Osram safeguards LED road luminaires with high overvoltage protection

The power consumption benefits from LED street lighting could be compromised by the threat of voltage peaks from lightning strikes.

Lightning density in Europe differs significantly from region to region. Mandatory image source specification: © British Crown copyright 2015, the Met Office

Cities like Milan and Turin are expecting at least 50 percent less electricity consumption thanks to recent transformations to LED and Optotronic control devices from Osram. However, lightning strikes can risk the economic advantages as LED modules run with lower voltage levels and could be damaged from overvoltage.  This danger has increased with the UN Climate Council identifying increasing levels of lightning worldwide in its fifth assessment report (IPCC14).  Around 10 percent of the several million lightning strikes occurring each day impact on the ground, thereby causing voltage peaks. To effectively protect LED modules assembled in road luminaires, the Osram Optotronic 4DIM features overvoltage protection of 8 kilovolts as standard.

Levels of lightning density in Europe are high in summer, particularly in July and August, and with large regional differences – the U.K. Meteorological Office recorded between just 0.25 and over 20 strikes per square kilometre in 2014. In general it can also be said about distribution across Europe that lightning in the South East occurs more frequently than in the North or North West, and in towns and cities more than in rural areas
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As a consequence, the new generation of Osram “Optotronic 4DIM” electronic control units feature protection of up to 8 kilovolts between mains supply and ground in protection classes I and II. This means that lightning can strike an area of up to 200 metres from a luminaire mast without the LED module being damaged.

Compared to the common 4 kilovolt overvoltage protection with control units of other manufacturers, this means that with an example mast spacing of 30 metres, twice the quantity of road luminaires survive lightning impacts without damage. In many European regions the high level of overvoltage protection with Optotronic 4DIM units is usually sufficient to provide long term protection. However in regions with high lightning density levels though, it is recommended as a precaution to implement supplementary protective measures, for example in the main distribution frames and junction boxes of road lighting systems.

Osram as the first manufacturer made this 8 kilovolt protection possible with a so-called EQUI connection (equipotential) for protection class II applications, enabling various components of the lighting system to exhibit the same electric potential, thus significantly reducing the occurrence of overvoltage on the LED module.

Optotronic control units also reliably protected from voltage peaks from two other hazardous sources: – those with up to 6 kilovolts due to load changes or switching commands in the power supply grid (often generated several dozens of times per year), and from electrostatic discharge (ESD) occurring with for example maintenance work, if no ESD protective measures exist.

Overvoltage though does not automatically mean the immediate failure of an LED module, but can cause premature ageing and therefore shorter operating periods; this has consequences for the operator in terms of costs. Normally, LED solutions have low failure rates and achieve up to 100,000 operating hours.

Novel Energy Lighting supplies all Osram LED products. Talk to us today about your requirements for LED lighting, and LED street lighting. Tel: 0208-540-8287, Email: sales@novelenergylighting.com