Thermal behavior of energy-efficient substation connectors

The contact resistance is the key variable that characterizes the stable performance and long-term service of an electrical connection. It is worth noting that the contact resistance in substation connectors can be several times that of the connector's resistance. To reduce connection losses and thus decrease connector's operating temperature, it is important to minimize contact resistance. The aim of this work is to characterize the relationship between the surface preparation, the resulting contact resistance and the thermal performance of substation connectors. First, the thermal behavior of substation connectors assembled with the traditional and a new installation method proposed by the authors has been characterized. It has been done by means of experimental temperature rise test and current cycle test. Thanks to these results, it has been proved that the new installation procedure allows reducing connector's temperature in operating conditions as well as the variability of the electrical resistance among different samples due to thermal stress. Moreover, by means of experimental measurements, the temperature dependence of the contact resistance has been analyzed, with the objective to characterize the performance of an electrical contact under different operating temperatures. To determine the temperature coefficient of the contact resistance, an experimental resistance measurement has been continuously performed during the cooling of a contact interface, previously heated at 200 °C. This value can be very useful for an optimal design of the substation connectors.