Hello everyone, I'm Brother Xue. On the issue of choosing the power supply in the monitoring project, the novice may be a little confused, the power supply of the camera in the monitoring system is the premise of ensuring the normal and reliable operation of the monitoring equipment, how to reasonably arrange the power supply of the monitoring system and select the power cord, it is very important in the video surveillance system. Today we're going to take a look at the monitoring power application.
First, the setting of the power supply
The power supply of the camera is set according to whether the camera is on the side of the control host or a relatively long distance, if it is relatively close, a high-power DC regulated power supply is installed directly next to the host, and a plurality of cameras are connected to this power supply, and the DC power supply power is greater than the sum of the power of the camera.
If the distance is far, the 220V AC power supply should be allocated to the side of the camera, and then the voltage conversion power supply to the camera is supplied with power through the stabilized power supply, and the distance between the 220V AC power cord and the video cable should be greater than 30 cm to avoid magnetic field interference and affect the quality of image transmission.
Second, the choice of power supply
The power cord selection can be reasonably selected through calculation, and the working current of the commonly used 12V power supply camera:
Ordinary bolt or hemisphere: the working current is about 200~300mA, and you can choose a power supply of 500MA-1A
All-in-one camera: the working current is about 350~400mA, and you can choose a power supply of 1A
Small and medium-sized infrared camera: the working current is 600-700mA, and you can choose a power supply of 1A
Large infrared camera: working current 1000MA-1200mA can choose 2A power supply
Power supply in a monitoring system: the camera can be supplied separately, or a plurality of centralized power supply, if it is a centralized power supply of multiple cameras, the required current is the sum of the current of a plurality of cameras.
Example
Suppose a monitoring system wants 10 hemisphere cameras to share a power supply, because the current of a hemisphere is 300-400MA, so the current of 10 cameras is 3000MA-4000MA, you should choose 5A or 6A power supply.
3. Selection of power cord diameter
Assuming that the distance from four cameras to the monitoring is less than 40 meters, each camera can separately deploy RVV2×0.5 power cord to the monitoring host and use a small switching power supply for power supply; If there are 4 hemispheres or bolts, you can also choose 2 12V1A power supplies or 1 12V2A power supply, and the 4 cameras are connected in parallel to take power, which is more wire-saving;
If the number of cameras is large, 8 cameras, then the high-power 12V DC regulated power supply should be used for centralized power supply, at this time due to the excessive current, the voltage drop on the power line must be considered, under normal circumstances, the system of 8 cameras, the longest distance is not more than 40 meters, can be deployed RVV2 * 0.75 wire centralized power supply; If the system of 16 channels is centrally powered, it is necessary to choose the RVV2*1.0 power cable. The above is the selection of the power cord with a distance of no more than 40 meters from the camera to the monitoring host.
If the distance from the camera to the host is more than 40 meters, it is necessary to consider using 220V centralized power supply, and the voltage conversion to the camera end becomes 12V to supply power to the camera. Under normal circumstances, 220V power supply, as long as the system is not too big, less than 8 channels, within 200 meters of distance, you can choose RVV2 * 0.75 wire, if more than 8 channels, are high-power infrared cameras, you should consider using RVV2 * 1.0 power cord power supply, in addition, if the distance is farther, in order to ensure safety, it is best to use RVV2 * 1.5 wire.
Fourth, the selection method of the power cord
1. Twisted pair power supply
Category 5 or more unshielded twisted pair cables are used as power cables for surveillance cameras, which can simplify wiring, but you need to ensure that the power supply meets the requirements of the equipment. If the working power supply of the equipment is 10-12VDC, the current is 500MA, the internal resistance of the twisted pair is 10Ω/100 meters (the actual use of oxygen-free copper is 100m is 9.53Ω), if the power supply is 12VDC, considering the distance voltage attenuation, to ensure the normal use of the equipment, the transmission power supply is within 150 meters.
2. Independent RVV line power supply
According to the power of the terminal camera, the power of the general fixed bolt is not more than 10W, the infrared bolt is generally not more than 20W, and the dome is about 35W. Purely in terms of power, the line of RVV2*0.5 is sufficient, and the line of the national standard 0.5 can carry a load of about 1KW.
For long distances, considering the attenuation, it is recommended to use a line of not less than 1.0. If the number of cameras is small (less than 5) and the distance between the cameras and the monitoring host is close (less than 50 meters), each camera can be independently deployed RVV2×0.5 power cable to the monitoring room and powered by a small transformer.
If the number of cameras is large, a high-power 12V DC regulated power supply should be used for centralized power supply. During the construction process, the total power of all cameras and the voltage drop caused by the transmission line should be taken into account (called "line loss", the resistance of a copper wire with a specification of 1m2 is 1.8Ω per 100m).
For the monitoring of a building, two 2.5-6m2 copper core double plastic lines are generally used as the main power supply line from the monitoring room to the line well, and along the line well to the line well of each camera floor. For the power supply of each camera on the floor, the power supply can be supplied to the camera by a power supply cable of RVV2×1 or RVV2×1.5 (if the number of cameras on the floor exceeds 6), or the corresponding power supply of RVV2×0.5 sheath wire.
5. What to do with long-distance power supply
Of course, for distances of more than 500 meters, we also have to consider the problem of decompression when we use the line. So for the monitoring of more than 2 kilometers, how to power the power?
In this case, solar power can be used.
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