Increased energy feedback of regenerative braking of swiss high performance locomotives

The amount of energy which is fed back to the overhead contact line thanks to the regenerative braking system of Swiss Federal Railways class Re 6/6 and Re 4/4 II locomotives can be increased with an additional control unit for the tap changer control. A limitation of the brake reactance coils' temperature, realized without a temperature sensor, allows higher braking currents during the descent on long slopes. In multiple command operation the new control system ensures a symmetric charge balance between two locomotives. Therefore, the braking force can now be exploited up to its maximum admissible value. The wear of the mechanical brake shoes of the trains can be significantly reduced. The control system was installed in two test locomotives which now run in regular service. The investments for the installation can be paid back in approximately one year.