Characterization of a Power-over-Ethernet (PoE)-based LED lighting system

LED lighting systems using Power-over-Ethernet (PoE) technology have been introduced to the lighting market in recent years as a network-connected lighting solution. PoE technology can provide low-voltage direct current (dc) power and control information to LED lighting over a standard Ethernet cable. One of the commonly claimed benefits of the PoEbased lighting system is higher system efficiency compared to traditional line voltage alternating current (ac) systems. This is due to the fact that in the case of PoE systems, the ac-dc power conversion losses are minimized because the acdc power conversion takes place at the PoE switch rather than at all the LED drivers within the lighting fixtures. However, it is well known that power losses can occur as a result of increased voltage drop along the low-voltage cables. The objective of this study was to characterize a PoE lighting system and identify the power losses at the different parts of the system. Based on the findings, we developed a methodology for characterizing the electrical efficiency of a PoEbased LED lighting system and then used this methodology to characterize commercially available PoE-based LED lighting systems and compare their performance. The electrical efficiency characterization included both the system as a whole and each individual component in the systems, such as the power sourcing equipment, powered device, Ethernet cables, and LED driver. The study results also investigated the discrepancy between the measured and reported energy use of the system components.