed air or cable with thermal locks. :P. 3.64

Mechanical

The first fire alarm installations used mechanical loops. They were a load suspended on a rope that burned in a fire. At the same time, the load fell and, due to the energy of its fall, an alarm bell was activated. Such a device was patented in the middle of the 19th century in England. The design was further developed in the US in an 1886 patent. The design used several loops.

Before the advent of widely available electronic equipment, tethered devices continued to be widely used as inducement devices. The cables consisted of several links, the links of the cable were connected by fusible locks. Instead of fusible locks, it was possible to turn on manual start devices. The ends of each branch of the cable system were attached to the lever of the incentive valve of the fire extinguishing system and the cable tension device.

hydraulic

Pneumatic

Wired

Wired (telesignalization)

Fire alarm loops, as a rule, are carried out by communication wires, if the technical documentation for fire alarm control devices does not provide for the use of special types of wires or cables. For fire alarm loops, only cables with copper conductors with a diameter of at least 0.5 mm can be used. Automatic control of the integrity of the loop along the entire length is required.

With parallel open laying, the distance from fire alarm loops with voltage up to 60 V to power and lighting cables must be at least 0.5 m. It is possible to lay loops at a distance of less than 0.5 m from power and lighting cables, provided they are shielded from electromagnetic interference .

In rooms where electromagnetic fields and pickups are high, fire alarm loops must be protected from pickups.

At the end of the loop, it is recommended to provide a device that provides visual control of its on state, as well as junction box [remove template] to assess the condition of the fire alarm system, which must be installed at an accessible location and height. As such a device, a manual call point or a loop control device can be used.

According to the structure, the loops are divided into:

Unaddressed

Multi-wire telesignaling systems are improved remote signaling systems. To reduce the number of loops, several (two...four) values ​​of the impulse characteristic per one loop are used. The most common impulse features are polarity and magnitude. :72

Constant sign

The integrity of the constant-sign loop is controlled using a terminal device - a resistor installed at the end of the loop. The higher the value of the terminating resistor, the lower the current consumption in standby mode, respectively, the lower the capacity of the backup power source and the lower its cost. The state of the loop of the control panel is determined by its current consumption or, which is the same, by the voltage across the resistor through which the loop is powered. When smoke detectors are included in the loop, the loop current will increase by the amount of their total current in standby mode. Moreover, its value for detecting a break in the loop should be less than the current in the standby mode of an unloaded loop.

The transfer of several discrete signals to the analog signal of the loop occurs using a digital-to-analog conversion of the weighting type.

Sign-variable

The method of monitoring the alarm loop with power supply of the loop with alternating pulsed voltage provides an increase in the load capacity of the loop for powering current-consuming detectors. Resistor and diode connected in series are used as remote elements of alarm loops; in a direct voltage cycle, it is included in reverse direction and there are no losses. In the reverse cycle, due to its short duration, the losses are also insignificant. The signal "Fire" is transmitted in the positive component of the signal, "Fault" - in the negative. To continue operation when a “Fault” signal is issued due to the detector removed from the base, a Schottky diode is installed in the base. Thus, the “Fault” signal due to a removed detector or a malfunction of a self-testing detector (for example, a linear one) does not block the “Fire” signal from a manual call point.

An alternating loop allows the use of self-testing detectors in threshold loops. When a malfunction is detected, the detector automatically withdraws itself from the alarm loop, and this allows it to be used in conjunction with any fire alarm control panel, since detector withdrawal control is a mandatory requirement for fire safety standards for all control panels.

With pulsating voltage

The control method with power supply of the alarm loop with pulsating voltage is based on the analysis of transient processes in the loop loaded on the capacitor.

Address loops

In addressable fire alarm interrogation systems, fire detectors are periodically polled, their performance is monitored and a faulty detector is identified by a control panel. The use of specialized processors with multi-bit analog-to-digital converters, complex signal processing algorithms and non-volatile memory in fire detectors of this type provides the ability to stabilize the sensitivity level of the detectors and generate various signals when the lower limit of auto-compensation is reached when the optocoupler is contaminated and the upper limit when the smoke chamber is dusty.

Address polling systems are quite simply protected from breakage of the address loop and short circuit. In polling addressable fire alarm systems, any type of loop can be used: ring, branched, star, any combination of them and no end elements are required. In polling address systems, it is not required to break the address loop when the detector is removed, its presence is confirmed by responses when the receiving and control device is requested at least once every 5 - 10 seconds. If the receiving and control device does not receive a response from the detector at the next request, its address is displayed on the display with a corresponding message. Naturally, in this case, there is no need to use the loop break function, and when one detector is turned off, the operability of all other detectors is maintained.

To protect the address loop from short circuits, insulating bases are used, which, using electronic keys, automatically turn off the short-circuited section of the address loop.

IS loops

When protecting explosive premises with fire and burglar alarms, explosion protection of detectors is necessary and additional requirements are imposed on alarm loops. The choice of the brand of the detector should be carried out based on the category of the room according to the PUE. In the case of detectors marked "flame-proof enclosure", spark protection of the loop is not required.

Intrinsically safe loops will be connected to intrinsically safe terminals of intrinsically safe control and receiving devices, or through a spark protection barrier to conventional control and receiving devices.

