Space charge measurement under high hydrostatic pressure

Polyethylene is widely used as insulation in submarine DC cables due to its excellent dielectric property and mechanical performance. However, the problems caused by space charge have kept focusing much attention, which threaten the fatigue life of the insulators, and will further affect the insulation performance and service life of the DC cables. Considering the very harsh underwater environment, such as extreme pressure, it is of great significance to study the behavior of space charge under these conditions. In this paper, a dedicated setup comprising a Piezoelectric Induced Pressure Wave Propagation measurement system inclosed with the sample between two steel mold and subjected to high hydrostatic pressure has been developed, an acoustic pulse generator is specifically designed so that the system can be used reliably and stably to detect the space charge distribution in the dielectric materials. With this setup, linear low-density polyethylene (LLDPE) planar samples are subjected to a high hydrostatic pressure which is up to 100 MPa, and preliminary results are presented and discussed.