Europe's highest medium-voltage switchgear

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Europe’s highest medium-voltage switchgear

22 MAy 2017

Siemens Schweiz has been contracted by Elektrizitätswerk Zermatt AG to provide the medium-voltage switchgear for Europe’s highest 3S cableway at an altitude of 3'883 metres. The type 8DJH gas-insulated switchgear will ensure the new gondola lift gets an uninterrupted supply of power. 

The construction of the new 3S cableway has also meant reconfiguring the power supply at Matterhorn glacier paradise. Elektrizitätswerk Zermatt manages a 20 kV grid which supplies the village and the surrounding mountains. To operate the network, medium-voltage switchgear units are installed in around 50 substations up in the mountains. These installations have a number of functions: they are used for switching transformers and supply cables and so on, and also give protection in the event of lightning strikes, short circuits, earth leakages or other technical faults. Due to its age and current technical (safety) requirements, the existing medium-voltage switchgear is being replaced by a new version: the 8DJH switchgear made by Siemens AG. This gas-insulated medium-voltage switchgear has been designed for use on secondary distribution public and industrial networks. Its modular concept, extensive range of functions and long-lasting, maintenance-free design meet all the conditions for reliable and economic power supply. The system consists of six control panels (type L power switch) to manage a 20 kV supply. Thanks to its tough mechanical design there is no problem with transporting the system by aerial cableway or helicopter to its destination at almost 4'000 metres above sea level. The switchgear is going to be installed in the new 3S mountain station on the west face of the Matterhorn. The compact design of the SF6 gas-insulated switchgear means it can be used where space is at a premium. The installation altitude of 3883 metres does not pose a problem to the system as an altitude correction factor can be applied to the switch panels at the factory. 

As the 8DJH switchgear is designed to last for 35 years and is completely maintenance-free it will play a significant part in ensuring a fully reliable power supply and safety for operating personnel. And with no maintenance tasks operating costs are also reduced. The addition of relevant modules also allows the switchgear to be integrated into smart grids, so that flexible modern operating concepts can be implemented – for example, on the Klein Matterhorn, the system has a remote control function enabling it to be operated from the control centre in the village or from the home of an on-call service engineer. The unit’s components are fully recyclable and the production process is as environmentally friendly as possible, reflecting the manufacturer’s commitment to a responsible approach to the environment. It will take around two days to remove the old system and install the new one, a job which is scheduled for 2018. The installation of the new 8DJH medium-voltage switchgear at Matterhorn glacier paradise along with the existing equipment on the Jungfraujoch means that both of the highest medium-voltage switchgear units in Europe will have been provided by Siemens.