Skip to main content

Medium-voltage Systems
in Tunnel Construction

From the lighting to the ventilation, the electricity supply in tunnel systems has particular demands on shape, function and design.
We have the right solution for your tunnel project as well as references that wholly corroborate our expertise. 

Medium-voltage Systems Providing Electricity to Tunnel Systems

Tunnel Transformer Stations: safe, long-lasting, flexible, automated 

Some of the important requirements of medium-voltage systems in tunnel construction are:

  • SF6-free
  • compact
  • safe and protected in case of fire
  • use of reliable insulating material
  • cost effective possibilities for automation
  • quick and flexible replacement in case of failure.

We listen to your specifications and can offer you the perfect solution to meet all your requirements.

In certain regions / counties there are fundamentally different specifications around the build and implementation of compact transformer stations in tunnel systems.

The following topics and questions are found on most specification checklists:


  • is space limited or can space be made for more systems by upgrading to a more compact medium-voltage system? In this case, compactness would be a deciding factor.
  • is the use of SF6-systems permitted by the operator and is this, without a doubt, the most cost-effective solution? If not, SF6-free systems should be considered.
  • Air-insulated units can be installed, if there is enough space, however you have to take on board the negative effects that pollution and corrosion with have on the primary component over the years.

Fire Safety

  • as is well known, a fire in a tunnel cannot be excluded whether it be in the tunnels themselves or in the system rooms.
  • therefore particular attention should be paid to electrical insulating materials
  • how would the solid insulation material of components behave in the case of a fire? What type of liquid is used in transformers and systems? What happens if the SF6-systems cause a fire with gas?

Water Penetration, Damp

  • it is recommended to install systems whereby the whole primary part is encased in IP67, such as the ECOS-C, if the systems should remain up and running in case of flooding
  • should the insulation capability remain the same even in high air humidity, which is trickier with air-insulated systems, unless this is taken into account when interpreting voltage strength.

Speedy Service or Incident Management

This is most effectively managed with local distributors who construct systems in Switzerland and/or who have replacement systems «in stock».

  • incidents are best resolved by replacing the damaged system with an identical, factory-assembled system that has been tested in-house and can be installed very swiftly.
  • getting the necessary installation service and competence in safety and control, all from one provider is ideal and is a fact that should be considered when choosing suppliers.

We can offer you the perfect solution to meet your specific requirements.


Markus Keusch
Project Manager Large Projects / Tunnel Construction
+41 79 681 63 64


Other solutions