Electric-thermal performance of contact elements in high power plug-in connections

High-voltage switchgear requires sliding and plug-in connections with rated continuous currents up to several kiloamperes and rated short-time withstand currents in the range of tens of kiloamperes. In these high power connections, spring loaded contact elements realize the electric and thermal contact of plug and socket. Contact elements transfer the total electric current of the main circuit and, in case they connect a device which dissipates part of its power losses via the main conductors, additionally a directional heat flow. Knowledge of the contact elements' temperature-dependent electric and thermal parameters is required to calculate the temperature distribution in the connection. In the present investigation, a custom-built test rig was used to measure the thermal joint resistance of common contact elements at temperatures up to 180°C by creating a directional heat flow. In parallel, the electric joint resistance was measured. By calculating the ideal electric and thermal flow field with the finite element method, the measured total joint resistance can be separated into bulk and contact portions. As a first approach to calculate contact element temperatures in continuous operation, the obtained parameters were implemented into a thermal network simulation.