Fire alarm loop- this is a communication line between the fire control panel, fire detectors and other devices designed to work in this line. Physically, the loop can be made through wired communication lines, fiber-optic communication lines, over a radio channel, etc. Most often, loops perform two main functions: receiving (transmitting) information from fire detectors and supplying power to the detectors. Wire loops, depending on the number of wires, are divided into two-, three-, four-wire, etc. As a rule, unaddressed communication reception and control devices and addressless fire detectors is implemented using a two-wire loop, i.e. the reception (transmission) of information from fire detectors and the power supply to the detectors are carried out via the same two-wire line. In this case, the control panel continuously monitors the current flowing in the loop and, depending on the magnitude of this current, can issue notifications: “Normal”, “Attention”, “Fire”, “Open”, “Short circuit”. Address loops fire alarm with addressable fire detectors included in them, they allow registering and displaying on the addressable control panel not only the operation mode of the detector, but also its address. Data exchange between the addressable control panel and detectors (exchange protocol), as well as the power supply of the detectors, can be performed in various ways. In order to separate the information exchange lines and the power lines of the detectors, three- and four-wire loops are often used, however, to reduce the cost of wired communication lines, many manufacturers of addressable systems transfer the supply voltage and exchange information between the device and the detectors via a two-wire loop. The exchange protocol (sequence, timing, amplitude and information content of pulses) in addressable fire alarm systems is not standard. Most often, it is developed by manufacturers of address systems for specific equipment or a series. The advantages of addressable loops are obvious, but there are certain difficulties in their development and application associated with electromagnetic compatibility problems. The presence of digital information exchange using pulse sequences leads to the fact that the induction of impulse noise on wired communication lines from external sources of electromagnetic radiation can lead to errors in the system. In this regard, as wired communication lines in addressable loops, it is advisable, and in some cases mandatory, to use a shielded wire or wires made in the form of a "twisted pair".

I. Not bad, Ph.D., Technical Director by ADT/Tyco PS

PART 1

The lack of classification of fire alarm loops and communication lines in fire automation systems in domestic standards is a significant drawback that determines the low level of performance of fire alarm systems, warning systems and fire protection systems. The principles of building threshold, multi-threshold and addressable analog loops have already been repeatedly discussed in the industry press, however, the increase in regulatory requirements in terms of ensuring the operability of loops and communication lines in a fire has led to the need to return to this topic again.

It is obvious that only the use of fire-resistant FRLS and FRHF cable does not provide a significant increase in system performance, disabling one detector blocks the “FIRE” signal from all other detectors in this loop. What is the use of using an expensive cable with a 3-hour fire resistance at a temperature of 750 ° C, if the device connected to it burns out 5 minutes after the start of the fire and thereby provides an open or short circuit in the communication line. Requirements for the performance of conventional and addressable fire alarm loops, unfortunately, they have not undergone any changes in terms of ensuring full or at least partial operability in the event of a break or short circuit of loops and communication lines. True, in new version GOST R 53325, apparently, short-circuit insulators for ring and radial loops will be introduced, but when the requirements for their mandatory use will be determined and in what form is still unknown.

On the other hand, in the manuals of foreign conventional devices and addressable modules of non-addressable sub-loopbacks, the possibility of forming and programming various styles and classes of loops and communication lines is determined, but the methodology for their selection, taking into account our regulatory requirements, is not given. The first part of the article mainly deals with the classification of loops according to NFPA72, and the second part of the article will analyze specifications addressable modules of non-addressable sub-loopbacks and addressable control modules when programming various styles and classes.

NFPA72 LINE CLASSES AND STYLES

Communication lines with actuators, with sirens, alarm loops with fire detectors, and so on, can only be either class A or class B. Alarm loops and communication lines with actuators that, with a single break or not simultaneously with a single short circuit to the ground of any conductor retain the ability to generate an alarm from any fire detector of this loop, or which ensure the operation of all devices connected to that communication line, are defined as class A.

Tab. 1. Classes and styles of a loop with detectors

P - Fire; H - Malfunction; N+A - Fire in the presence of a malfunction

Alarm loops and communication lines with actuating devices, which under these conditions ensure the transmission of an alarm signal only from fire detectors to the break point and do not ensure the operability of devices beyond the break point or a single ground fault of any conductor of the alarm loop or communication line, are defined as class B.

Moreover, if the conductor of the loop or communication line is broken, or if it is shorted to the ground, a fault signal should be generated within 200 seconds. No other classes of loops with other properties, for example, which do not ensure the operation of detectors not only after the break point, but also before it, are not classified, and their use in fire automation systems is not allowed.

Class B loops are subdivided by style into A, B, and C. They must all provide fault detection in the event of a single break in any conductor of the loop or a single short to ground. In case of a short circuit of the style A and B loops, a “Fire” signal is generated, and a “Fault” signal is generated for the style C loop. In style B and C loops, a fault like a single conductor short circuit to ground should not block the formation of the “Fire” signal (Table 1).

Class A plumes are divided by style into D and Ea. They should provide fault detection in the event of a single break in any conductor of the loop or its single short to ground. In case of a short circuit of the style D loops, a “Fire” signal is generated, and a “Fault” signal is generated for the Ea style loop. In style D and Ea loops, a fault such as a single break in the loop conductor or a single short circuit of the conductor to ground should not block the formation of the “Fire” signal (Table 1).

