Gamlin, Michael ; Deek, Rany ; Pachin, Juriy ; Müller, Tobias ; Klemm, Marc ; Conde, Sebastian ; Kuntze, Jannis (2023)
A novel discharge resistor design for HVDC cables with high energy content.
11th International Conference on Insulated Power Cables (Jicable'23). Lyon, France (18.06.2023 - 22.06.2023)
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Kurzbeschreibung (Abstract)

A HVDC test system is designed for high DC voltages up to several hundreds of kV and providing moderate DC currents up to several tens of mA. After testing, HVDC cables need to be discharged in a reasonably short time, meaning within a few minutes. In particular, the time during which the cable is tested with a voltage higher than its rated voltage shall be as short as possible. The discharging time of a HVDC cable is simplified calculated by using its time constant τ which is the product of the discharge resistance R and the cable's capacitance C. After the time duration of 5 times τ the HVDC cable is considered as being discharged (99%). The challenge is to combine a fast discharging time of a few minutes while maintaining a low DC leakage current of a few mA or even less during testing. The paper describes a new discharge resistor which is filled with deionised water adjusted to a specific water resistivity. The water resistance can be adjusted in a wide resistance range. The discharge resistor is electrically disconnected during the DC test of the HVDC cable and does not draw any DC leakage current. At the time of the discharging the electrical connection will be established remotely triggered by a radio control either by a whip switch or by a steel stretch band in a pipe. The single discharge resistor can handle discharge energies of up to 60 MJ at 1000 kV DC. Due to the versatile resistor design a parallel connection of up to 3 resistors is possible (180 MJ possible discharge energy). The discharge time of high energy HVDC cables will be less than 5 min.

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