People are accustomed to referring to the weak current technology as weak current technology. It can be seen that the basic meaning of weak current technology in smart buildings is still the weak current technology in the original sense. However, with the rapid development of modern low-current technology, the application of weak-current technology in intelligent buildings is becoming more and more extensive. Such as intelligent fire protection system, monitoring system, computer network, building automation, intelligent broadcasting and so on. The degree of application of weak current technology determines the degree of intelligence of intelligent buildings.
Commonly used building weak current systems mainly include the following :
(1) Telephone communication system
Realize the communication function of telephone ( including three types of fax machines, video phones, etc. ) ; star topology ; use three types ( or above ) unshielded twisted pair, and the frequency of the transmission signal is within the audio frequency range.
(2) Computer Local Area Network System
It is the network foundation for realizing office automation and various data transmission ; star topology ; using Category 5 ( or above ) unshielded twisted pair cables to transmit digital signals, the transmission rate can reach more than 100 Mb/s .
(3) Music / Broadcasting System
Play music through speakers installed on site ( such as shopping malls, stations, restaurants, guest rooms, corridors, etc. ) , and broadcast the scene through microphones ; multi-channel bus structure ; transmission of constant voltage output by power amplifiers ( such as 120 V /120 Ω ) audio signal to drive the sound of the live speaker, the transmission line uses copper core insulated wire.
(4) CATV signal distribution system
Distribute the cable TV signals evenly to each user point in the building ; use branchers and distributors for signal distribution, in order to reduce signal distortion and attenuation, and make the signal quality of each user point meet the requirements of the specification, the wiring is a tree structure , and varies with the form of the building and the distribution of user points ; use 75 Ω RF coaxial cable to transmit multiple RF signals.
(5) Video surveillance system
Through the cameras, anti-theft detectors and other equipment installed on the site, the entrances and exits of the building and some important places are monitored and alarmed for abnormal situations ; the transmission of video signals adopts a star structure and uses video coaxial cables ; the transmission of control signals Adopt bus structure and use copper core insulated cable.
(6) Fire alarm system
The system consists of three parts: fire alarm and fire linkage system, fire broadcast system, and fire alarm intercom telephone system.
The fire alarm and fire linkage system monitors the on-site situation through fire detectors and manual alarm devices installed in various places in the building. equipment to control the spread of fire, and its signal transmission adopts a multi-channel bus structure, but for the transmission of linkage control signals of important fire fighting equipment ( such as fire pumps, sprinkler pumps, positive pressure fans, smoke exhaust fans, etc. ) , sometimes star-shaped Structure, signal transmission using copper core insulated cable ( some products require the use of twisted pair ) .
The fire-fighting broadcasting system is used to instruct 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 ( the system can be used with music / broadcasting systems ) .
The fire alarm intercom telephone system is used to instruct the on-site firefighters to carry out fire extinguishing work.
(7) Entrance and exit control system / all-in -one card system
Use computers, smart card door locks, card readers and other equipment to set, monitor, control and record the status of each entrance and exit, realize unified management of all entrances and exits of the building, and ensure the safety of the building. Its topology and transmission media vary by product .
(8) Parking lot fee management system
Through the induction coil installed under the entrance and exit ground, the entry and exit of vehicles are sensed, and the manual / semi-automatic / automatic toll management system is used to realize the toll collection and control the opening and closing of the electric railings. The wiring of the system is limited to the entrances and exits of the building yard. Each entrance and exit is controlled by a controller. The controller can work independently or be networked with the upper management computer. The wiring structure and transmission medium vary from product to product.
(9) Building automation system
通过与现场控制器相连的各种检测和执行器件，对大楼内外的各种环境参数以及楼内各种设备(如空调、给排水、照明、供配电、电梯等设备)的工作状态进行检测、监视和控制，并通过计算机网络连接各现场控制器，对楼内的资源和设备进行合理分配和管理，达到舒适、便捷、节省、可靠的目的。到目前为止，楼宇自控系统还没有国际标准，不同厂家的产品所采用的通信协议各不相同，其现场总线和控制总线的拓扑结构和传输介质也就不同。下面将对目前被国际社会普遍接受和采纳的LonWorks技术和BACnet技术作简单介绍。
此外，还有电视会议系统、屏幕显示系统、扩声系统、巡更系统、楼宇对讲系统、三表(水、电、气表)自动抄表系统等。不同功能的建筑物需要设置的弱电系统各不相同。