Protecting the Channel Tunnel

The Channel Tunnel, when completed, will provide a rail connection between France and England capable of dealing with through passenger and freight trains of the two national railway organisations, SNCF and British Rail, as well as the purpose designed shuttle trains, to be operated by Eurotunnel, for the transportation of motor cars, coaches and heavy goods vehicles. The electric locomotives passing through the tunnels are fed through a 25 kV single phase catenary system rated at 2500 A. In order to operate this unique tunnel rail system, an extensive power distribution system is required to support the requirements of the passenger terminals at Folkestone and Coquelles as well as the auxiliary services of the tunnels, such as ventilation and cooling. To ensure the highest level of security for the power infeed to the tunnel system, the power demand is shared approximately equally between the French and British power systems. The connections to these power systems being at 400 kV, to minimize the effects of unbalance and harmonics, and then transformed to 225 kV for the French infeed and 132 kV for the UK infeed. These grid infeeds supply main high voltage substations on each side of the Channel. It is in these substations where the segregation of traction and auxiliary systems occurs