ABB ensures power in Swiss tunnels

2017-10-26 - ABB’s products play an important role in tunnel safety, keeping tunnels operational with an uninterrupted power supply to keep the traffic moving smoothly. Two major projects in Switzerland, the N5 tunnel near Neuchâtel, and a temporary substation solution at a highway tunnel in St. Gallen, are electrified by ABB.

The Federal Roads Office, FEDRO, is responsible for maintenance and operation of the national highway network in Switzerland. ABB is providing equipment for the medium- and low-voltage electrical network of two ongoing FEDRO projects. Ensuring a continuous power supply in tunnels is of utmost importance, as it ensures a safe environment where the air ventilation, light and the traffic control system works.

One of FEDRO’s largest ongoing infrastructure projects is the complete renewal of the A5 motorway between Colombier and Cornaux, in the western part of Switzerland. In 2016, the work was started on the last section, between Neuchâtel-Serrières and Saint-Blaise, and the N5 tunnel. The N5 road tunnel is 1.73 km in length and is located near Lake Neuchâtel, which is both an industrial and residential area in the west of Switzerland, at the southern foot of the Jura Mountains. The tunnel was built in 1975 and FEDRO initiated a large-scale project to upgrade the electrical network to meet new regulations.

Another project is the Rosenburg highway tunnel, which is located directly below the St. Gallen city center, the capital of the canton of St. Gallen in eastern Switzerland, with approximately 160,000 inhabitants. Here ABB delivers equipment to a temporary replacement substation solution to replace a substation that suffered damage at the location. The temporary substation, housed in several container modules, is expected to be in service for a while, approximately 7 years while the damaged substation and the 1.43 km long tunnel are refurbished, after 30 years in operation.

To ensure that power is distributed without interruption, ABB offers a wide range of products and technologies to meet the specific needs of the customers. In tunnels, optimizing available space is a key item. Electrical installation always need space to ensure a safe environment for operation and maintenance personnel, but ABB’s compact electrical equipment is frequently in demand for such projects.

At the N5 tunnel, ABB installed the modular medium-voltage UniSec switchgear, which can be scaled easily to accommodate future expansion, and the low-voltage main distribution switchboard Pro E Power. If there is a complete outage from the external power supply, the switchgear switches to the backup line to ensure a continuous power supply. However, as an unexpected power disruption in the tunnel could cause serious problems, ABB has also installed seven UPS (uninterrupted power supply) modules to provide near-instantaneous protection from interruption in input power. To ensure stable energy supply in the tunnel, the automation solution relies on programmable logic controllers (PLC) from the AC500 range and the Relion® protection relays. ABB also provided 20 highly efficient dry distribution transformers from 160 kVA to 2000 kVA.

At the temporary substation in St. Gallen, ABB delivered ZS8.4 medium-voltage switchgear and the low-voltage main distribution switchboard Pro E Power, which are a perfect match for the customer’s requirements. A temporary substation solution of this scale is unusual. Installing the temporary solution, involved closing the highway to traffic to make room for the large cranes needed to lift the containerized substation into place. To cause as little disruption to traffic as possible, the installation was done at night.

Both of these projects are now ongoing. The project in St. Gallen is expected to be completed by the end of the year. The first commissioning of the equipment used in the N5 tunnel project was commissioned in 2016, and the last commissioning is scheduled to take place in 2019.

ABB has a solid track record of electrifying tunnels in Switzerland. For the Gotthard Base Tunnel, which is the world’s longest railroad tunnel, ABB provided the ZX0 medium-voltage switchgear needed to power the tunnel’s infrastructure.