Susceptibility of LED street lamps to voltage dips

Abstract

There is an ongoing transition from high-pressure sodium lamps to LED street lamps that offer higher efficiency, cost saving and better photometric performance. This transition could lead to unintended consequences such as light flicker and extinguishing in street lighting applications when they are exposed to voltage dips. The goal of this paper is to analyse the light intensity variation of various street lamps when they are exposed to voltage dips. Several performance metrics for quantifying immunity of lamps have been proposed. Values for these metrics are obtained by applying artificial voltage dips to lamps. For voltage dips with residual voltage above 38%, lamps are immune in terms of a short-term light flicker metric. For residual voltage above 25%, light intensity reduces but without extinguishing. Compared to an incandescent lamp and high-pressure sodium lamp, LED street lamps exhibit longer zero-light intensity duration. Most of the studied LED street lamps exhibit uncoordinated light intensity drops, i.e. longer or shifted, with respect to the applied voltage dip. Individual characteristics of LED street lamps require testing before installation to prevent unexpected consequences. Recommendations are given for standardisation committees to implement an assessment method for lighting equipment.