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Many customers are consulting POE switches. They are more concerned about how many surveillance cameras can be connected to a POE switch. After reading this article, you are so smart that you will not be able to beat you!
To understand how many cameras can be connected to the POE switch at the same time, look at three aspects : POE switch power supply standard, total power supply of the POE switch, and the code stream of the camera. Let's talk about these aspects in the system!
1, POE switch power supply standard
There are two standards for popular POE switches in the market. IEEE802.3AF and IEEE802.3 AT define the power supply of 15.4W and 30W respectively. However, due to the loss during transmission, the actual power supply is 12.95W and 25.5W. .
When using a POE switch that supports the IEEE802.3af standard, the power of the powered device cannot exceed 12.95W. When the POE switch of the IEEE802.3at standard is used in the same way, the power of the powered device cannot exceed 25.5W.
Generally, a POE switch that supports the IEEE802.3AF/AT standard at the same time, the power supply is adaptive. For example, it is connected to a 5W device, which provides 5W of power; if it is connected to a 20W device, it provides 20W of power.
2, the total power supply of the POE switch
This can be judged from the total power of the POE switch. Under the IEEE802.3AF standard, if the total power of a POE power supply of a 24-port POE switch reaches 370W, then it can supply 24 ports (370/15.4=24), but if it is a single port according to the IEEE802.3AT standard, the maximum is The power supply is calculated at 30W, and at the same time, only 12 ports can be powered (370/30=12).
For example, an 8-port POE switch supports the IEEE802.3AF/AT standard. The power of a single camera is 11W. Then the switch can connect 8 such cameras. If the power of a single camera is 20W, one or two ports are reserved. Suitable, it is recommended to connect 5-6 cameras.
3, the camera's code stream
If the power supply from the POE switch is inaccurate, since the network monitoring requires high definition and smoothness, it depends on the code stream of the camera. After all, the POE switch not only supplies power but also transmits video data.
The code stream of common cameras: 720P (1 million pixels) code stream is 4.5M, 960P (1.3 million pixels) code stream is 6M, 1080P (2 million pixels) code stream is 8M, 3 million pixel code stream is 10M, 500 The megapixel code stream is 13-15M.
When transmitting video data, the actual bandwidth utilization of the POE switch is only about 60%.
For example, an 8-port POE switch, the port transmission rate is 100 megabits, the camera is 720P, how many such cameras can be connected?
The camera stream of 720P is 4.5M. The available bandwidth of this POE switch is about 60Mbps, and about 60/4.5 is about 13. Since the PoE switch has only 8 POE power ports, it can be fully loaded.
Similarly, if the 8-port 100-megabit POE switch is connected to a 1080P camera, then only up to seven such cameras can be connected.
When actually using a POE switch, it is necessary to consider both the power supply and the camera code stream, and the two must be satisfied before they can be used safely and smoothly.
POE typical application diagram: