Electrical properties of solid insulators as a function of temperature and pressure

A high pressure (1500 bar) experimental device working in the -50C to 150C temperature range was built in order to measure the low and high frequency dielectric loss coefficient of insulating materials which are currently used in underwater telephone cables. Results related to polyethylene losses in the 0,1 to 15 MHz range show that these losses increase with pressure and frequency at a given temperature, while the permittivity diminishes at higher pressures. The experimental values present a rather large dispersion in spite of several corrections that were being considered.