The majority of power cables these days are extruded XLPE-insulated types. These cables consist of a conductor, an inner conductive layer, the main insulation layer, an outer conductive layer, an outer conductor and an outer insulation/jacket. At places where two cable parts have to be connected, these layers have to be re-built in the same way, by applying a cable joint or cable splice. At the terminating end of a cable, the layers have to be treated such that they can withstand the resulting electrical and environmental stresses. This is done by the mounting of a cable termination.
Apart from these two main types of cable accessories, there are several combinations and modifications, such as connectors and pluggable systems. Major resulting tasks include:
1. Electrical connection
2. Field grading
4. Withstanding weathering.
The first silicone cable accessories were developed in the late 1960s and appeared together with the first extruded XLPE cables. The focus by engineers at the time was on a design with field-grading and insulating parts in a pre-fabricated body that allowed easy assembly and avoiding mounting errors. The first parts of both, terminations and joints, were still rather massive since the electrical behavior of silicone was not yet fully understood. Still, test results and initial service experience (in comparison to the at the time state-of-the-art polyurethane and other solutions) were encouraging.
This idea of a pre-fabricated, silicone-elastomeric body remained and has since been expanded further. Today, having gained long-term service experience with the unique combination of properties of silicone elastomers, customers enjoy availability of a wide portfolio of silicone elastomer types. There are also auxiliary silicone materials for medium- and high-voltage cable accessories.
Attend the 2017 INMR WORLD CONGRESS in Barcelona-Sitges from November 5 to 8 to hear a paper by Jens Lambrecht that will review and present the most important aspects of this topic.