The total power of POE switch is a very important index. It is directly related to how many cameras can be powered. For a POE switch with 400W power supply and 24 ports, the total power is about 370W after subtracting the loss.
Under the POE 802.3 AF standard, POE switch can supply 24 ports (370/15.4=24), which means it can supply power to 24 cameras at the same time, that is, full power supply. However, if it is calculated according to the maximum power supply of 30W per port under POE 802.3 AT standard, only 12 ports can be supplied at the same time (370/30=12).
In actual use, the maximum power consumption of many common webcams is basically less than 15 W. If each POE port reserves the power supply according to the maximum power (for example, 30W), there will be cases where some ports cannot run out of PoE power, but some ports cannot get enough power. For example, some POE switches support dynamic power allocation, which can solve the problem of uneven power allocation. When purchasing a POE switch, you should consider whether the switch supports dynamic power allocation, so that each port gets the power it actually uses, achieving efficient utilization of the power supply of POE switch.
Technical advantages of POE
1. Simplified wiring and cost saving
Many live devices, such as surveillance cameras, need to be installed in places where it is difficult to install AC power supply. POE makes it unnecessary to use expensive power supply. It saves the costs and the time spent on installing power supply.
2. Convenient remote management
Like data transmission, POE can supervise and control the device by using Simple Network Management Protocol (SNMP), which can provide functions such as night shutdown and remote restart.
3. Safety and reliability
POE power supply equipment will only supply power to the equipment that needs power supply. Only when the equipment that needs power supply is connected, there will be voltage in the Ethernet cables, thus eliminating the risk of electric leakage. Users can safely mix existing devices and POE devices on the network. These devices can coexist with existing Ethernet cables.