Influence of Field Strength and Temperature on the Space Charge Distribution in Epoxy under DC Stress

The relevant physical mechanisms influencing the space charge accumulation in solid insulating materials for gas insulated systems are studied. Space charge measurements according to the pulsed electroacoustic method (PEA) in epoxy samples are performed under DC stress. The influence of temperature and field strength on the space charge distribution is clarified. The accumulation of homo charges is observed, even at short stress durations. It is explained by the injection of charge carriers from the electrodes into the material. At longer stress durations hetero charges accumulate close to both electrodes. The accumulated charge in the material increases with applied field strength. Higher temperatures accelerate the accumulation of homo and hetero charges.