Hybrid masts in the Black Forest

proven to be ecological and economical

In early January 2018, the Burglind stormy depression swept over large swaths of Europe. In the southern part of the Black Forest, downed power lines resulted in local power outages. The destroyed wooden masts have been replaced by FUCHS Europoles hybrid masts.

Poles for Baden-Wuerttemberg/Germany and Switzerland

The German-Swiss holding Energiedienst AG supplies large portions of Baden-Württemberg and Switzerland with power. One part of the Group, German network operator ED Netze, has been a customer of FUCHS Europoles for more than ten years and orders several hundred hybrid masts each year. In early 2018, numerous wooden masts that had fallen or broken off due to the stormy depression in the Black Forest needed to be replaced unexpectedly as well.

Power failure from the Burglind stormy depression

Dirk Umland, power line team leader at ED Netze, sent pictures from one location “where the Burglind storm knocked down ten wooden masts along a one-kilometre stretch. Only the wood substitute mast that was replaced two years ago remained standing.” The wooden masts fell victim to the well-known domino effect: When one mast fell over, it took down the next. It was only the much sturdier hybrid mast from FUCHS Europoles that put an end to it. All in all, Burglind caused more than 60 medium voltage failures in the southern part of the Black Forest; within two weeks, 15 wood substitute masts were installed to replace broken wooden masts in the area south-east of the Feldberg mountain. While the communities affected were back on the network within a few hours, expert Umland is sure of one thing: “If only wood substitute masts had been installed, we would not have had any power failure at all.”

Large order

“We provide Energiedienst with between 600 and 800 masts each year”, sales worker estimate, in the back office and on the sales force of the Energy Division of FUCHS Europoles. In this way, the wooden masts – which are either rotten or no longer able to withstand extreme storm events after some 40 years – are being successively replaced.

Hybrid – practical and sturdy

As a long-time customer, Energiedienst was one of the first to learn about the new wood substitute masts, which the Neumarkt company launched on the market in 2008 in two versions: solid-wall steel poles on the one hand and hybrid masts on the other. The lower section is made of galvanized steel and the three-metre long upper section of glass fibre reinforced plastic (FRP).

A few hybrid masts were tested in a pilot project – and were convincing. One thing that impressed the Black Forest company was that the three-metre-long FRP upper sections were drilled directly on site and tailored perfectly to the cross arms being used; another was the fact that the FRP mast sections are so lightweight. They can be carried by hand with only a few men in a pinch. From that time on, only the hybrid masts have been used by the energy provider in Baden-Württemberg as wood substitute masts for medium-voltage lines.

Hybrid or steel – depending on the cross arm

Energy providers like Energiedienst which also use arch supports or triangular cross arms along with level cross arms have had very positive experiences with the hybrid masts, since the FRP upper section can be drilled directly on site to match the cross beam before being mounted onto the steel lower section, after which the cross arm is attached on top. Bird protection covers are not necessary for the non-conductive plastic version.

Other energy providers are changing over to the level cross arm and exclusively use the somewhat more economical steel solid-wall masts from FUCHS Europoles. In these cases, the steel masts are pre-drilled in the factory so that only the cross arm still needs to be attached on site. Advantage: The customer can order the masts and cross arms from FUCHS Europoles as a complete package.

Sturdy, light, durable – a good substitute for wood

Otherwise, both mast types – steel and hybrid – are identical with regard to both their durability as well as their sturdiness, and they also have the same carrying capacities. On the whole, the demand for hybrid and steel solid-wall masts is roughly balanced at FUCHS Europoles.

The wood substitute masts are also convincing thanks to their slenderness and low weight. Overall, a ten-metre-tall hybrid mast weighs around 160 kilogrammes, with twelve metres weighing in at around 220 kilogrammes. For steel, the corresponding weights are somewhat higher: 220 kilogrammes (10 m) and 250 kilogrammes (12 m).

In any case, the energy providers are spared the need to inspect the lines, which is necessary every two to five years with the old wooden masts. With the hybrid masts, this only has to be done every 20 to 25 years – and at the same time when the cross arms are normally checked along with the lines and insulators.

Determining new locations

To conserve the existing conditions, hybrid masts are usually placed in the holes bored for the old wooden masts. However, if it is determined when checking the structural stability that a large portion of the wooden masts is defective and needs to be replaced, it sometimes makes sense to completely redesign the line. The reason for this is that, since the wood substitute masts have a much higher carrying capacity than the conventional wooden masts, fewer masts are needed for the same line. This is beneficial for some farmers, since at least some of the new mast locations can be moved from the middle of a field to the edge; the destruction of usable areas or soil compaction due to heavy equipment will therefore be a thing of the past. For this reason, it is actually worthwhile to have the easement changed.

Slender, lightweight poles for Scandinavia

Meanwhile, FUCHS Europoles has become successful with its hybrid masts in other countries as well. Mainly the Scandinavian countries are interested: Both the ecological (no environmentally harmful wood preservatives need to be used) and economic advantages (such as sturdiness and longevity, even in unfavourable weather conditions; simple footing, even on rock) of the steel and FRP wood substitute materials pay off here.

Technical Details


Customer

ED Netze GmbH


Project term

January 2018


Scope of delivery

15 wood substitute masts (hybrid)


Details

  • Material: lower section steel solid-wall, galvanised; upper section: FRP
  • Height: 12-15 m
  • Diameter of foot: 302-267 mm; head: 168 mm
  • Mast: conical octagon; coated with a cement grey colour (RAL 7033)
  • Footing: concrete-free, 1/6 of the mast length 

Further information

Links

Overhead transmission poles

Overhead transmission poles