The Fundamental Characteristics of PPLP as Insulating Material for HTS DC Cable

Abstract

A high- superconducting (HTS) dc cable system consists of an HTS conductor, cooling system, insulating materials, and high-voltage insulation. The insulating materials and high-voltage insulation at cryogenic temperature can be developed for longer life, reliability, and compactness of HTS dc cables. Polypropylene laminated paper (PPLP) has been widely used as an insulating material for HTS ac cables. However, the dc dielectric characteristics of PPLP in liquid nitrogen have not been revealed satisfactorily until now. In order to develop the HTS dc cable, it is important to understand the fundamental characteristics of PPLP. In this paper, we research the fundamental characteristics of PPLP for HTS dc cables and the volume resistivity, space charge, and the dc breakdown characteristics of PPLP in LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The findings of our research were studied under dc and lightning impulse voltage and imply that the PPLP may be used as an insulating material for HTS dc cables.