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First, cable selection
The wiring design of the TV monitoring system involves video monitoring lines, broadcast intercom lines, alarm lines, sound lines, and network lines. Their functions are different, and the models of the selected cables are also different.
Camera video signal transmission cable
The commonly used video transmission cable is a 75Ω series of thin coaxial cable, but the coaxial cable with different wire diameters has different attenuation degrees to the video signal, and the thicker the cable, the smaller the attenuation. The characteristic parameters of the coaxial cable series are shown in Table 1. It is required to select cables according to Table 1.
The thicker the cable diameter, the smaller the attenuation, and the more suitable for long-distance propagation. Select the cable as follows:
When the distance from the camera to the sub-monitoring center is ≤300 meters, SYV-75-3 can be used;
When the distance from the camera to the sub-monitoring center is ≤500 meters, SYV-75-5 can be used;
When the distance from the camera to the sub-monitoring center is ≤800 meters, SYV-75-7 or SYV-75-9 can be used;
When the distance from the camera to the sub-monitoring center is ≤1000 meters, SYV-75-12 can be used;
2. Camera power cord
The power cable in the TV monitoring system is separately wired. The main switch is set in the monitoring room. The UPS power supply is used to directly control the entire monitoring system. Under normal circumstances, the power cable is wired according to AC 220V, and then converted to DC by the adapter at the camera end. 12V. However, some cameras use 5V or 12V, 24V DC power, the power supply method is different.
3. Use camera cable with electric pan/tilt and motorized lens
In addition to the above video signal lines and cable lines, the camera unit with electric pan/tilt and motorized lens should also consider the transmission cable between the field decoder and the control center. Generally, it adopts 2-core shielded communication cable (RVVP) or class 3. Twisted pair, UTP core cross-sectional area is 0.3m~0.5m.
4. Alarm and sound
The alarm and warehouse cables at the warehouse and the corridor are generally selected from 4-core shielded communication cable (RVVP) or Category 3 twisted pair UTP, with a cross-sectional area of ​​0.5 m per core.
5. Broadcast and intercom cables
When setting up broadcasts in warehouses, corridors, factories, etc., the basic principle of cables is: the longer the distance, the thicker the cable. The basic communication distance specified by RS-485 communication is 1200 meters. In practice, RVV-2/1.5 sheathed cable is used in the project, which can extend the communication distance to 2000 meters. The length of the broadcast and intercom can be different depending on the length of the distance. Cable, twisted pair.
6. Computer network cable
Computer network cables are divided into two categories. One type of vertical trunk line and fiber optic cable are used between buildings, and the other type is 4 pairs of 8-core shielded super 5 type line for horizontal trunk line. According to the actual situation of the prison project, the advanced 50μm/125μm fiber optic cable of Changfei Fiber Optic Cable Co., Ltd. was selected between the buildings. Multi-film cable is used for sub-monitoring to sub-monitoring center, and single-film optical cable is used for sub-monitoring center to total monitoring center. 4 pairs/8 cores and 5 types of shielded twisted pair cables are used in the work area to the management room.
Second, the design of the wiring system
The wiring system of a certain prison is divided into video, broadcast intercom, jian listening alarm transmission, and data transmission. Video transmission, broadcasting, intercom, alarm transmission line. According to the specifications and standards of the integrated wiring system. Designed as work area subsystem, horizontal trunk subsystem, vertical trunk subsystem, management subsystem, equipment subsystem, building management subsystem. Each subsystem has a reasonable distribution and a clear structure. Strong and weak electricity are routed separately. Let's take a look at the introduction of data transmission lines. Multi-membrane cable, single-film cable, and shielded super 5 twisted pair are used in the data transmission process. Multi-film cables are used between buildings with a distance of ≤ 2000 m; single-film cables are used between buildings with a distance of > 2000 m; shielded Category 5 twisted pairs are used for desktop to management rooms. The basic link length is ≤ 90 meters and the channel link length is ≤ 100 meters.
The weak electric signal is in the vertical trunk line and the horizontal trunk line. A total of metal troughs are taken. In some sections, the PVC trough is taken. When entering the warehouse or working area, the buried pipe is generally taken according to the safety requirements. In the place where the police are working or the construction difficulties, it is changed to the open slot. When the cable is bent, the twisted pair maintains a radius of curvature of 10 to 15 times, and the PVC hose or metal hose is sleeved at the corner. The optical cable runs through the cable trench. When passing through the road, it is introduced into the management room through the buried iron pipe. When the cable is bent, maintain a radius of curvature of 15 to 20 times.
Third, the construction of the wiring system
During the construction of the wiring, the construction shall be carried out in strict accordance with the relevant provisions of the design rules for the integrated wiring system. When wiring, the following requirements shall be made for different locations and environments. Any failure to meet the requirements must be reworked.
1. Place the wire trough
The open line slot requires a 10- to 15-year service life without external force, so different installation requirements are required for different sizes of slots:
(1) When the wire slot specification is less than 25×30, install a fixing screw every 15 to 25 distances;
(2) When the wire slot specification is less than 50×50, install two fixing screws at intervals of 15 to 30, and require dislocation installation;
(3) When the wire slot specification is less than 30×100, install three fixing screws at intervals of 15 to 30, and require dislocation installation;
(4) In principle, the metal clear groove is installed by brackets (the distance between the brackets is 1 m to 1.5 m), and the brackets cannot be installed. The distance between the brackets is 15 to 30, and three fixing screws are installed, and the dislocation is required to be installed;
(5) When the “S†type “Z†turns when the pipe is installed, the wire box is installed, and the hose is not easy to bend.
2. Where the dark tube is placed
The cable slots of the camera, broadcast, intercom, and alarm points are all buried in the buried line. If you have a pre-embedded tube, you can use it as much as possible. When it is not possible to use it, the wall is then slotted to set up the pre-embedded pipe. In principle, the load-bearing wall can not be slotted or punched, but in some places, due to the special needs of construction, both parties A and B jointly negotiate and consider to open shallow slots. Holes are not allowed.
3. Vertical trunk wiring
When the vertical trunk line is routed, the existing weak electric well and weak electric pipeline are used. The cable is in weak electric wells and weak electric pipes. Kinking is not allowed, no payment is allowed, and it must be kept straight. Bundle once every 1.5 meters, use the "U" clip to fix the displacement of the cable caused by gravity.
4. Other requirements for wiring
A certain prison wiring involves television monitoring lines, broadcast intercom lines, jian listening lines, power lines, alarm lines, network lines, and so on. Requirements for wiring:
(1) Separate the power from the weak electricity and take the respective pipelines;
(2) Maintain a distance of 10 to 30 between the strong and weak current pipelines in the same direction in the horizontal direction;
(3) When the strong electricity and the weak electricity pipeline are perpendicularly intersected*, the respective casings are used to avoid the interference of the strong electricity to the weak electricity;
(4) Marking both ends of various lines
(5) Termination points are not allowed in the middle of the signal line or video line;
(6) In principle, the power cord is not allowed to have a connection point in the middle, and a wire box must be added in case of occurrence;
(7) Signal lines, data lines, power lines, etc. should be straight in the respective groove tubes, without distortion or knotting;
(8) When connecting the hose to the hard pipe, the hose and the hard pipe should be firm and reliable when they are grooved.
After the various cables are laid, they are tested according to the requirements of the wiring standards and meet the specified technical specifications.