The Reliability Of LED Street Light

A major hurdle to LED acceptance is reliability. This is where standards such as Energy Star come into consideration with strict requirements for light output and expected life expectancy. Compared to high-pressure sodium light that has an estimated life expectance of up to 30,000 hours of expected life, LED lighting supplies 60,000 hours of expected life -- double the lifespan. Because LED lighting technology today offers enhanced light output for a given input power (efficacy) and improved light delivery where it is needed with less light spill or pollution, an energy savings of up to 50 % has been calculated for LEDs compared to existing technologies.

Another reliability concern is that streetlight and industrial lighting luminaires often differ from domestic/consumer-based ‘plug and play’ lighting. Streetlight designs are typically configured with a control unit or power supply at the pole base, and the luminaire remote at the top. These streetlight luminaire sub-assemblies require careful commissioning on site as part of an overall fixture, which introduces potential problems. Electricians typically need to have direct contact with boards, subsystems and connectors during installation. Because of the variety of streetlight luminaire components involved, there are numerous areas where the luminaire can be potentially exposed to stress from the moment of installation.

The first potential problematic issue involves the possibility of miswiring while the LED module is being installed, and miswiring can be as simple as reversing polarity. The luminaire can also be exposed to electrostatic discharge (ESD) that can result from a craftsperson’s handling of the sub-assemblies and while an exposed LED module is being handled before being mounted into the lens fixture. LED luminaire stress can also be the result of sealed enclosures where temperature extremes of -40 °C to 125 °C are not uncommon and can be further exacerbated due to environmental and self-heating conditions.

LED street light applications require the latest robust, small form factor and high-frequency switching inverters to perform power factor correction and precise current control that must operate reliably in the harsh environment of streetlight installations.