Fail safe transmission of protection and obstruction signals

The main priority for the new Lötschberg tunnel was safety. Consequently the railway has been fitted with state-of-the-art automation features. This also applies to the energy supply for the whole tunnel facility. The safety-related control signals between the high voltage equipment are transmitted free of malfunctions and in real time using Hirschmann's optical field bus technology .

The safety precautions for the high voltage equipment in the tunnel were very important to protect people and equipment. Therefore the 132 kV and 15 kV rail power supplies have been divided into several segments with isolators, circuit breakers and load switches. The short circuit ampacity of the 15kV catenary chain system is 53,000 A, but for no more than 100 ms.

The switch off systems are designed in such a way that they cut in after 50 ms. The rapid switch off system for the medium voltage network is also fundamental for protecting people because of the high earth leakage current and the pace voltages this causes. Because of the high currents that already occur in normal operation, data is transferred in the foundations of the tunnel
shafts with fibre optic cables that are not sensitive to EMC. In all 355 km of fibre optic cable with up to 144 fibres have been laid.
Areva distance protection equipment exchanges safety-related data using these fibres and Hirschmann fibre optic cable repeaters.

Project parameters

• Tunnel length 34.6 km.
• Maximum train speed 250 km/h
• Maximum tunnel power requirement 62 MW
• Railway power voltages 132 kV / 15 kV
• Catenary voltage 15 kV
• Maximum power consumption per train 2 kA
• Short cirucuit current 53 kA
• Maximum switch off delay 50 ms
• Fibre optic cable length for distance protection equipment 6 km.
• OZD 485 G12 - 1300 54

Solution

• Synchronous proprietary data protocol
• Hirschmann's industrial fibre optic cable converter
• Ring topology along the tunnel shafts
• Protocol independent fibre optic cable repeaters
• Fast ring redundancy
• Inbuilt self monitoring functions