1. Cable selection
The wiring design of the TV monitoring system involves video monitoring lines, radio intercom lines, alarm lines, sound monitoring lines, and network lines. Their functions are different, and the type of cable to choose is also different.
1. The commonly used video transmission cable for camera video signal transmission cable is 75Ω series thin coaxial cable, but the degree of attenuation of the video signal by coaxial cable with different wire diameters is also different. The thicker the cable, the smaller the attenuation. . The characteristic parameters of the coaxial cable series are shown in Table 1. Requires cable selection according to Table 1. The thicker the wire diameter of the cable, the smaller the attenuation, and the more suitable for long-distance transmission.
The cable selection is as follows: when the distance from the camera to the sub-monitoring center is less than or equal to 300 meters, SYV-75-3 can be selected; when the distance from the camera to the sub-monitoring center is less than or equal to 500 meters, SYV-75-5 can be selected; When the center distance is less than or equal to 800 meters, SYV-75-7 or SYV-75-9 can be selected; when the distance from the camera to the sub-monitoring center is less than or equal to 1000 meters, SYV-75-12 can be selected;
2. Camera power cable The power cable in the TV monitoring system is wired separately, and a master switch is set in the monitoring room to directly control the entire monitoring system through the UPS power supply. Converted to DC 12V by the adapter. However, some cameras use 5V or 12V, 24V DC, and the power supply method is different.
3. Use a camera device cable with an electric pan/tilt head and a motorized lens. For a camera device with an electric pan/tilt head and a motorized lens, in addition to the above video signal cables and cables, the transmission line between the on-site decoder and the control center should also be considered Generally, 2-core shielded communication cable (RVVP) or Category 3 twisted pair is used, and the cross-sectional area of UTP core is 0.3m㎡~0.5mm㎡.
4. Alarm and sound monitoring cables The alarm and monitoring cables in the warehouse and corridor are generally 4-core shielded communication cable (RVVP) or Category 3 twisted pair UTP, and the cross-sectional area of each core is 0.5m㎡.
5. Broadcasting and intercom cables When setting broadcasts in the warehouse, corridor, factory area, etc., the basic principle of the cable is: the longer the distance, the thicker the cable. The basic communication distance stipulated by RS-485 communication is 1200 meters. In practice, the RVV-2/1.5 sheathed cable is used in the project, which can extend the communication distance to 2000 meters. The length of the visual distance for broadcasting and intercom is different. Cable, twisted pair.
6. Computer network cables Computer network cables are divided into two categories. One type of vertical trunk lines and optical cables are used between buildings, and the other type of horizontal trunk lines are 4 pairs of 8-core shielded Category 5e cables. According to the actual situation of the prison project, the high-grade 50μm/125μm optical cable of YOFC Optical Fiber and Cable Co., Ltd. was selected between the buildings. The multi-film optical cable is used for sub-monitoring to the sub-monitoring center, and the single-film optical cable is used for the sub-monitoring center to the general monitoring center. Use 4-pair/8-core Category 5 shielded twisted pair cables from the work area to the management room.
2. Design of wiring system
The wiring system of a prison is divided into video, broadcast intercom, monitoring alarm transmission, and data transmission. Video transmission, broadcasting, intercom, monitoring, alarm transmission line. According to the specifications and standards of the integrated wiring system. It is designed as work area subsystem, horizontal trunk subsystem, vertical trunk subsystem, management room subsystem, equipment room subsystem and building management subsystem. The distribution of each subsystem is reasonable and the structure is clear. The strong and weak currents are routed separately. Learn more about the data transmission line below. In the process of data transmission, multi-film optical cable, single-film optical cable, and shielded super 5 twisted pair are used. Multi-film optical cable is used between buildings with a distance of ≤2000 meters; single-film optical cable is used between buildings with a distance of >2000 meters; shielded Category 5e twisted pair is used between the desktop and the management room. Basic link length ≤ 90 meters, channel link length ≤ 100 meters. Weak current signals go through metal wire troughs in vertical trunk lines and horizontal trunk lines, and PVC troughs in some sections. When entering the supervision warehouse or working area, they are generally buried in hidden pipes according to safety requirements. Only in the place where the police officers work or when the construction is difficult, it will be changed to open trough. When the cable bends, the twisted pair maintains a curvature radius of 10 to 15 times, and the PVC hose or metal hose is sleeved at the bend. Optical cables are all routed through cable trenches, and when passing through the road, they are introduced into the management room through buried iron pipes. When the optical cable turns, keep the curvature radius of 15~20 times.
3. Construction of wiring system
During the wiring construction, the construction shall be carried out in strict accordance with the relevant provisions of the integrated wiring system design specification. During the wiring construction, the following requirements are proposed for different locations and environments, and those that cannot meet the requirements must be reworked.
1. The exposed wire grooves are required to ensure a service life of 10 to 15 years without being affected by external forces. Therefore, different installation requirements are proposed for grooves of different specifications:
(1) When the size of the wire groove is less than 25㎜×30㎜, install a fixing screw every 15㎝～25㎝ distance;
(2) When the size of the wire duct is less than 50㎜×50㎜, install two fixing screws every 15㎝～30㎝ distance, and require dislocation installation;
(3) When the size of the wire duct is less than 30㎜×100㎜, install three fixing screws every 15㎝～30㎝ distance, and require dislocation installation;
(4) In principle, metal open grooves are installed with brackets (the brackets are spaced at a distance of 1 to 1.5 meters). In the areas where brackets cannot be installed, three fixing screws should be installed at a distance of 15 cm to 30 cm, and dislocation is required. Install;
(5) When there is an "S"-shaped "Z" bend in the pipe layout, the junction box is installed, and the hose is used when it is not easy to bend.
2. The wiring ducts of cameras, broadcasting, intercom, monitoring, and alarm points where the hidden pipes are laid are all buried wiring. If there are pre-embedded pipes in the past, they can be used as much as possible. When it cannot be used, break the wall and set up pre-buried pipes. In principle, the load-bearing wall shall not be slotted or drilled, but in some places, due to the special needs of construction, both parties A and B jointly negotiate and consider, and open shallow slots. Holes are not allowed.
3. Vertical trunk wiring
When running vertical trunk lines, use existing weak current wells and weak current pipelines. Cables are in weak current wells and weak current pipelines. No kinks, no cross hairs allowed, it must be kept straight. Bundle it every 1.5 meters or so and fix it with a "U" clip to eliminate the displacement of the cable due to gravity. 4. Other requirements for wiring A prison wiring involves TV monitoring lines, radio intercom lines, monitoring lines, power lines, alarm lines, network lines, etc. Requirements for wiring:
(1) Separate wiring for strong current and weak current, and take their own pipelines;
(2) Keep a distance of 10 cm to 30 cm when the strong current and weak current pipelines are routed in the same direction in the horizontal direction;
(3) When the strong current and weak current pipelines are perpendicular to each other, the respective casings are used to avoid the interference of strong current to weak current;
(4) Both ends of various lines are marked;
(5) Termination points are not allowed in the middle of signal lines and video lines;
(6) In principle, the power cord is not allowed to have a connection point in the middle, and a junction box must be added in case it occurs;
(7) Signal lines, data lines, power lines, etc. should be straight in their respective grooved tubes, without twisting and knotting;
(8)When the hose is connected with the hard pipe, the hose and the hard pipe should be firm and reliable when entering the groove. After all kinds of cables are laid, their performance is tested according to the requirements of the wiring standard and meets the specified technical indicators.
