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How Is a Poe Switch Configured? (Part 2)

What is the power supply of PoE? How many devices can be connected, the power is greater than the PoE switch, can you continue to supply power? PoE switches are so expensive, is it safe to buy expensive ones? Your sixth sense is right. In fact, the total power of a PoE switch is a very important indicator, which is directly related to how many cameras can be taken.

To see how many cameras a China PoE Switch for network camera supplies power to, consider: the power supply standard of the PoE switch and the actual power of the PoE switch. There are two power supply standards for standard PoE switches on the market, IEEE802.3af, and IEEE802.3at. The IEEE802.3af standard defines a power supply of 15.4W, and the IEEE802.3at standard defines a power supply of up to 30W. This is because the power supply standard of a single port is different.

The most common camera power on the market is 7W, and you can use af standard PoE switch. If the camera exceeds 16W, you need to use a standard PoE switch. If the camera power is more than 30W, you need to use a dedicated PoE power supply module.

Poe Switch

Poe Switch

In simple terms, if a PoE switch for a network camera is adapted to both af and at power supply standards, its power supply is adaptive.

Let's talk about the total power of the PoE switch.

With the development of power supply technology, at the same time, in the network monitoring, in order to reduce wiring costs and easy and fast use, most engineers will consider using PoE power supply. Taking the PS504E 4-port PoE switch mentioned above as an example, the total power is 60W.

Under the IEEE802.3af standard, it can supply 4 ports (60 / 15.4 = 4), that is, it can power 4 cameras at the same time, that is, full load power. If it is calculated according to IEEE802.3at standard single port maximum power supply 30W, at the same time can only power up to 2 ports (60/30 = 2).

In actual use, the maximum power consumption of many cameras does not exceed 15W. Assuming that each PoE switch port is calculated based on the maximum power (30W), the problem of uneven power distribution may occur.

Don't worry, some PoE switches currently support intelligent power management, which can avoid this situation and make more efficient use of PoE switches for power supply. Assuming that the power of the powered device exceeds 60W, this product can preferentially cut off the power supply of the lower-level ports to ensure continuous power supply to important ports.

In short, 1. Use a switch that supports dynamic power allocation to maximize the power supply efficiency; 2. Understand the maximum power consumption of the powered device, and then divide the total power supply of the PoE switch by the maximum power consumption to get one How many devices a PoE switch can power.