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Figure 10-3 Principle of centralized power supply
There are two paths for the power output of CAM4: Return path 1 and return path 2. Reflow 2 first
flows to CAM1, and then flows to the power supply from power supply ground of CAM1. In this
way, the reflow of power supply ground CAM4 affects the video ground of CAM1, resulting in
interference stripes on the screen. And CAM4 also interferes with CAM2 and CAM3.
In the same way, CAM1, CAM2 or CAM3 affects other cameras besides itself.
The main reason for the interference of centralized power supply is that the power supply ground
of camera is not isolated. To solve this problem: Use dual-power devices with isolation of power
supply ground; equip low-power devices with power isolators to block the return path 2 low-power
devices can also use power isolators to block the return path 2; use isolated power supplies for each
channel, or power the device separately, which are the two recommended methods.
10.5 Connector Waterproof Protection
HDCVI cameras need to be well waterproofed and protected. After installation, wrap the BNC
connector and power connector tightly with insulated or waterproofed tape to prevent water and
external electromotive forces. When metal casing device is installed on metal surfaces such as
elevators and buses, the metal casing should not be in contact with the installation surface to
prevent water and external electromotive forces.
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