System Configuration - Planet Networking & Communication SGS-5220 User Manual

4.16.2 System Configuration

In a power over Ethernet system, operating power is applied from a power source (PSU or -power supply unit) over the LAN
infrastructure to powered devices (PDs), which are connected to ports. Under some conditions, the total output power required
by PDs can exceed the maximum available power provided by the PSU. The system may come with a PSU capable of
supplying less power than the total potential power consumption of all the PoE ports in the system. In order to maintain the
activity of the majority of ports, power management is implemented.
The PSU input power consumption is monitored by measuring voltage and current .The input power consumption is equal to the
system's aggregated power consumption .The power management concept allows all ports to be active and activates additional
ports, as long as the aggregated power of the system is lower than the power level at which additional PDs cannot be
connected .When this value is exceeded, ports will be deactivated, according to user-defined priorities. The power budget is
managed according to the following user-definable parameters: maximum available power, ports priority, maximum allowable
power per port.
Reserved Power determined by
There are five modes for configuring how the ports/PDs may reserve power and when to shut down ports.

Classification mode
In this mode each port automatically determines how much power to reserve according to the class the connected PD
belongs to, and reserves the power accordingly. Four different port classes exist and one for 4, 7, 15.4 and 30.8 watts.
Class Usage
0 Default
1 Optional
2 Optional
3 Optional
4 Optional
1.
2.
Range of maximum power used by the PD
0.44 to 12.95 watts
0.44 to 3.84 watts
3.84 to 6.49 watts
6.49 to 12.95 watts (or to 15.4 watts)
12.95 to 25.50 watts (or to 30.8 watts)
In this mode the Maximum Power fields have no effect.
The PoE chip of PD69012 has been designed to Class level 0 meaning it will be
assigned to 15.4 watts in AF mode and 30.8 watts in AT mode under the power limit
classification. It is hardware limited.
User's Manual of SGS-5220 Series
Classification unimplement
319
Class Description
Very low power
Low power
Mid power
High power