China's national standards stipulate that fire alarm system, fire-fighting fire-fighting linkage control system and fire-fighting communication system must be installed in important occasions and key parts in intelligent buildings or intelligent communities. Among them, the fire automatic alarm system and the fire communication system have a close relationship with the integrated wiring system, but they have their own independent characteristics and requirements, and both parties must cooperate and coordinate with each other.
Overview of automatic fire alarm system
The overview of the automatic fire alarm system described here is the most basic content. The automatic fire alarm system is an application system with multiple technical functions of detection, alarm and fire control. It involves multiple disciplines and various professions. For this reason, it must be understood, especially the part related to the integrated wiring system. Conducive to the design.
The automatic fire alarm system is mainly composed of fire detection alarms and fire alarm control devices and control lines between them. Therefore, it is a huge system that is organically combined with various components and devices and equipment. They work together to undertake the important task of disaster prevention alarm. The fire detection alarm is more important in the automatic fire alarm system and is related to the integrated wiring system. This article provides a brief overview of current fire detection alarms.
1) Relationship between automatic fire alarm system and other systems
In order to ensure the state property is not lost and the people's lives are safe. It is required to set up and configure effective and effective fire prevention and extinguishing facilities such as fire detection, rapid automatic alarm, and linkage control in intelligent buildings and intelligent communities, especially in key departments and important places.
To this end, it is necessary to set up an automatic fire alarm system, a fire-fighting linkage control system, and a fire-fighting communication system, taking into consideration the construction scale, the object of use, and the coverage of intelligent buildings and intelligent communities. Therefore, the construction scale and specific content of the above three systems are also different, but the fire communication system is an indispensable component.
2) Types of fire detection alarms and wiring systems and connection methods
Fire detection alarms are referred to as fire detectors or fire alarms. They are commonly called probes. They are an important part of the automatic fire alarm system. They are distributed throughout the entire intelligent building. They are the “sensory organs†of the automatic fire alarm system. "Closely monitor and detect the surrounding environment at any time and any place."
It cooperates with fire alarm control equipment to cooperate with each other, and the automatic fire alarm control equipment is the "body" and "brain" of the automatic fire alarm system. It is also the core of the system. They are the inseparable joint combination of complement each other and cooperate with each other. .
1 wire detection and connection method of fire detection alarm
The fire detection and alarm subsystem in the fire alarm system and fire-fighting linkage control system is the most important part, and its cable distribution is the most extensive, because the fire detection alarm is located at various parts inside the intelligent building, and It is compatible with the level of the protected object.
2 types of fire detection alarms
At present, the types and types of fire detection alarms produced at home and abroad are extremely diverse, so the classification of them is diverse and diverse, and has not been unified. It is classified according to its technical performance and usage requirements, and is different, for example, according to fire detection. The alarm detects different types of fire-inducing parameters, such as smoke-sensing, temperature-sensing, photosensitive, flammable gas detection, composite and other types;
If it is classified according to its structural shape, it can be divided into two types: point type and line type; if it is classified according to its use environment, it can be divided into land type, marine type, cold type and acid type. Alkali-resistant and explosion-proof. The above various types can be subdivided into different types. Domestically, the classification of the parameters according to the fire is usually adopted. Therefore, the number of cables (ie, wire) and connection methods of the fire detection and alarm subsystem are extremely important, and are related to the cable distribution and utilization of the integrated wiring system.
The wire system of the fire detection alarm mainly refers to the number of wires of the transmission signal line between the fire detection alarm device and the control device, and is mainly divided into two types: a multi-wire system and a bus system. Due to the different connection methods derived from the different line systems, there are mainly two bus systems, four bus systems, multi-wire systems (n+4), and two bus systems combined with ring networks.
In addition, there are chain and other connections. The above network structure, wire system and connection method have their own characteristics and are related to each other. Therefore, under normal circumstances, it is based on the size of the detection and alarm area within the intelligent building, the distribution status and equipment of the fire detection alarm, and other factors, and the corresponding network structure, line system and connection type are selected.
Bus system: that is, an independent address circuit, in order to determine the specific location of the fire, the alarm control device uses serial communication to access each detector. The number of such wire-and-connected wires is significantly reduced, and the installation and construction are simple, so it is widely used at present. However, the disadvantage is that once a short circuit fault occurs in the bus circuit, the entire circuit fails, does not work properly, and may even damage some of the detectors or control devices.
Multi-line system: Multi-line system is an early use of the link method of detecting alarms. It features a live detection alarm (or a group of fire alarms) that form a loop that is linked to the fire control device. When any detector in the loop detects the fire, the loop of the detector is reflected on the control device and it is impossible to determine its specific location (ie, the ignition point). Therefore, each detector must be connected with a single wire. Form a multi-line system. The multi-wire system is "n+4-wire system, n is the number of detectors, and 4 is the common line. They are power lines (V, ±24V), ground (G), signal lines (S), and self-diagnostic lines. (T) In addition, each detector is provided with a gate line (ST).
Only when a gate line is at an active level, the signal transmitted on the signal line is the state information of the detected portion. The advantage of this type of connection is that the detector circuit is relatively simple. Observing the information is more intuitive, it is easy to judge the specific location of the fire; the disadvantage is that the number of wires is large, the pipe diameter of the pipe is thick, the threading construction is difficult, and the line faults are also many. Therefore, this type of wire system and connection method has been reduced in the country. Therefore, in order to ensure the normal operation of the whole system and avoid accidents, and to reduce the maximum loss, short-circuit isolation measures must be taken in the system, such as the installation of short-circuit isolators in sections.
The four buses are: P line gives the power, coding and location signals of the detector; T line gives the self-test signal. In order to judge that the detection part or the transmission signal line is unobstructed; the control device acquires the information of the detection part from the S line; the G line is the common ground line. The four lines P, T, S, and G are connected in parallel. Because the bus system adopts the coding and location technology, the control device can accurately determine the specific location of the detected fire, simplify the installation and debugging, and the reliability of the system operation is greatly improved. The two-bus system has fewer lines than the four-bus system, but the technology is more complicated. The difficulty has increased. In the two-bus system, the P line is used for power supply, site selection, self-test, and information acquisition. The G line is a common ground line.
At present, such wire system and connection methods are used more. Its network structure has a tree and a ring. Tree type, which is the method often used by most current systems; ring type, for control equipment, becomes 4 lines of access. In addition, there is a chain connection type, and its P line is connected in series with each fire detection alarm. There are 3 wires for each probe alarm, and for the control device, only 2 wires are connected.
From the various connection methods described above, it can be seen that except for the network forming a ring type, which provides safe and reliable conditions for ensuring normal operation, other bus systems have the disadvantage of poor safety and reliability of the bus, so at the time of design We must weigh the pros and cons and consider it in a comprehensive way.
The three of them complement each other into a whole, in order to give full play to their overall timely alarm and disaster prevention and extinguishment functions. Therefore, the fire communication system should be the infrastructure in intelligent buildings and intelligent communities, which must be paid attention to and set.
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