Photometric Analysis of Filament Type LED Lamp for HPSV Lamp Substitution in Conventional Road Lighting Luminaires

Energy reduction is a great challenge in road lighting applications. Replacing high-pressure sodium vapour (HPSV) with light emitting diode (LED), is a viable approach to reduce energy consumption. However, total replacement can incur a significant capital cost. To reduce the adoption costs, this study aims to investigate the effects towards light distribution of replacing HPSV lamps with filament LED lamps which has similar size and construction. Luminous Intensity Distribution (LID) curve measurement and Luminaire Classification System is used as comparison tools. Both lamps were installed into similar HPSV luminaires to assess photometric performance using goniophotometer measurements. Even though with similar light structure the location of the light output of the lamp caused change in the resulted light output distribution. Evaluation of the LCS diagram shows the luminaire has loss its forward and longitudinal throw of light output and has change to backward and narrow throw. The change is more significant on parabolic reflector of smaller structure. The bowl reflector of the light source and different structure of light output from lamp may have been the cause of this reduction.