Investigations with regard to the influence of the contact screws on the current distribution in a modern screw connector for plastic insulated high voltage

Abstract:
For a safe power supply, it is essential that all components function in a reliable manner and with long-term stability. Current-carrying contacts in power cable sleeves and terminations play a major role in this reliability. In the case of plastic-insulated high-voltage cables, this conducting contact is usually made with the aid of screw connectors. The increasing demand for electrical energy in the course of the German energy change, especially in urban agglomerations, makes it necessary to transmit large amounts of electrical energy over long distances. Due to limited transportable cable lengths, it is necessary to install a large number of cable sections with joints and thus also screw connectors. It is therefore essential to examine the electrical contact in the screw connector more precisely. Among other things, this is important in view of ever increasing conductor cross-sections. In the development of screw connectors, reference is usually made to empirical values. In order to gain an insight into the contact behaviour, it is crucial to better understand the current distribution in the screw connector. The contact screws used in the connector have the tasks of holding the mechanical pull-out forces, as well as generating the initial electrical contact. In order to understand the influence of the contact screws on the current transmission in later operation and what proportion of the electrical current flows through them, screw connectors are investigated by simulation using modern FEM software. The influence of material properties, contact forces, -surface and the position and number of contact screws are considered. The findings obtained in this way provide information on whether the contact screws in their current function carry a significant proportion of the current.