High voltage performance of bulk, and amalgamated, PE insulation systems: Part I. Space charge characteristics

The introduction of cable joints and optical repeaters into submarine telecommunication cable inevitably results in amalgamation regions in the polyethylene insulation. These amalgamation regions are known to increase the probability of high voltage breakdown, when compared with the bulk material. This increased risk has been attributed to the accumulation of space charge in the amalgamation regions. Measurement of the space charge accumulation (using the pulsed electro-acoustic technique), and calculation of the resultant electric field distributions of both press moulded LDPE and injection moulded LDPE containing an amalgamation zone were conducted. The space charge dynamics are discussed, and the roles of interfacial stress and Schottky injection on the space charge accumulation are detailed.