Electrical resistivity-temperature characteristics enhancement of insulating cross-linked polyethylene composites by incorporating positive temperature coefficient particles with different Curie temperatures

Incorporating positive temperature coefficient (PTC) ceramic particles into polymers provides a prospective alternative solution for suppressing severe electric field distortions caused by negative temperature coefficient (NTC) of electrical resistivity within polymer insulation in high voltage direct current cable. The effect of the Curie temperature of PTC particles on the inhibition of the NTC effect of cross-linked polyethylene (XLPE) is investigated in this study. Positive temperature coefficient particles with varied Curie temperatures are surface-modified and melt blending with XLPE. The modified particles are dispersed on averagely in the matrix. The electrical resistivity, space charge behaviour, and direct current (DC) electrical breakdown strength of the samples are investigated at different temperatures, exploring the effect of the Curie temperature of PTC particles on suppressing the NTC effect of XLPE. It is demonstrated that the reduction in Curie temperature can further suppress the NTC effect of XLPE, enhance the DC strength at elevated temperatures, and inhibit the internal space charge accumulation. The reduction in the Curie temperatures means that the initiation of the PTC effect advances, exhibiting a higher potential barrier and inhibiting the NTC effect more effectively. This work may give a reference for improving the temperature stability of DC properties for XLPE cable insulation.