According to the definition of 802.3af/at standard, Poe power supply system includes two kinds of equipment: PSE and PD. The typical equipment application network diagram is as follows.
(1) Definition of PSE equipment:
PSE (power sourcing equipment) is mainly used to supply power to other equipment,
(2) Classification of PSE equipment:
It can be divided into two types,
Midspan device: Poe function is outside the switch or other network devices;
Endpoint devices: Poe functions are integrated into switches or other network devices.
(1) Definition of PD equipment:
PD (powered device), the device used to receive power in Poe power supply system.
(2) Type of PD equipment:
Wireless AP equipment;
Camera; some low-power SOHO switches choose pulse network filter
3. Power supply mode:
At the same time, the 802.3af/at standard also defines PI (power interface: the interface between PSE / PD and network cable).
(1) Classification of PI:
Alternative a: network cable 12 and 36 pairs of power supply, i.e. signal line power supply;
Alternative B: 45 and 78 pairs of network lines are used for power supply, i.e. idle line is used for power supply.
(2) Safety / reliability description of Poe power supply:
Because the DC current and data frequency do not interfere with each other, the micro network communication transformer can transmit current and data at the same time on the same pair of lines. In fact, the price of the micro network transformer, the micro Ethernet RJ45 connector, can be regarded as a kind of "multiplexing" for the cable.
The voltage provided by Poe is below 57V, which belongs to "safe voltage". The price of pulse network filter purchased meets the requirements of safety regulations.
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