Industry News

Cable Identification II

2021-03-30





Cable Identification II


The selection of monitoring cable

Cable selection

 

1,CCTV cable

 

The distance between the camera and the monitoring host is less than or equal to 200 meters, using RG59 (128 series) video cable.

 

The distance between the camera and the monitoring host is more than 200 meters, using SYV75-5 video cable.

 

2, PTZ control cable

 

The distance between the pan/tilt and the controller is 100m, and use RVV6×0.5 sheathed cable.

 

The distance between the pan/tilt and the controller is more than 100 meters, using RVV6×0.75 sheathed cable.

 

3, Lens control cable

 

Use RVV4×0.5 sheathed wire.

 
4, Decoder communication cable

should use RVV2×1 shielded twisted pair

 

5, Camera power cord

 

If the system has 20 ordinary cameras, and the average distance between the camera and the monitoring host is 50 meters, the BVV6m2 copper core double plastic wire should be used as the main power line. The power lines used at different distances are shown in the following table:

 

The average distance between the camera and the monitoring host is 34~50m 21~33m20m

 

Power cord specifications (2 lines) 6m24m22.5m2

 

Monitoring system line laying

 

1. Cautions for laying the video cable

 

1.1. If the distance between the camera and the monitoring host (image processor, matrix control host or digital video recorder) is less than 200 meters, the RG59 video cable can be used. If it exceeds 200 meters, the SWY-75-5 video cable should be used to ensure the monitoring image the quality of.

 

1.2. For cameras installed in elevators, galvanized iron troughs should be used for wiring in the elevator shaft and grounded to reduce the interference to the video signal when the elevator motor starts.

 

1.3. If the camera is installed outdoors (such as the entrance of a compound or a parking lot, etc.), the line needs to be routed outdoors or through overhead steel cables. If conditions permit, video arrestrs should be installed (because the installation of lightning protection equipment will cause The total project cost increases), that is, one video arrester is installed on the camera side and the monitoring host side respectively, and each video arrester must be grounded (outdoor cameras must be grounded separately, and the video arresters in the monitoring room can be grounded uniformly), To prevent damage to the equipment caused by induction lightning.

 

2. Precautions for laying control wires

 

2.1. In the analog monitoring system, if a camera equipped with a pan/tilt zoom lens is installed and controlled by a pan/tilt lens controller, the control line should be selected according to the distance between the camera and the pan/tilt lens controller. When the distance is less than 100 meters, the pan/tilt control line can use RVV6×0.5 sheathed line; when the distance is greater than 100 meters, the pan/tilt control line should use RVV6×0.75 sheathed line, and the lens control line uses RVV4×0.5 Sheathed cable.

 

If the analog monitoring system controls the pan/tilt and the lens through a matrix control host, a decoder is generally required. For the control circuit layout, please refer to the technical requirements of the matrix control host used.

 

2.2. In the digital surveillance system, if a camera equipped with a pan/tilt zoom lens is installed, the pan/tilt and lens need to be controlled through a decoder. The decoder is generally installed next to the camera, and the decoder and the digital video recorder use RS485 bus to communicate. Wiring should use RVVP2×1 shielded twisted-pair cable from the digital video recorder to the nearest decoder 1, and then from decoder 1 to decoder 2... The current 16-channel digital video recorder can connect up to 16 decoders. The total length of RS485 communication line can be up to 1200 meters. The wiring diagram is as follows: see the relevant posts in the basic knowledge.

 

The decoder has two power supply types: AC220V and AC24V. If an AC24V decoder is selected, it is generally supplied by an AC24V transformer. It is particularly important to note that due to the interference of the DC12V power supply output by some decoders, it will have a certain impact on the image when used for camera power supply, so it is necessary to uniformly supply the camera (12V).

 

3. Cautions for laying the power cord of the camera

 

The operating current of ordinary cameras on the market that use DC12V power supply is about 200~300mA, and the integrated cameras are 350~400mA. If the number of cameras is small (less than 5) and the distance between the camera and the monitoring host is relatively close (less than 50 meters), each camera can be individually wired with RVV2×0.5 power cord to the monitoring room and powered by a small transformer. If the number of cameras is large, a high-power 12V DC stabilized power supply should be used for centralized power supply.

 

In the program design and construction process, it is necessary to consider the total power of all cameras and the voltage drop caused by the transmission line (commonly known as "line loss", the resistance of 1m2 copper wire per 100m is 1.8Ω). For the monitoring of a building, two 2.5-6m2 copper core double-plastic wires are generally used as the main power supply to lead from the monitoring room to the line well, and walk along the line well to the line well on the floor where each camera is located. For the power supply of each camera on the floor, one RVV2×1 or RVV2×1.5 (if the number of cameras on this floor exceeds 6) power cords can be used to supply power to the cameras, or use RVV2×0.5 sheath wires for one-to-one correspondence powered by.