Thus, taking into account the requirements of GOST R 53325 on loop failure monitoring not only in the event of a break, but also in case of a short circuit, when programming a loop style, you can select only style C for a class B loop and style Ea for class A. In style A, B loops and D, a shorted loop will generate a false alarm.

To understand the technical implementation when meeting the requirements for class A and B loops, consider what recommendations are given in NFPA72 Appendix C on how to test them.

CHECKING LUBS OF DIFFERENT CLASSES AND STYLES

Class B 2-Wire Loops (Style A, B, and C) Operation with Firemen smoke detectors It is recommended to check as follows. Break the loop by removing the detector from the base or by disconnecting the loop conductor. Activate the smoke detector, which is located between the control panel and the loop break, as recommended by the manufacturer of this type of detector. After that, install the removed detector in the base or restore the loop connection, or do both. The control panel should indicate a malfunction after a loop break and generate an alarm when the detector is activated, despite the presence of a loop break. It should be noted that class B can include both radial loops (Fig. 1a) and ring loops (Fig. 1b), while all detectors that remain connected to the alarm loop output must be able to detect a fire, and detectors located behind the break in the loop are in the off state. Class B ring loops are formed in non-address threshold systems when the end element of the loop is located in the control panel. In this case, there is much more reliable information about the change in the state of the loop during operation by analyzing the change in voltage at the input and output of the loop compared to the traditional radial loop with a terminal element at the end of the loop.

Rice. 1. Class B loops (style A, B or C)

Rice. 2. Class A plume (style D and E)

Functioning of class A two-wire loops (style D and Ea) with fire detectors is recommended to be checked as follows. Break the conductor in the middle part of the loop by removing it from the broadcaster and disconnecting the conductor from the base contact. Activate the detectors on both sides of the loop break (Fig. 2). After that, reset the device to standby mode, restore the loop connection and install the detector. Then repeat the test when any conductor of the loop is shorted to ground in the place where the detector was turned off. In both tests, the audible and visual indication of the fault must first turn on, and then the alarm indication, followed by recovery. Unlike a class B loop, a class A loop is converted into 2 stubs when a break is detected, and all detectors continue to function despite the presence of a fault. This is verified during testing.

Communication lines with devices of any type used in fire automatics are classified in a similar way. For all types of devices included in the communication lines, it remains necessary to fulfill the requirement to ensure the operability of devices connected before the break in the communication line in class B, and to maintain the operability of all devices, regardless of their location relative to the break in class A. But for each individual type of device, depending from fulfilling other requirements various types device faults identified various styles, which are denoted by various letters or numbers. For example, communication lines with class B annunciators (Fig. 3), in addition to the obligatory provision of operability of annunciators before the communication line breaks, must meet additional requirements defined for style W or for style Y. And communication lines with class A annunciators (Fig. 4), in addition to ensuring the operability of all annunciators before and after a break in the communication line, they must meet additional requirements defined for style X or style Z.

Rice. 3. Communication lines with Class B sirens of W and Y styles

Rice. 4. Communication lines with class A sirens of styles X and Z

The principle of division into classes B and A must also be carried out when using communication lines with devices various types. For example, Figure 5 shows loops with addressable and addressable analog devices of various types: detectors and annunciators. A class B radial loop ensures the operability of all devices until the loop breaks, and a class A ring loop ensures the operation of all devices, both in standby mode and in fire mode, despite the presence of a malfunction. In the address system, if there is no response from the devices behind the break during the poll, the output circuits of the ring loop are switched to work in the mode of two radial loops. The fault is automatically localized by the distribution of devices between the two formed radial loops and it is determined between which addressable devices the loop has broken.

It must be emphasized that devices with communication lines or loopbacks that do not meet the requirements for class A or B are not classified and cannot be used in fire control systems according to NFPA72. For example, if, in the event of a break in the radial loop, the detectors that remain connected to the device are unable to generate the “FIRE” signal perceived by the device against the background of a malfunction, then such a system does not meet the requirements for class B loops and cannot be operated, despite its operability at no malfunction. In the same way, if the ring loop breaks anywhere, it is not allowed that at least several devices cease to function in standby mode or in the “Fire” mode.

Rice. 5. Loop with detectors and class B annunciators

Rice. 6. Loop with detectors and class A sirens

REQUIREMENTS GOST R 53325-2009

In our regulatory framework, there are no similar requirements for the classification of loops, although, obviously, it is impossible to compensate for their low fault tolerance by installing three detectors instead of one. In GOST R 53325-2009, clause 7.2.1.1, there is a requirement that FACPs must provide "preferential registration and transmission to external fire notification circuits in relation to other signals generated by FACPs." Despite the fact that the same wording was still present in the 75-98 airbags of the last century, there are a lot of certified control panels on our market, in which a fire notification is not registered if there is a signal about a loop malfunction, even if the terminating resistor and all of the broadcasters are turned off remain connected to the control panel and detect a fire, the Fire signal is disabled.

Ring addressable loops, despite their potential advantages over radial non-addressed ones, in our design cannot always be classified in class A. The method for checking the operation of devices in the event of a malfunction in our normative documents missing, and there are no performance checks in the event of a loop break. In addition, loopback outputs can be combined on the board, and then a single loop break is not detected by the device. True, if the cable cross-section is chosen to be minimal, then in the event of a break, the voltage drop can be significant and a large number of addressable devices cease to function.

