ABB overvoltage protection keeps LED street lights on

Lighting currently accounts for nearly 6 percent of global CO2 emissions, generating almost 2 billion tons of the greenhouse gas each year

LED (Light Emitting Diode) technology uses semiconductors to convert electricity into light. LED lighting is much more energy efficient than halogen or incandescent lighting, and also has a significantly longer life span than other types of lighting.

High efficiency, cost-effectiveness, long service and reduced maintenance make LED lighting systems a very attractive option for municipalities, which typically spend more than half their budgets on lighting for public areas. LEDs are also easily controllable in terms of duration and level of illumination.

However, unlike mercury-vapor lamps, LED lighting systems (which includes control components such as LED drivers) are designed for low operating voltages only, and are therefore very sensitive to transient overvoltages. In fact, without proper surge protection an LED system is unlikely to survive an overvoltage, and even if it does, may sustain damage that will shorten its lifetime.

Overvoltages from lightning strikes are one of the most common natural causes of power interruption, creating power surges in the range of hundreds of kilovolts (kV), which is enough to blow fuses, damage sensitive electrical equipment and even cause blackouts in nearby areas.

LED vulnerability

Power surges can also result from switching operations, earth faults, short circuits or tripping fuses originating industrially. For example, if a large machine that uses lots of electrical power to operate suddenly switches off, the sudden drop in power use could affect unprotected LED lighting systems attached to the network.

Since LED lighting is usually connected to the network with long cables, any disturbance phenomenon is amplified through the line. Despite this vulnerability, ABB has a new surge protection device designed specifically for LED lighting applications.

For more than 80 years, ABB has designed and manufactured lightning protection systems to shield buildings from the effects of direct lightning strikes, and also surge protection devices to guard indoor electrical and electronic equipment.

This offering now includes complete solutions for LED lighting systems. It is a compact surge protection device (SPD) featuring DIN rail mounting that is prewired for easy installation in small power supply boxes (lamp post enclosures, traffic lights, parking lots, bus shelters, billboards, decorative lighting, etc).

Installation in lamp post enclosures prevents service interruptions, damage, and constant lamp replacements, which are difficult to access without proper equipment, like cradle lifts.

A circuit breaker or fuse holder serves as back-up protection to ensure priority to system safety and continuity of service. In addition, ABB’s SPD is equipped with a safety reserve to protect the lighting system even after a first high transient overvoltage strike.

Overall network lightning protection

The device is bottom-wired with a 17-cm long prewired cable (line and neutral) that enables easier installation to the terminal block of the power enclosure. The earth has to be connected. The bottom wiring design prevents condensation problems, and is rated IP32.

Promoting a preventive approach, ABB has joined forces with main market players such as lighting appliance manufacturers, fitters and lighting unions, etc., to propose a full range of surge protective devices to be installed at various points of the network.

From the switchboard to the lamp post, SPDs offer protection and continuity of equipment service for indoor/outdoor lighting in public and private areas (streets, parking lots); street furniture (bus shelters, billboards, decorative lighting); light poles to ensure road traffic safety.

Generally, public lighting equipment is powered with a TT or TN-S neutral point system, so if struck by lightning, transient overvoltages may be transmitted via earth cables. This can happen either by a direct strike on the metal conductor mast, in which the energy travels to the ground; or by an indirect strike, in which the lightning strikes an object near the system, or directly hits the ground.

Earth connections transmit transient overvoltages via power cables, reaching the most sensitive components. To protect public lighting, ABB recommends installing SPDs (Type 2) in switchboards supplying the lamp poles, traffic lights or street furniture; and SPDs (Type 2+3) as close as possible to sensitive systems, in the power supply cabinets of the lamp pole masts.

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About the author

Bertrand Berges

After completing my bachelor’s degree in electrical and electronics engineering at the University of Hertfordshire, I joined ABB in 1999 as technical support for the AF contactor range. From 2009 until 2016 I was manager of Surge and Lightning Product Marketing. The opportunity to deal with natural phenomena adds a special spark to my engineering job. I am now Segment Marketing Manager for Rail, Marine and Food and Beverage segments. Always looking for new solutions to benefits our end customer’s needs.
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