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of main observation and conclusion Paraffin, as an excellent phase change material (PCM), is limited by the leakage problem and low thermal conductivity. In this research, a novel paraffin/neopentyl glycol dimethacrylate/boron nitride (paraffin/NPGDMA/BN) composite PCM was successfully prepared via a physical mixing process. NPGDMA in paraffin/NPGDMA/BN composite PCM was cured by UV light under the action of photo initiator, which can improve the shape stability to avoid the leakage of paraffin in the process of phase change. By comparing the leakage rate, latent heat, and thermal conductivity, the optimal mass ratio of paraffin and NPGDMA was selected to be 7 : 3. It was showed that the presence of 5 wt% BN led to increasing in thermal conductivity by up to 59%. The microstructure of the composite PCMs was characterized by SEM, FTIR, and XRD. The composite PCMs can be processed into a variety of shapes by using molds. The paraffin/NPGDMA/BN composite PCM exhibited a significantly improved shape stability and large phase change enthalpy of 123.0 J/g. The leakage rate of paraffin/NPGDMA/BN was much improved after being soaked with petroleum ether.

In this paper, the causes of partial discharge in GIS and the existing detection methods are described, and signal processing and pattern recognition method of insulation defect in UHF detection method are introduced emphatically.