Sometimes installers, even on foreign analog addressable devices with separate loopback outputs, parallel them in order to “eliminate” a malfunction that occurs due to a significant voltage drop on the loop with a small cable cross section. But when the loop breaks, this error manifests itself in the form of a drop in the loop voltage below the permissible value and turning off a significant part of the devices.

For clarity, let's consider an abstract example: a ring loop with a voltage of 20 V, about 1 km long, with a total current consumption of addressable devices of about 100 mA. The total resistance of the cable with a cross section of 0.2 mm2 is about 200 ohms. Assuming uniform distribution devices along the length of the loop, the current for each output of the parallel loop will be approximately equal to 50 mA, and taking into account the linear change along the loop, the average current in each half of the loop can be read as 25 mA. Accordingly, at a distance of 500 m at a resistance of 100 ohms, the voltage will drop by about 2.5 V. That is, the loop is powered in parallel, and due to this, a relatively small voltage drop is obtained. And if you disconnect one of the loop inputs from the device, then the average loop current will be summed up and increase to about 50 mA. Accordingly, over the entire length of the loop with a resistance of 200 ohms, the voltage drop will increase by 4 times and amount to 10 V!

Rice. 7. Failsafe loop

REQUIREMENTS FZ No. 123 AND GOST R 53316-2009

On the other hand, we have been living under the influence of federal law No. 123, where Article 82 unambiguously formulates the requirements for ensuring the preservation of operability in a fire of cable lines and electrical wiring, fire protection systems, means of ensuring the activities of fire departments, fire detection systems, warning and management of evacuation of people in case of fire, emergency lighting on evacuation routes , emergency ventilation and smoke protection, automatic fire extinguishing, internal fire water supply, elevators for transporting fire departments in buildings and structures during the time necessary to perform their functions and evacuate people to a safe area.

To meet this requirement, the use of fireproof cable low smoke FRLS and even smokeless and halogen free FRHF with more than 3 hours fire resistance. However, it soon became clear that the fire resistance of such a cable is not ensured if there is no mechanical fastening when exposed to high temperature. Accordingly, the fire-resistant cable must have a fire-resistant fastening and it is no longer allowed, as before, to put it in a corrugation with fastening on polyethylene dowels, which instantly burn out at a temperature of 750 ° C, which leads to the destruction of the fire-resistant cable.

GOST R 53316-2009 was released, which defined test methods for cable lines, which are required to maintain operability in a fire. This GOST defines a cable line: “a line designed to transmit electricity, its individual impulses or optical signals and consisting of one or more parallel cables with connecting, locking and end sleeves (seals) and fasteners, laid in accordance with the requirements of technical documentation , in boxes, flexible pipes, on trays, rollers, cables, insulators, free hanging, as well as directly on the surface of walls and ceilings and in the voids of building structures or in another way.

But the cable lines and electrical wiring of fire protection systems, means of ensuring the activities of fire departments, fire detection systems, warning and control of the evacuation of people in case of fire, emergency lighting on evacuation routes include automatic and manual call points, sound and light annunciators, and so on, which must also retain, if not operability, then the ability to "transmit electricity". In fact, they are "connecting ... couplings" and must also be tested in accordance with GOST R 53316-2009 as part of a cable line.

How can the requirements of the Technical Regulations be considered fulfilled when using a fire-resistant cable, if in a room where a fire broke out, after a few minutes, a burned-out annunciator short-circuits or breaks the communication line and turns off all other annunciators without waiting for people to be evacuated to a safe area? A burned out detector can block the formation of the “Fire” signal until the procedure for rechecking it is completed by resetting and waiting for confirmations from other detectors. One of possible solutions This problem is the use of ring loops and communication lines when constructively ensuring the absence of a short circuit of the device terminals in case of fire and when the short circuit insulators of the loop are turned on (Fig. 8). It is possible that there are more optimal solutions this problem. Obviously, a reliable assessment of the correctness of the chosen solutions can be determined by analyzing the results of "field tests" of systems under fire conditions, which, unfortunately, we have in abundance.

PART 2

​In the first part of the article, published in issue No. 5 of the Security Algorithm magazine for 2012, a foreign classification of fire alarm loops and communication lines in fire automation systems was considered. The second part of the article discusses the technical implementation of loops of different classes and styles. Given electrical parameters radial loops of class B, style C, ensuring the operability of detectors up to the point of a break in the loop; and ring loops of class A, styles D and E, ensuring the operability of detectors before and after a break. The use of a style D loop makes it possible to distinguish between the operation of automatic and manual fire detectors.

In conclusion to the first part of the article, it was said that the lack of classification of loops in domestic standards is a significant drawback that determines the low level of performance of fire alarm systems, warning systems and fire protection systems. Indeed, to what style and class can the loops of domestic control and reception devices be attributed? Maybe we're fine as it is? Not at all, regulatory requirements have recently changed more than once, a lot additional requirements was introduced to improve the performance of fire automation systems in a fire. The Technical Regulations on fire safety requirements Article 82. paragraph 2 says: “Cable lines and electrical wiring of fire protection systems, means of ensuring the activities of fire departments, fire detection systems, warning and control of evacuation of people in case of fire, emergency lighting on evacuation routes, emergency ventilation and smoke protection, automatic fire extinguishing, internal fire water supply, elevators for transporting fire departments in buildings and structures must remain operational in a fire for the time necessary to perform their functions and evacuate people to a safe area.

