April 13, 2023
1. Cable selection
The wiring design of television monitoring system includes video control lines, intercom lines, signaling lines, sound monitoring lines and network lines. Their functions are different, and models of selected cables are also different.
1. Camera video cable
Commonly used video transmission cables are thin 75 ohm series coaxial cables, but coaxial cables with wires of different diameters have different degrees of video attenuation. The thicker cable, less attenuation. Characteristic parameters of a series of coaxial cables are shown in Table 1. Cables must be selected according to Table 1.
The larger wire diameter of cable, lower attenuation and more suitable for long distance transmission. Select cable as follows:
If distance from camera to sub-monitoring center is less than or equal to 300 meters, you can select SYV-75-3;
If distance from camera to sub-monitoring center is less than or equal to 500 meters, you can select SYV-75-5;
When distance from camera to sub-monitoring center is ≤800 meters, you can choose SYV-75-7 or SYV-75-9;
When distance from camera to sub-monitoring center is less than or equal to 1000 meters, SYV-75-12 can be selected;
2. Camera Power Cord
The power lines in TV monitoring system are connected separately, and main switch is installed in monitoring room, and UPS power supply is used to directly control entire monitoring system. As a rule, power lines are connected according to 220 V AC, and then through adapter at end of camera, it is converted to 12 V DC. However, some cameras use DC 5V or 12V, 24V, and power supply method is different.
3. Use a camera cable with motorized head and motorized lens
For a camera device with a motorized pan/tilt and a motorized lens, in addition to above-mentioned video signal wires and cables, transmission cable between field decoder and control center should also be considered, usually using a 2-core shielded communication cable (RVVP ) or Category 3 twisted pair, UTP core cross-sectional area is 0.3m²~0.5m².
4. Alarm and sound control cable
Prison and corridor signaling and prison cables generally use 4-core shielded communication cables (RVVP) or Category 3 UTP twisted-pair cables, and cross-sectional area of each core is 0.5m㎡.
5. Broadcast and Intercom Cables
When broadcasting in prisons, corridors, factory areas, etc., basic principle of cable is: greater distance, thicker cable. The basic communication range provided by RS-485 communication is 1200 m. In practice, project uses a protected wire РВВ-2/1.The early connection can be selected according to length of cable distance, twisted pair.
6. Computer network cable
Computer network cables fall into two categories. One type of vertical trunk line and fiber optic cables are used between buildings, and other type is a horizontal trunk line with 4 pairs of 8-core super category 5 shielded lines. According to actual situation in prison project, a high-quality 50 µm / 125 optical cable was selected between buildings µm from YOFC Optical Fiber and Cable Co., Ltd. Multi-film optical cables are used from sub-monitoring centers to sub-monitoring centers, and single-film optical cables are used from sub-monitoring centers to general monitoring centers. 4-pair/8-core Category 5e shielded twisted-pair cables are used from work area to control room.
Second, design of wiring system
The prison wiring system is divided into video, intercom, alarm transmission control and data transmission. Video transmission, broadcasting, intercom, monitoring, alarm transmission lines. According to norms and standards of integrated electrical wiring system. It is designed as work area subsystem, horizontal trunk line subsystem, vertical trunk line subsystem, control room subsystem, control room subsystem and building management subsystem. The distribution of each subsystem is reasonable and structure is clear. Strong and weak currents are directed through slots, respectively. Learn about data link below. The data transmission process uses multi-film optical cables, single-film optical cables and super-5 shielded twisted pairs.
Multifilm optical cable is used between buildings at a distance of ≤2000 meters;
Single-film optical cable is used between buildings at a distance of >2000 meters;
Category 5e shielded twisted-pair cables are used from desktop to control room. Baseline length ≤ 90 meters, channel channel length ≤ 100 meters.
Low-level signals are routed through metal wire troughs on vertical and horizontal trunk lines, and in some areas through PVC troughs. Prison or work area entrances typically use underground pipes to meet safety requirements. It is changed to open grooves only in places where police work or when construction is difficult. When cable is turned, twisted pair keeps radius of curvature from 10 to 15 times, and PVC hose or metal hose is twisted at corner. All optical cables pass through cable trench, and when passing through road, they are introduced into control room through buried iron pipes. When bending optical cable, observe bending radius of 15 to 20 times.
Third, construction of electrical wiring system
The design of electrical wiring is carried outare strictly in accordance with relevant provisions of integrated wiring system design specification. The following requirements are put forward for different locations and environments when installing wiring. Those that do not meet requirements must be recycled.
1. The place where groove for wiring is laid out
Open slots require a service life of 10 to 15 years without external force, so slots with different characteristics have different installation requirements:
(1) If box size is less than 25㎜×30㎜, install fixing screw every 15㎝～25㎝;
(2) If duct size is less than 50㎜×50㎜, please install two fixing screws at 15㎜～30㎜ interval, it requires dislocation installation;
(3) If duct size is less than 30㎜×100㎜, install three fixing screws at intervals of 15㎜～30㎜, and offset installation is required;
(4) Metal exposed channels are usually installed using brackets (brackets spaced at intervals of 1 to 1.5 m). In places where brackets cannot be installed, three mounting screws are installed at intervals of 15 cm to 30 cm. And requires dislocation installation;
(5) When there is a "S" type "Z" turn when laying pipe, a wire box is installed and a hose is used when turn is difficult.
2. Place of laying a hidden pipe
Cameras, broadcast, intercom, monitoring, and alarm points all use hidden flush wiring. If there are pre-buried pipes, use them as much as possible. When it cannot be used, pre-embedded pipe is installed by breaking wall and slot. In principle, neither grooves nor holes can be drilled on load-bearing walls, but in some places, due to special needs of construction, parties A and B agree and consider joint opening of smaller grooves. Holes are not allowed.
3. Vertical backbone routing
Use existing low-flow wells and low-flow pipelines when laying vertical trunk lines. Cables are located in low-current wells and pipelines. No kinks are allowed, no crosshairs are allowed, they must remain straight. Tie it up every 1.5 meters or so and secure with a U-clip to prevent cable from shifting due to gravity.
4. Other wiring requirements
Prison wiring includes television surveillance lines, radio communication lines, surveillance lines, power lines, alarm lines, network lines, etc.
Wiring requirements:
(1) Separate wiring for strong and weak electricity and use your own piping;
(2) Keep a distance of 10㎝～30㎝ when high-current and low-current pipelines are laid in same direction in horizontal direction;
(3) When high-current and low-current pipelines cross vertically,they must have a separate clutch to avoid influence of a strong current on a weak one;
(4) Both ends of different lines are marked
(5) Termination points are not allowed in middle of signal lines and video lines;
(6) In principle, it is not allowed to have a connection point in middle of power cord, and in case of such a situation, a junction box must be added;
(7) Signal lines, data lines, power lines, etc. must be straight in their respective grooves, without twists or knots;
(8) When connecting hose and rigid pipe, hose and rigid pipe must be strong and secure when entering groove.
After laying all types of cables, their performance must be checked for compliance with requirements of electrical wiring standards and compliance with specified technical indicators.
