Connection Among Generic Cabling, Alarm and Fire Communication System

Overview of automatic fire alarm system

The overview of the automatic fire alarm system described here is the most basic content. Automatic fire alarm system is an application system with multiple technical functions of detection, alarm and fire extinguishing control. It involves multiple disciplines and disciplines. Therefore, it must be understood, especially the parts related to generic cabling system, which is conducive to cooperative design.

The automatic fire alarm system is mainly composed of fire detection alarm, fire alarm control equipment and control lines between them. Therefore, it is a huge system organically combined by various components, devices and equipment. They work together to undertake the important task of disaster prevention and alarm. Because the fire detection alarm is more important in the automatic fire alarm system and is related to the generic cabling system. This paper briefly introduces the general situation of fire detection and alarm at present.

1) Relationship between automatic fire alarm system and other systems

In order to ensure that state property is not damaged and people's lives are safe. It is required that in intelligent buildings and intelligent communities, especially in key departments and important places, practical and effective disaster prevention and fire extinguishing facilities with functions of timely fire detection, rapid automatic alarm and linkage control must be set and configured.

Therefore, it is necessary to set up automatic fire alarm system, fire linkage control system and fire communication system, considering that the construction scale, use object and coverage of intelligent buildings and intelligent communities are different. Therefore, the construction scale and specific contents of the above three systems are also different, but the fire communication system is an indispensable part.

2) Type, wiring system and connection mode of fire detection alarm

Fire detection alarm is referred to as fire detector or fire alarm, commonly known as probe. It is an important part of the automatic fire alarm system. It is distributed in all important parts of the whole intelligent building. It is the "sensory organ" of the automatic fire alarm system. It closely monitors and detects its surrounding environment at any time and anywhere.

It cooperates with the fire alarm control equipment, and the automatic fire alarm control equipment is not only the "body" and "brain" of the automatic fire alarm system, but also the core of the system. They are an inseparable combined whole that complement and cooperate with each other.

â‘  Wiring system and connection mode of fire detection alarm

In the automatic fire alarm system and fire fighting linkage control system, the fire detection and alarm subsystem is the most important part, and its cables are most widely distributed, because the fire detection and alarm is set all over the internal parts of the intelligent building, and is suitable for the level of the protection object.

â‘¡ Types of fire detection alarm

At present, there are many kinds and types of fire detection alarms produced at home and abroad, so its classification methods are diverse and not unified. They are classified according to their technical performance and use requirements, and they are different. For example, they are classified according to different fire detection parameters of fire detection alarms, including smoke sensing type, temperature sensing type, photosensitive type, combustible gas detection type Compound type and other 10000 types;

If classified according to its structural shape, it can be divided into point type and line type; If classified according to its use environment, it can be divided into land type, marine type, cold resistant type and acid resistant type. Alkali resistant type and explosion-proof type, etc. The above types can be subdivided into different types. Classification according to fire parameters is usually adopted in China. Therefore, the number of cables (i.e. wire system) and connection mode of fire detection and alarm subsystem are very important, which is also related to the cable distribution and utilization of generic cabling system.

The wire system of fire detection alarm mainly refers to the number of wires of transmission signal lines between fire detection alarm and control equipment, which is mainly divided into multi wire system and bus system. Different connection modes are derived from different wire systems, mainly including two bus system, four bus system, multi wire system (n 4), and the combination of two bus system and ring network.

In addition, there are chain and other connection types. The above network structure, wiring system and connection mode have their own characteristics and are related to each other. Therefore, in general, the corresponding network structure, wire system and connection mode are selected based on the factors such as the range of detection and alarm area in the intelligent building, the distribution and allocation of fire detection alarm and so on.

Bus system: that is, an independent address circuit to judge the specific location of the fire. The alarm control equipment uses serial communication to access each detector. This kind of wire system and the number of connecting wires are significantly reduced, and the installation and construction is simple, so it is widely used at present. However, its disadvantage is that once there is a short-circuit fault in the bus circuit, the whole circuit will fail, can not work normally, and may even damage some detectors or control equipment.

Multi wire system: multi wire system is the link mode of live detection alarm used in the early stage. It is characterized in that a live detection alarm (or a group of several fire alarms) forms a loop and is connected with the fire control equipment. When any detector in the loop detects a fire, the loop of the detector is reflected on the control equipment, and its specific human position (i.e. ignition point) cannot be determined. Therefore, a single line must be added to each detector to form a multi wire system. The multi wire system is "n 4 wire system", n is the number of detectors, and 4 refers to common lines, which are power line (V, ± 24V), ground line (g), signal line (s) and self diagnosis break line (T). In addition, each detector is equipped with a strobe line (st).

Only when a strobe line is at the effective level, the signal transmitted on the signal line is the state information of the detection part. The advantage of this connection method is that the circuit of the detector is relatively simple. The observation information is more intuitive and it is easy to judge the specific location of the fire; the disadvantage is that there are a large number of conducting wires, the pipe diameter of the piping is thick, the threading construction is difficult and there are many line faults. Therefore, in In order to ensure the normal operation of the whole system, avoid accidents and reduce the maximum loss, short-circuit isolation measures must be taken in the system, such as installing short-circuit isolator in sections.

The four buses are: P line gives the power supply, coding and location signals of the detector; t line gives the self-test signal to judge whether the detection part or the transmission signal line is obstructed; the control equipment obtains the information of the detection part from the s line; g line is the public ground wire. The four lines P, t, s and G are connected in parallel. Because the bus system adopts the coding location technology, the control equipment can accurately To determine the specific location of the detected fire, simplify the installation and commissioning, and greatly improve the reliability of the system operation. The two bus system uses less wires than the four bus system, but the technology is more complex. It is more difficult. In the two bus system, the P line works for various functions such as power supply, site selection, self inspection and information acquisition, and the g line is the public ground wire.

At present, this kind of wire system and connection mode are widely used. Its network structure includes tree type and ring type. Tree type is often used in most systems at present; ring type, for control equipment, becomes access with four lines. In addition, there is chain connection mode, and its P line is connected in series with each fire detection alarm. For each detection alarm, there are three lines For control equipment, only two lines are connected.

From the various connection modes introduced above, it can be seen that except that the network forms a ring type, which provides relatively safe and reliable conditions for ensuring normal operation, other bus systems have the disadvantages of poor safety and reliability of the bus. Therefore, the advantages and disadvantages must be weighed and determined in the design.

Therefore, the fire communication system should be the infrastructure in intelligent buildings and intelligent communities, which must be paid attention to and set up.