Abstract
In this paper, we propose a method on improving direct current (DC) dielectric performance by designing a polystyrene (PS) pinning crosslinked polyethylene (XLPE) for the application of insulation materials on high voltage direct current (HVDC) extruded cable. Electrical experimental results show that the addition of PS (1–5 phr, parts per hundreds of resin) can significantly reduce DC conductivity and increase DC breakdown strength of XLPE in the test temperature range of 30–90 °C. Microstructure investigation shows PS distributed as particles could participate in the formation of a crosslinking network with the help of a crosslinking agent, thus forming a polymer pinning structure at the interface between XLPE and PS. It is believed that such a special design strengthens the structure of XLPE, which leads to the improved DC dielectric performance at elevated temperatures. Our findings may contribute a new solution for developing HVDC cable insulation materials.
Highlights
Crosslinked polyethylene (XLPE) has been employed as the mainstream insulation material for high voltage direct current (HVDC) extruded cables owing to its excellent comprehensive performance and maturity in cable industry utilization
In nano-composites, polymers filled with appropriate nano-particles have been found to exhibit the superior properties of reduced DC conductivity and enhanced DC breakdown strength, originating from the suppression of space charges caused by nano-particle/polymer interfaces [8,9,10]
It should be noticed that the above-mentioned methods succeed in improving the DC performance of polyethylene, the cable insulation materials have always been subjected to stringent conditions with high electric fields at an elevated temperature, which largely changes DC dielectric properties and leads to a high degree of electric field distortion triggering
Summary
Crosslinked polyethylene (XLPE) has been employed as the mainstream insulation material for high voltage direct current (HVDC) extruded cables owing to its excellent comprehensive performance and maturity in cable industry utilization. For non-filled XLPE, unnecessary deterioration of direct current (DC) performance in high electric fields has been avoided through restricting the impurities caused by base materials and crosslinking reactions (e.g., employing purified LDPE and lowering the crosslinking degree) [5,6,7]. It should be noticed that the above-mentioned methods succeed in improving the DC performance of polyethylene, the cable insulation materials have always been subjected to stringent conditions with high electric fields at an elevated temperature, which largely changes DC dielectric properties and leads to a high degree of electric field distortion triggering
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