Lab : Compare energy consumption between POE and direct power supply

Objective: The objective of this topic is to compare the results of energy consumption measurements of different POE devices, in our case a Cisco POE switch, a sensor and a light, using power meter and Raritan. For each type of measurement we used 3 different topologies. First one was connecting POE device directly to meter/Raritan (figure 1). Second was connecting Cisco Power Injector to the meter/Raritan and the POE devices to PI (figure 2). The last was connecting 2960 switch to meter and POEs with the switch (figure 3).

  Direct measuringUsing Cisco Power Injector





Figure1 Direct measuring                                        Figure 2. Using Cisco Power Injector

Using POE Cisco 2960 switch and power meter

Figure 3. Using POE Cisco 2960 switch and power meter

Results: The results show that an equipement powered by POE consumes more than when it uses a direct power supply. We conclude that POE equipement is not green. However, the interest of POE technology is to be able to remote control its power. Procedures can be then developed to automatically power off POE equipment when it is unused.