Calculation of Damping Coil Parameters to Limit the Short Circuit Current in Rectifier Stations

Abstract:
The dc feeding is suitable for traction power in cities or near-distance railway services. To energize the overhead lines or the third rails, rectifier stations are installed at certain distances, usually at 3 km to 5 km intervals. All necessary electrical and control components are equipped in these stations to provide secure energy and protect the system against failures like short circuits or overloads. In the case of a short circuit in the rectifier frame, a relay is engaged to protect the panel from damage. But the relay also has its own current carrying capacity limits for a certain time. Depending on how many rectifiers are connected in the panel, the short circuit current might be much higher than the relay capacity. That is why, a damping coil is conceived so that the short circuit current is kept within the operational limit of the relay. This paper deals with the calculation of the inductance of the damping coil. The simulation results are presented to investigate various scenarios like rectifier short circuits and protection.