The Influence of Peak Current and ECR on the Transmission Performance of High Power Connectors during Faults

Electrical connectors are widely used in industrial environments and for renewable energies. For these purposes, their respective short circuit current carrying capability has to be verified. It is commonly suggested that the thermal stress for contact systems with contact elements is more critical during AC faults than during DC faults because of higher current peaks. Recent findings show the opposite behavior depending on peak current and ECR (electrical contact resistance).This suggests that a deeper look into the effect of current peaks has to be done. This paper explains how the peak current influences the thermal stress for a model contact system during short circuits. The thermal stress is evaluated by numeric calculations and compared to measurements of various load cases. Different types of degradation are linked to the corresponding pulse forms. In contradiction to usual considerations, the transmission performance improves by testing with maximum peak current in some load cases. Therefore AC testing with low peak currents or DC testing can be more critical for contact systems with contact elements. This behavior is highly significant for the dimensioning and type testing of contact systems. Additionally, it is also shown how calculations can predict the short circuit current carrying capability.