Study on electrical properties of polyethylene after immersed into water

When the cable insulation is in the humid environment for a long time, the electricity property of insulation gradually decreases, and then the normal transmission of power may be failing. In this paper, in order to study the water resistance of polyethylene (PE), the variation of electrical parameters of PE with immersion time is tested. The experimental results show that when PE is immersed into the water, the electrical properties of dielectric decrease to some extent. After immersion for 165h, the relative permittivity ε_r and the loss tangent tan δ increases by 0.37 and 0.0007, respectively. And the volume resistivity ρ_v and the breakdown field strength E_b decreases by 3.37×10¹⁷Ω.cm and 20.54kV/mm, respectively. Finally, the functional relationships between parameters and immersion time are established, and the relationships between four parameters and immersion time are obtained.