To fulfill this requirement, fire-resistant FRLS and FRHF cables began to be used in communication lines and fire alarm loops, but its breakage still puts the loop into the "Fault" mode, and the "Fire" signals from fire detectors are blocked in almost all domestic fire appliances . There were no requirements for maintaining the operability of communication lines and loops with detectors and annunciators in a fire. Foreign experience in ensuring full (class A) and partial (class B) operability of fire alarm loops in the event of a break is also not used. The new version of GOST R 53325, as well as in NPB 75-98, states that the control panel should only provide "preferential display and transmission to external fire notification circuits in relation to other signals generated by the control panel." There is no clear requirement on the inadmissibility of blocking the "Fire" signals by any other signals in our standards, and, accordingly, are not used technical solutions to meet this requirement.

Not only do we have non-addressed devices with class A ring loops, but also radial loops do not fit into class B of style D. On the other hand, almost all control panels are multi-threshold, which determines a low level of performance even while maintaining the integrity of the loop, not to mention the operation of fire detectors when loop break.

The unacceptably high probability of false alarms from smoke detectors due to the lack of protection against electromagnetic interference, regular maintenance and for many other reasons, as a result, has led to the fact that the "Fire" signal from the fire detector has ceased to be considered as such. Paradoxical as it may seem, but for many it has already become customary that now in domestic fire alarm systems any fire detector already generates only the “Attention” signal, and the “Fire” signal is formed by the combined efforts of two fire detectors.

The use of this terminology led to the development of an appropriate algorithm for the operation of control panels. An approximate algorithm for the functioning of domestic devices is shown in Table 1. The “Attention” signal from the first fire detector can be blocked by the “Fault” signal with an appropriate response to it. Although, in the conditions of the development of an open fire, there is a high probability of a break or short circuit in the loop before the second fire detector is activated. Protection against false alarms cannot be provided by reducing the level of fire safety. Why don't security loops use similar methods of protection against false positives? There are no “Attention” signals, nor two-threshold loops with at least 3 security detectors in the room. Moreover, in the event of a break, a short circuit of the loop, and even just a change in the resistance of the loop, an “Alarm” signal is quite logically generated. Perhaps the likelihood of theft is much higher, but the lack of fire protection creates a real threat to the population, not to mention incomparable material losses.

Perhaps many readers who have become familiar with foreign requirements for the classification of fire loops and communication lines have the impression that this is only a theory. That it is technically difficult to ensure the determination of the formation of the “Fire” signal by a fire detector when the loop breaks. And that ring loops are used only in addressable systems, but certainly not in traditional non-addressed ones.

Consider the principles of building class B loops of styles B, C and class A of styles D, E using the example of a multifunctional module of non-address sub-loop DDM800 addressable analog fire system Zettler (Fig. 1). This module can be programmed to work in various modes, including can support two class B radial loops of style C (short circuit of the loop is defined as a malfunction), or style B (short circuit generates a “Fire” signal) (Fig. 2), or one class A loop loop of style E (short short circuit is defined as a fault), or style D (short circuit generates a “Fire” signal) (Fig. 3), with terminal elements in the form of resistors or zener diodes, when using detector bases with diodes, and operate in 4-20 mA protocol mode . A different reset duration of the detectors and a polling interruption mode without verification or with verification are programmed with a different time for rechecking the confirmation of the “Fire” signal, depending on the type of detectors (Fig. 4). Depending on the mode of operation, it can occupy from one to four addresses. Non-addressed sub-loop power supply can be provided either from an addressable analog loop (Fig. 2) or from an additional power supply with galvanic isolation (Fig. 3).

Tab. 1. The algorithm of the fire loop

Rice. 1. Electronics of the DDM800 module

Rice. 2. Two class B radial loops powered by an addressable analog loop

Rice. 3. Loop loop class A powered from an external source

Tab. 2. Modes of operation of non-addressed sub-loop

Tab. 3. Algorithm of operation of non-addressed loop of class A and B

In addition, the DDM800 module operates as part of an analog addressable system and transmits to the panel not the "Fire" and "Fault" signals, but much more informative and easy-to-analyze analog values ​​associated with loop currents. These numerical values ​​are broadcast with a polling period of 5 s and are displayed on the panel display (Fig. 5-7).

What parameters should the loop have to ensure the possibility of receiving the “Fire” signal from fire detectors in the event of a break in the radial loop? First of all, it should be noted that in class A and class B loops, the use of series-connected broadcasters with normally closed contacts is not allowed. An indispensable condition for their work is the absence of a break in the loop. When the loop breaks, all detectors before and after the break point are not able to change the voltage and current of the loop. In class A and B fire loops of any style, only fire detectors connected in parallel in the loop can be used.

