Introduction to the system function of the weak current project
Introduction to the system function of the weak current project. Commonly used building weak current systems mainly include the following: (1) The telephone communication system realizes the communication function of the telephone (including the three types of fax machines, video phones, etc.); the star topology structure; the use of three types (or Above) unshielded twisted pair, the frequency of the transmission signal is within the audio range. (2) The computer local area network system is the network foundation to realize office automation and various data transmission; star topology structure; use Category 5 (or above) unshielded twisted pair to transmit digital signals, and the transmission rate can reach more than 100 Mb/s . (3) The music/broadcasting system plays music through speakers installed at the scene (such as shopping malls, stations, restaurants, guest rooms, corridors, etc.), and can broadcast the scene through microphones; multi-channel bus structure; transmission is output by power amplifiers The audio signal of constant voltage (such as 120 V/120 Ω) is used to drive the live speaker to produce sound. The transmission line uses copper core insulated wire. (4) The cable TV signal distribution system evenly distributes the cable TV signal to all user points in the building; splitters and distributors are used for signal distribution, in order to reduce signal distortion and attenuation, so that the signal quality of each user point can meet the specifications. It is required that the wiring is a tree structure, and varies with the form of the building and the distribution of user points; 75 Ω radio frequency coaxial cable is used to transmit multiple radio frequency signals. (5) The video surveillance system uses cameras, anti-theft detectors and other equipment installed on-site to monitor the entrances and exits of the building and some important places, and alarm for abnormal conditions; the transmission of video signals adopts a star structure and uses video coaxial. Cable; The transmission of the control signal adopts a bus structure and uses a copper core insulated cable. (6) Fire alarm system This system is composed of three parts: fire alarm and fire fighting linkage system, fire broadcasting system, and fire alarm intercom telephone system. The fire alarm and fire-fighting linkage system monitors the on-site situation through fire detectors and manual alarm devices set up everywhere in the building. When there is an alarm signal, according to the received signal, according to the pre-set procedure, the corresponding linkage is linked. Equipment to control the spread of fire, its signal transmission adopts a multi-channel bus structure, but for important fire-fighting equipment (such as fire pumps, sprinkler pumps, positive pressure fans, exhaust fans, etc.) linkage control signal transmission, sometimes star-shaped Structure, signal transmission uses copper core insulated cables (some products require twisted-pair cables). The fire broadcasting system is used to direct the on-site personnel to evacuate safely in the event of a fire. It adopts a multi-channel bus structure and uses copper-core insulated wires for signal transmission (this system can be used with music/broadcasting systems). The fire alarm intercom system is used to direct firefighters on site to carry out fire fighting. It adopts two structures, star type and bus type, and shielded wires are used for signal transmission. (7) The entrance and exit control system/all-in-one card system uses computers, smart card door locks, card readers and other equipment to set, monitor, control and record the status of each entrance and exit to achieve unified management of the entrance and exit of the building to ensure the safety of the building. The topology and transmission medium vary from product to product. (8) The parking lot charging management system senses the entry and exit of vehicles through induction coils installed under the ground of the entrance and exit, and realizes charging and controlling the opening and closing of electric railings through the manual/semi-automatic/full-automatic toll management system. The wiring of the system is limited to the entrance and exit of the building's parking lot. Each entrance and exit is controlled by a controller. The controller can work independently or networked with the upper management computer. The wiring structure and transmission medium vary from product to product. (9) The building automation system uses various detection and execution devices connected to the field controller to monitor various environmental parameters inside and outside the building and various equipment in the building (such as air conditioning, water supply and drainage, lighting, power supply and distribution, elevators, etc.) The working status of) is detected, monitored and controlled, and each on-site controller is connected through a computer network to reasonably allocate and manage the resources and equipment in the building to achieve the goals of comfort, convenience, saving and reliability. So far, there is no international standard for building automation systems, and the communication protocols used by products of different manufacturers are different, and the topology and transmission media of their fieldbus and control bus are also different. The following will give a brief introduction to the LonWorks technology and BACnet technology that are currently generally accepted and adopted by the international community. Chengdu weak electricity project: There are also TV conference system, screen display system, sound reinforcement system, patrol system, building intercom system, three meter (water, electricity, gas meter) automatic meter reading system, etc. Buildings with different functions need different weak current systems.