Effects of degassing duration on crosslinking byproducts of HVDC cable insulation

With the rapid development of power engineering and electronic technology, high voltage direct current (HVDC) extruded cable with low loss, long lifespan, high reliability has become a rising concern, especially in China. Whereas HVDC cable holds insulation with greater thickness and longer distance than other cables, crosslinking condition of crosslinking polyethylene (XLPE) in cable extrusion and the variation of crosslinking byproducts including α-methyl styrene, acetophenone and cumyl alcohol, which have effects on the dielectric properties of cable insulation, are still in need of further research. The temperature and duration in factory degassing of HVDC cable have been handled in accordance to experience so far. In this paper, the effect of duration in factory degassing on crystallinity and crosslinking byproducts of HVDC cable insulation is studied. During the degassing, small grains are taken crystallization in outer insulation. No obvious change of crosslinking degree has taken place in HVDC cable after degassing treatment, as well as α-methyl styrene and cumyl alcohol content, while the relative content of acetophenone in crosslinking byproduct has varied significantly. And there is a variety of relative content of acetophenone in radial direction.