For radial loops of class B, the parameters must be selected in such a way that, with sufficiently large technological margins, it would be possible to identify the standby mode of the detectors and the activation of the detector, both with a working loop with a terminating resistor, and with a break in the loop at any place. Table 2 shows the modes of operation of a non-addressed loop. The maximum allowable current consumption of firefighters from the broadcasters in standby mode is 2.5 mA, which is significantly less than the loop break current threshold, which is 3.2 mA. Therefore, even if there is a break at the end of the loop, the current consumption of the detectors in standby mode will be less than the break current, and the fault will be identified. The minimum loop current in standby mode due to the terminating resistor is 4.2 mA, with the maximum number of fire detectors it can increase to 6.7 mA. A wide range of loop currents in the "Fire" mode from approximately 10.5 mA to 24.5 mA provides reliable formation of the "Fire" signal both in the case of a maximum loaded loop and in case of a break. Even if only one of the broadcasters remains connected to the module as a result of a loop break, when the detector current in the "Fire" is more than 10.5 mA, the control panel fixes the "Fire" mode. On the other hand, as a rule, in foreign and domestic detectors there are zener diodes that exclude the transition of the loop into a short circuit mode even if several detectors go into a fire at the same time. In this case, as a rule, no additional resistors are required to be connected to the detectors.

Rice. 4. Programming the operating modes of the DDM800 module in the MZXConsys program

In contrast to the operation algorithm of domestic receiving and control devices, the unconditional priority of the “Fire” signal is provided in the logic of operation of foreign loops. Regardless of the previous state of the loop, as soon as its parameters fall into the range corresponding to the "Fire" mode, it is fixed by the addressable analog panel (Table 3).

To ensure the operability of all detectors in the event of a line break, a class A loop loop structure without branches is used (Fig. 3). In standby mode, power is supplied only from the A terminals, and the loop terminating resistor is connected to the B terminals. This can be seen from the loop current-related analog values ​​that are transmitted to the control panel when polled. When the current of the detectors in standby mode is 2.5 mA and the total loop current is 6.7 mA, the analog value for output A is 035. Output B is disabled, and its analog value is correspondingly 001 (Fig. 5).

If a loop break occurs, the part of the loop connected to the B terminals remains without power for the duration of the fault identification. By regulatory requirements the fault detection time should not exceed about 100-200 s, in reality it takes about 60 s. If a break occurs near the B terminals, then the current on output A is reduced by the current consumption of the terminating resistor and becomes 2.5 mA, the analog value decreases to 015, and the current on output B remains zero for 60 s, and its analog value remains equal to 001 (Fig. 6).

After detecting a break in the loop loop, output B turns on and two radial loops are formed, respectively, the value of the analog value for output B becomes 023, which corresponds to a current of 4.2 mA, which consumes a 4.7 kΩ termination resistor connected to terminals B (Fig. 3).

Rice. 5. Indications of the loop loop in standby mode

Rice. 6. Class A loop in break detection mode

Rice. 7. Loop loop with a break is converted into two radial

When using automatic and manual detectors in one loop, the type of activated detector can be determined. The "Fire" signal from a manual call point works by interrupting the polling of the addressable analog loop, in the so-called Fast CallPoint mode. Reaction to activation automatic detector is programmable separately and can also be with polling abort, or with verification by requerying the status, or without verification. The control panel indicates the operation of manual and automatic call points at different addresses, indicating the type of detector. Accordingly, when using two class B radial loops in Fast CallPoint mode, four addresses are used in total, and when using a class A loopback loop, two addresses are used. Moreover, a manual call point with normally open contacts is connected without an additional resistor and transmits the “Fire” signal by short circuiting the loop, that is, class A style D and class B style B loops are implemented. The use of these modes is currently problematic according to our standards, since the serviceability of the loop for open and short circuits must be monitored, but interest in the experience of implementing the 2-threshold mode is obvious.

In addition to the fact that in the Fast CallPoint mode, to introduce the second threshold, the signal from manual call points is transmitted by a short circuit of the loop, and the short circuit current of the loop is doubled, up to 50 mA. Accordingly, the operating current range of the loop is extended (Table 4). As a result, the loop current range from 0 to 50 mA is divided into 4 parts corresponding to the loop break mode, standby mode, Fire mode from an automatic detector, and Fire mode from a manual call point. Naturally, the "Fire" modes are also formed in the presence of a break in the loop.

For comparison, in domestic devices, the loop current range is twice as small, from 0 mA to 20-25 mA, 5 modes for the smoke loop and 7 modes for the combined loop fit in, and if the loop breaks, the only reliable signal remains "Fault", and the signals "Fire" from detectors that have worked in the future are not accepted by the FACP.

Tab. 4. Thresholds of class A, style D loopback with automatic and manual call point detection (Fast CallPoint mode)

Thus, the use of class A, style E loop loops makes it possible to ensure the operability of all detectors in the event of a loop break, not only in addressable analog, but also in conventional traditional systems. When laying a loop loop in different zones, this can significantly increase the performance of the loops in a fire.

LITERATURE:

1. Not bad I. Classes and styles and trains. Ensuring performance. Part One // "Security Algorithm". -2012. - No. 5.

2. Not bad I. Loop control, protection against breakage and short circuit / / "Safety Algorithm". - 2005. - No. 5.

3. Not bad I. Unaddressed subloop in the address-analogue system // "Security Algorithm". - 2007. - No. 6.

4. Not bad I. Gas fire extinguishing: requirements of British standards // Security Systems. - 2007 - No. 5.

5. Not bad I. Classification of conventional loops, or Why there are no two-threshold devices abroad // Security Algorithm. - 2008. - No. 3.

