Investigation of charge trapping behavior of LDPE using de-trapping characteristics

Formation of space charge in polymeric insulation is a critical issue in the design of high voltage electric systems. Accumulation of space charge accelerates the material aging and may lead to premature breakdown of the insulation. Therefore, it becomes increasingly important to understand the charge injection, trapping and de-trapping processes in dielectric under application of high voltage. In this paper, the charge trapping and de-trapping behavior of low density polyethylene have been investigated. A new experimental set-up has been developed to obtain the de-trapping characteristics of a charged dielectric sample. From the obtained response, the trapping parameters i.e. trap depth, trapped charge etc is evaluated. It was observed, that the trapped charges in LDPE specimen is mainly concentrated to two trap levels, one shallow trap level (0.85 eV) and one deep trap level (1.01 eV).