Lightning induced voltage on control cable in traction substation

An electronic circuit in a control panel installed in a substation for Japanese bullet train (Shinkansen) was damaged due to a lightning. A field test is carried out to clarify the cause of the failure. The results show that a voltage is induced on a control cable for a earthing system and its amplitude exceeds the lightning withstand voltage of the control circuit. The effect of an earthing of an unused core in the control cable is investigated at a traction substation. To reduce the induced voltage, the unused core has to be earthed at the end of the control panel. If the core is earthed at the other side, a high voltage appears at the control panel. The effect of the lightning surge waveform on the induced voltage is also discussed. These results are effective for a proposal of a countermeasure to the fault and insulation design of traction substations.