6. Neplokhov I. Analysis of the loop parameters of a two-threshold control panel // Security Algorithm. - 2010. - No. 5.

7. Neplokhov I. Analysis of the loop parameters of a two-threshold control panel. Part 2 // "Security Algorithm". - 2010. - No. 6.

8. Neplokhov I. Analysis of the loop parameters of a two-threshold control panel. Part 3 // "Security Algorithm". - 2011. - No. 1.

9. Not bad I. Problems of connecting heat detectors with indicators / / "Fire safety - 2011". - Grotek.

10. GOST R 53325-2012 Fire fighting equipment. Technical means of fire automatics. General technical requirements. Test methods.

11. NFPA 72, National Fire Alarm Code.

PART 3

In the first and second parts of the article, published in Nos. 5, 6 of the Security Algorithm magazine for 2012, a foreign classification of fire alarm loops and communication lines in fire automation systems was considered. The third part of the article discusses the technical implementation of communication lines of different classes and styles. The parameters of class B radial communication lines according to the NFPA72 classification are given, which ensure the operability of annunciators up to the point of a loop break and class A ring communication lines, which ensure the operability of annunciators before and after a communication line break.

FEDERAL LAW REQUIREMENTS

Federal Law No. 123-F3 of July 22, 2009 "Technical Regulations on Fire Safety Requirements" introduced requirements for ensuring the operability of fire protection systems in case of fire. Article 51 "The purpose of creating fire protection systems", paragraph 3 says: "Fire protection systems must be reliable and resistant to the effects of fire hazards for the time necessary to achieve fire safety goals." Further, in paragraph 4 it is said: "The composition and functional characteristics of fire protection systems for objects are established by regulatory documents on fire safety." In addition, article 84 “Fire safety requirements for systems for warning people about a fire and managing the evacuation of people in buildings and structures”, paragraph 7. says: “Systems for warning people about a fire and managing the evacuation of people must function for the time required to complete the evacuation of people from the building, structure. Also in article 84, paragraph 6. “The design and characteristics of the smoke protection elements of buildings and structures, depending on the goals of smoke protection, should ensure the correct operation of supply and exhaust smoke ventilation systems for the time necessary to evacuate people to a safe zone, or for the entire duration of the fire.

NORMATIVE BASE

Accordingly, requirements were made to improve performance fire fighting systems in a fire in the regulatory framework. In the first edition of the Code of Rules SP 6.13130.2009 “Fire protection systems. Electrical equipment. Fire safety requirements" it was stated that "cable lines of fire protection systems should be made of fire-resistant cables with copper conductors that do not spread combustion during group laying according to category A according to GOST R IEC 60332-3-22 with low smoke and gas emission (ng-FRLS ) or halogen-free (ng-FRHF)”, and “cable lines of warning and evacuation control systems (SOUE) and fire alarms involved in ensuring the evacuation of people in case of fire must remain operational in fire conditions for the time required for complete evacuation people to the safe zone.

On February 25, 2013, a new Code of Rules SP 6.13130.2013 was put into effect, in which mandatory requirement there is no use of a fire-resistant cable, it is only indicated that "Electric cable lines and electrical wiring of the SPZ must be carried out with cables and wires with copper conductive conductors."

In addition, the Code of Rules SP 3.13130.2009 “Fire protection systems. Fire warning and evacuation control system. Fire safety requirements" contains a general technical requirement: "Cables, wires of the SOUE and methods of their laying must ensure the operability of connecting lines in a fire during the time necessary for the complete evacuation of people to a safe area."

Thus, the domestic regulatory framework considers ways to ensure the operability of communication lines when using a fire-resistant cable and laying methods. Circuit solutions that improve the performance of communication lines, for some reason, have not yet been considered. An expensive fire-resistant FRLS and FRHF cable is used, but there is no protection of the communication line from an elementary break. The new version of GOST R 53325-2012 introduces requirements for short-circuit insulators (IKZ) for addressable loops and communication lines, but the Code of Practice does not define requirements for their mandatory use. Moreover, in most domestic addressable systems, the mandatory introduction of IKZ into addressable loops is a half measure, since the communication lines with the RS-485 protocol, through which modules with addressable loops are connected to the hub, still remain unprotected from breakage and short circuit. In the event of a malfunction in these communication lines, the entire one, several or all addressable loops with all detectors, modules, annunciators and IKZ are turned off. The introduction of requirements to ensure the failure of no more than 32 devices, in the event of an open or short circuit of any communication lines, and not just loops, automatically leads to the use of loopback communication lines.

Another significant drawback of our spontaneously arising heuristic principles for constructing communication lines with control modules is the lack of control of the communication line with the power source and the presence of voltage at the module input. Usually, only the control line to the relay module is monitored, which also determines the low operability of the system.

COMMUNICATION LINES WITH SIGNALERS ACCORDING TO NFPA72-2013

In the 2002 version of NFPA72, communication links were defined with class A style Z sirens and class B style W, X and Y sirens. In subsequent editions, only classes A and B were left for sirens without their division into styles. Class B lines provide operability when one conductor is shorted to the ground with the formation of fault signals (Fig. 1), but do not ensure the operability of annunciators beyond the break point. Class A communication lines have a backup channel, provide operability in the event of a single break or a single short circuit of one of the conductors to the ground with the formation of fault signals (Fig. 2).

