Electrical Power & Protection


Lightning and surge protection for ­highway gantry signs

November 2015 Electrical Power & Protection

Highway gantry signs are used to hold traffic-specific detection systems such as CCTV cameras, induction loops and radar detectors. On toll roads, additional detection devices are installed which ensure fully automated toll data identification.

To prevent a direct lightning strike to the display modules, it is advisable to install an isolated lightning protection system which is directly fixed on the structure by means of air-termination rods and isolated spacers, or a patented high voltage resistant and insulated HVI conductor. Thus, flashover of lightning currents to the components of the highway gantry sign is eliminated.

The highway gantry sign profile between the carriageways is earthed via radial earth electrodes or earth rods, such as those made of stainless steel. The power and control cables between the control cabinet and the gantry sign are protected against lightning strikes by a buried conductor, also potentially stainless steel. This is the second earth-­termination system of the highway gantry sign. In South Africa, stainless steel is a viable alternative to copper, given the high theft rate of copper in the country.

In the control cabinet, direct equipotential bonding is established and the required surge protective devices are installed. In principle, all unshielded and unearthed cables must be protected by surge protective devices. The low-voltage supply of the roadside controller is protected by a lightning current carrying combined arrester, for example DEHNventil M TT 255 (FM). The information technology cables of the roadside controller are typically connected to the traffic control centre via optical fibre cables. In this context, it must be ensured that their metal sheaths are ­connected to the equipotential bonding system.

For more information contact Alexis Barwise, Dehn Africa, +27 (0)11 704 1487, [email protected], www.dehn-africa.com



Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Power supply with scalability optimised
Schneider Electric South Africa Electrical Power & Protection
Schneider Electric has introduced the Easy UPS 3-Phase Modular to the South African marketplace. This robust uninterruptible power supply (UPS) is designed to protect critical loads while offering third-party verified Live Swap functionality.

Read more...
Prioritising arc flash safety
Comtest Electrical Power & Protection
Comtest has developed a range of thermal imaging and wireless testing tools from Fluke, designed to ensure safety is the top priority for engineers working in potentially dangerous arc flash zones.

Read more...
Hot Dip Galvanizers Association shines new light on renewable energy
Electrical Power & Protection
The Hot Dip Galvanizers Association of Southern Africa plays an important role in supporting the energy value chain – which spans clean, renewable and green energy – as it powers towards key sustainability targets.

Read more...
ACTOM supplies high-voltage equipment to wind farm project
ACTOM Electrical Machines Electrical Power & Protection
ACTOM High Voltage Equipment is currently in the process of manufacturing 400 kV and 132 kV high-voltage primary equipment for the Ummbila Emoyeni wind farm project in Mpumalanga.

Read more...
Energy measurement module for BL20 I/O System
Turck Banner Southern Africa Electrical Power & Protection
Turck’s BL20 energy measurement module enables precise monitoring of the energy consumption of single- or three-phase systems.

Read more...
Distributed energy resource management systems: a grid symphony
Schneider Electric South Africa Electrical Power & Protection
To listen to a symphony is one of the world’s great gifts. A conductor must ensure that instruments play beautifully as a whole and are kind to the ear and uplifting to the spirit yet shine in their individuality. The same can be said of a DERMS, which must effectively manage diverse energy sources to avoid compromising the grid’s integrity.

Read more...
Focus on energy sector infrastructure development can drive economic growth
Electrical Power & Protection
Post-election periods in South Africa often see a renewed focus on infrastructure development, with a specific emphasis on directing investments towards the energy sector. This strategic approach aims to accelerate economic growth, address energy challenges, and ultimately uplift the overall standard of living for the populace.

Read more...
Turning the continent into a global leader for green fuel
Electrical Power & Protection
Africa is at a turning point, with the potential to shift from being a supplier of raw materials to becoming a leader in advanced manufacturing, particularly in the growing green hydrogen market. For this transformation to happen, African countries must work together, combining their resources and talents to build a strong local economy.

Read more...
Epiroc showcases battery-electric drill rig at MINExpo 2024
Electrical Power & Protection
Epiroc recently showcased a demonstrator of the first ever Down-The-Hole SmartROC D65 battery-electric drill rig at the MINExpo exhibition in Las Vegas.

Read more...
Smart metering for utility management and sustainability
Electrical Power & Protection
Theodore Paraskevakos, a Greek-American inventor and businessman, developed the first smart meters in 1972 while collaborating with Boeing. Since then, smart meters have evolved significantly.

Read more...