Hybrid masts as wooden replacement masts

At the beginning of January 2018, the Burglind storm swept across large parts of Europe. In the southern Black Forest, there is a power outage due to overturned overhead lines. The destroyed wooden poles will be replaced by hybrid poles from FUCHS Europoles.

Masts for Baden-Württemberg and Switzerland

The Deutsch-Schweizerische Holding Energiedienst AG supplies large parts of Baden-Württemberg and Switzerland with electricity. The German network operator ED Netze, part of the group, has been a customer of FUCHS Europoles for more than ten years and orders several hundred hybrid poles every year. At the beginning of 2018, due to the storm in the Black Forest, numerous fallen or broken wooden poles had to be replaced unscheduled.

Power breakdown due to the storm "Burglind"

Dirk Umland, line team leader at ED Netze, sends photos from a location “where the Burglind storm flattened ten wooden poles over a distance of one kilometer. Only the wooden replacement mast that was replaced two years ago remained standing.” The well-known domino effect occurred with the wooden masts. A fallen mast took the next one with it. Only the much more stable hybrid mast from FUCHS Europoles put an end to this. In total, Burglind caused more than 60 medium-voltage faults in the southern Black Forest. Within two weeks, 15 wooden replacement masts for broken wooden masts were installed in the area south-east of the Feldberg. The affected towns were back on the grid a few hours later, but anyway:"If only replacement wooden masts had been installed, we would not have had a breakdown," says Umland, an expert.

Big mission

"We deliver between 600 and 800 masts to the energy service every year," estimates the sales staff in the office and field service of the energy division of FUCHS Europoles. The old wooden masts, which after around 40 years are either rotten or can no longer withstand extreme storm events, are gradually being replaced.

Hybrid – practical and stable

As a long-standing customer, Energiedienst was one of the first to learn about the new wooden replacement masts that the Neumarkt-based company was launching in 2008 in two versions: one as a solid steel wall mast and the other as a hybrid mast. Its lower part is made of hot-dip galvanized steel and the upper part, each three meters long, is made of glass-fibre reinforced plastic (GRP).
A number of hybrid masts are being tested in a pilot project – and are convincing. Among other things, the Black Forest company is impressed by the drilling of the three-meter-long GRP upper parts directly on site, individually tailored to the trusses used. But also the low weight of the GRP mast section, because it can be carried by hand with a few people if necessary. From this point in time, only the hybrid pylons are used by the Baden energy supplier as replacement wooden pylons for the medium-voltage lines.

Hybrid or steel – depending on the truss

Energy suppliers such as Energiedienst, who use arch supports or triangular trusses in addition to single-level trusses, work very well with the hybrid masts, since the GRP upper part can be drilled directly on site to match the truss before it is then flanged onto the steel lower part and the truss is mounted. Bird protection covers are not necessary with the non-conductive plastic version.
Other energy suppliers switch to the one-level traverse and then use the slightly cheaper solid steel masts from FUCHS Europoles. In these cases, the steel masts are pre-drilled at the factory so that only the traverse needs to be mounted on site. Advantage: The customer can order masts plus traverses from FUCHS Europoles as a complete package.

Stable, light, durable – good substitute for wood

Otherwise, both mast types – steel or hybrid – are identical in terms of durability and stability and can also carry the same payloads. At FUCHS Europoles, the demand for hybrid and solid steel poles is roughly balanced.

The wooden replacement masts also impress with their slimness and low weight. A hybrid mast at a height of ten meters weighs around 160 kilograms, twelve meters weigh around 220 kilograms. The corresponding weights for steel are somewhat higher, at 220 kilograms (10 m) and 250 kilograms (12 m) respectively.

In any case, the energy suppliers save themselves having to inspect the routes, which is necessary every two to five years with the old wooden masts. With hybrid masts, this is only necessary every 20 to 25 years, when the trusses, cables and insulators are checked at regular intervals.

Set new locations

The hybrid masts are usually placed in the holes in the old wooden masts to protect existing structures. However, if a stability check reveals that a large part of the wooden masts on a route are defective and need to be replaced, it sometimes makes sense to completely replan the route. Because: Since the wooden replacement masts can carry a much higher payload than the conventional wooden masts, you need fewer masts on the same route. This is advantageous for some farmers because they can at least partially move the new mast locations from the middle of the field to the edge of the field; Destruction or soil compaction of the usable areas by heavy equipment are a thing of the past. It is even worthwhile to have the easement changed.

Slim lightweights for Scandinavia

FUCHS Europoles is now also successful abroad with hybrid poles. The Scandinavian countries are particularly interested: Here, too, both the ecological advantages – no environmentally harmful wood preservatives have to be used – and the economic advantages – e.g. stability and longevity even in adverse weather conditions, easy foundation even on rock – pay off of the wood substitute materials steel and GRP the end.

Specifications

Location: Black Forest, Baden-Württemberg
Execution period: February 2018
Scope:

  • 15 wooden replacement poles (hybrid)
  • Customer: ED Netze GmbH
  • Material: solid steel wall base; hot-dip galvanized upper part
  • Height: 12 to 15 meters
  • Diameter at the base: 267 – 302 mm
  • Mast: octagonal conical; cement gray coated (RAL 7033)
  • Foundation: concrete-free; 1/6 of the mast length