Moreover, class A communication lines made using physical conductors, for example, copper or optical fiber, must be laid separately: outgoing conductors and conductors returning to the control unit. Laying in one way and using a 4-core cable is allowed, provided that the length of the communication line is not more than 10 feet (3.0 m), only one device is connected, or several sirens installed in one room with an area of ​​\u200b\u200bnot more than 1000 ft2 (93 m2 ).

In addition, there is a requirement that ring loops or communication lines do not pass through the same room twice. Thus, when using short-circuit insulators, high system operability is ensured both under normal conditions with mechanical damage to the loop, and in fire conditions.

ADDRESS-ANALOGUE MODULES

There is no mistake in the subtitle, as it might seem to some readers who are not familiar with the equipment of the world's leading manufacturers. In fact, to increase the level of control of the state of communication lines in the addressable analog system, the modules transmit to the panel not the fault codes "Open" and "Short Circuit", but analog values ​​associated with the resistance of the communication line. Depending on the level of current consumption of the annunciators in the "Fire" mode, various technical solutions can be used. In the simplest case, at relatively low load currents, for example, up to 75 mA, the annunciators are powered from an addressable analog loop, and controlled through transistor switches. The LPS800 siren control module has two pairs of outputs S+ S- and R+ R-. A class B radial communication line with a terminating resistor is connected to the S+ S- outputs (Fig. 3). The class A ring line is connected to the S+ S- and R+ R- outputs, and the terminating resistor is connected to the R+ R- terminals (Fig. 4). In this case, the annunciators are powered from both outputs simultaneously and, despite the break in the communication line, they all remain operational.

In both cases, the analog addressable panel controls the break and short circuit of the communication line by analog values ​​of current and voltage, determined in the standby mode by the terminating resistor. Figure 5 a, b, c shows the analog values ​​on the display of the addressable analog panel, received from the LPS800 module with the address A249, respectively, for the standby mode, the communication line break mode and the communication line short circuit mode.

Annunciators with high consumption currents up to 2 A are powered from an external power source so as not to overload the analog addressable loop, and control is performed using a polarized relay. Accordingly, the SNM800 sirens control module, in addition to two pairs of outputs S+ S- and R+ R- for connecting sirens, additionally has two pairs of I+ I- terminals for connecting an external power source and connecting power to the next module (Fig. 6, 7). When using a class A ring communication line, the annunciators are powered from both outputs and, despite the break in the communication line, all of them remain operational (Fig. 7). At the same time, the analog addressable panel controls the voltage of the external power supply at the module input according to the readings of the analog values ​​transmitted by the SNM800 module, and generates the "Fault" and "Fault of sirens" signals when the supply voltage drops.

a) standby mode; b) communication line break mode; c) mode of short circuit of the communication line

NON-ADDRESSED MODULES

To control sirens with high consumption currents up to 15 A, additional non-addressable modules - sound boosters (Fig. 8) can be used.

The module contains 2 relays, dual terminals for connecting an external power source and for connecting a radial communication line with sirens. Inflows up to 10 A can be connected to codinary terminals, for high currents it is necessary to use a parallel connection of each conductor, as shown in Figure 9. The SB520 module is connected to the communication line of the LPS800 module or the SNM800 module through the I / P terminals, and the terminating resistor is connected to the EOL terminals. The sound booster relay module provides control of communication lines with sirens and control of external supply voltage at the input. When a fault is detected, the SB520 module disconnects the EOL terminating resistor and thereby transmits a fault signal through the address module LPS800 or SNM800 to the control panel.

Thus, modern technical solutions with class A communication lines according to the NFPA72 classification, which ensure the operability of all annunciators in the event of a communication line break, and relay modules with monitoring of the communication line and voltage of an external power source, can significantly increase the operability of fire fighting systems in fire conditions. It should also be noted that in domestic standards there are no requirements for the classification of loops and communication lines, which leads to the widespread use of only radial communication lines that are inoperable in case of breaks. The absence of clear requirements in the regulatory documents for the control of communication lines allows the use relay modules without monitoring the presence of supply voltage, which significantly reduces the level of monitoring the performance of fire protection systems.

To be continued...

LITERATURE

1. Not bad I. Classes and styles and trains. Ensuring performance. Part 1 // "Security Algorithm". - 2012. - No. 5.

2. Not bad I. Classes and styles and trains. Ensuring performance. Part Two // "Security Algorithm". - 2012. - No. 6.

3. NFPA 72-2013 National Fire Alarm Code.

4. No. 123-FZ Technical regulation on fire safety requirements.

5. Code of Practice SP 6.13130.2009 “Fire protection systems. Electrical equipment. Fire safety requirements.

6. GOST R IEC 60332-3-22-2005 Tests of electrical and optical cables under flame conditions. Part 3-22. Flame propagation along vertically arranged bundles of wires or cables. Category A.

7. Code of Practice SP 6.13130.2013 “Fire protection systems. Electrical equipment. Fire safety requirements.

8. Code of Practice SP 3.13130.2009 “Fire protection systems. Fire warning and evacuation control system. Fire safety requirements.

9. GOST 53325-2012 Fire fighting equipment. Technical means of fire automatics. General technical requirements. Test methods.