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The region's largest power point has been rewired

The official opening ceremony of the new Substation Froloo in Therwil, at which the renovated substation will be presented to the public, takes place on 13 September. In North-West Switzerland, "the region's largest power point" is one of the key hubs between the Swissgrid transmission grid and EBM's and IWB's distribution grids.

Substation Froloo was originally built on the Bruderholz plateau as an open air plant in 1957/58. All lines, isolators, air break switches and transformers were open to the elements and protected by nothing more than a fence.

The new Substation Froloo replaces the old service building and houses all technical systems. EBM, IWB and Swissgrid appointed Alpiq with the design and realisation the new substation. Substation Froloo is one of the key energy feed-in points in North-West Switzerland. The energy from the most distant large power plants is fed from the Swissgrid transmission grid through two 220 kV lines and transformed to lower voltages.

Substation Froloo combines state-of-the-art technology and a compact, extremely safe design. All electrical systems are touch-proof. The building contains several rooms for the switching stations and transformers as well as various safety devices, earth systems, fire alarms and two management systems. Operations at the substation are remote controlled from the grid control centres of the individual electricity providers. The substation was also further reinforced against earthquakes. EBM, IWB and Swissgrid invested a total of around CHF 40 million in the new construction.

EBM and IWB, the two electricity providers from North-West Switzerland, have created a direct access point to Swissgrid's transmission grid in the form of the new substation, providing them with synergies and simplifying various processes.

The existing Substation Bottmingen may be shut down now that the new Substation Froloo has been constructed. At the same time, the surrounding supply network will be adjusted and optimised. All but the 220 kV overland electricity lines are being laid underground. A new liquid soil construction method, which is being applied for the first time in North-West Switzerland, provides a quick and environmentally friendly way of laying the lines. The excavated soil can be re-used after going through a special treatment process.

Substation Froloo and the new underground cables further improve the security of supplies in North-West Switzerland. Power supplies can be re-routed and combined with greater flexibility so that any disruptions to the electricity supply can be fixed quickly.

The Bruderholz local recreational area will benefit doubly once construction has been completed: the majority of lines will disappear from view and the remaining open air plant will be dismantled by the end of 2015 and the 7,000 square metre area regenerated.

History of a substation
Initial construction started during ongoing operations in October 2010. In a first step, the new service building for the indoor substation, containing two transformer rooms, cable basement and a gas-insulated 220/145 kV switching station, was constructed. The assembly of and preparations for the switching station, management units and the new 250 MVA transformer (220/145 kV) continued until 2012. The delivery of the transformer on a heavy goods transporter from Auhafen was a spectacular event. Once it had been successfully started up, the remaining old service buildings were dismantled and additional transformer rooms as well as the switching station for the two 220/145 kV transformers built. The existing, fully functional, 220/145 kV transformer was moved from the open air plant inside the new substation. The dismantling of the old open air switching station and regeneration of the area will be completed by the end of 2015.

Open day, 13 September, 3.00 pm to 6.00 pm
Visitors are welcome to take a look at the new substation from 3.00 pm to 6.00 pm. Engineers will be on hand to explain its functions. Exciting experiments with electricity will give visitors a glimpse into the world of energy. Food and drink are available on site. A shuttle service runs from the BLT car park in Oberwil as no vehicles are allowed near the substation. The BLT car park can be reached by tram 10 and buses 61 and 64 (Hüslimatt stop).


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