Basic investigations on joints with cylindrical aluminum conductors made by press- and shrink-fit for high-current devices

Electrical joints with cylindrical aluminum conductors are often used in Gas Insulated Switchgears (GIS) and Gas Insulated Lines (GIL). Separable connections have to be used for dealing with relative movement between the conductor and the encapsulation initiated by thermal expansion on one end of the conductor. On the other end of the conductor permanent connections can be used with the intention to reduce the costs and operating power losses. Therefore, technologies like the press- and the shrink-fit are suitable. In order to use those technologies for electrical joints proper joining parameters have to be determined from baseline investigations and the long-term behavior of the joints has to be investigated. This paper presents and compares these two joining technologies, press- and shrink-fit. Joints are made with both technologies and the influence of different parameters like surface properties and forms on the joint resistance are being investigated. The behavior of the joint resistance over time is determined from oven-experiments at a temperature of 105 °C. Furthermore a comparison between the cylindrical contacting of the shrink-fit and the flat contacting like it can be found at bus bar joints is made with focus on the contact resistance.