Silicone grease(SG)is used for lubrication during cable accessory installation and can penetrate into the silicone rubber(SiR),leading to properties deterioration of the SiR.In this study,the effects of SG on the brea...Silicone grease(SG)is used for lubrication during cable accessory installation and can penetrate into the silicone rubber(SiR),leading to properties deterioration of the SiR.In this study,the effects of SG on the breakdown characteristics of the cross-linked poly-ethylene(XLPE)-SiR interface are investigated.First,the variation of the XLPE-SiR interface breakdown voltage with SG coating time is experimentally explored.The interface breakdown voltage significantly increases after SG is applied,remains stable for coating times of up to approximately 144 h and then rapidly decreases;the minimum interface breakdown voltage is lower than that without the SG coating.Next,the effects of SG on the chemical composition and surface topography of the SiR are examined by infrared spectroscopy and optical profilometry,respectively.The SG penetration does not change the functional groups of the SiR but significantly increases its surface roughness.Finally,the interface electric-field distribution after coating with SG is analysed by finite-element simulation,revealing that the residual SG at the interface distorts the interface electric field after a long coating time.The increase in the SiR surface roughness caused by SG diffusion and the interface electric-field distortion caused by the residual SG together lead to the decrease of the interface breakdown voltage.展开更多
This paper analyses the impact of square wave pulse voltage deadtime on the partial discharge(PD)and the lifetime of turn-to-turn insulation.A bipolar repetitive pulse voltage with a deadtime of 0–10μs is produced u...This paper analyses the impact of square wave pulse voltage deadtime on the partial discharge(PD)and the lifetime of turn-to-turn insulation.A bipolar repetitive pulse voltage with a deadtime of 0–10μs is produced using double half-bridge solid-state switches having push–pull technology controlled by a field-programmable gate array.The mechanism of the discharge process at rising and falling edges of the pulse voltage before and after deadtime is analysed in detail.The discharge amplitude and PD probability at the rising/falling edges of the voltage waveform increase as the deadtime increases from 0 to 10μs due to the remanent charges.The number of PD and their intensity is higher at the first rising/falling edges of pulse voltage as compared to the second rising/falling edges for all deadtimes 0–10μs.As the deadtime increases beyond 2μs,the number of PDs increases and concentrates at a specific phase angle of rising/falling edges.These localise discharges degrade the insulation material and reduce its lifetime.This study helps to identify the inverter-fed motor insulation faults due to deadtime.It can provide guidelines to motor insulation designers to determine the limit value of deadtime to compensate PD and ensure the safer operation of such motors.展开更多
基金Basic Applied Study of Sichuan Province,Grant/Award Number:2021YJ0538National Natural Science Foundation of China,Grant/Award Numbers:NSFC 51877142,NSFC 52107158。
文摘Silicone grease(SG)is used for lubrication during cable accessory installation and can penetrate into the silicone rubber(SiR),leading to properties deterioration of the SiR.In this study,the effects of SG on the breakdown characteristics of the cross-linked poly-ethylene(XLPE)-SiR interface are investigated.First,the variation of the XLPE-SiR interface breakdown voltage with SG coating time is experimentally explored.The interface breakdown voltage significantly increases after SG is applied,remains stable for coating times of up to approximately 144 h and then rapidly decreases;the minimum interface breakdown voltage is lower than that without the SG coating.Next,the effects of SG on the chemical composition and surface topography of the SiR are examined by infrared spectroscopy and optical profilometry,respectively.The SG penetration does not change the functional groups of the SiR but significantly increases its surface roughness.Finally,the interface electric-field distribution after coating with SG is analysed by finite-element simulation,revealing that the residual SG at the interface distorts the interface electric field after a long coating time.The increase in the SiR surface roughness caused by SG diffusion and the interface electric-field distortion caused by the residual SG together lead to the decrease of the interface breakdown voltage.
基金National Natural Science Foundation of China,Grant/Award Number:51977134。
文摘This paper analyses the impact of square wave pulse voltage deadtime on the partial discharge(PD)and the lifetime of turn-to-turn insulation.A bipolar repetitive pulse voltage with a deadtime of 0–10μs is produced using double half-bridge solid-state switches having push–pull technology controlled by a field-programmable gate array.The mechanism of the discharge process at rising and falling edges of the pulse voltage before and after deadtime is analysed in detail.The discharge amplitude and PD probability at the rising/falling edges of the voltage waveform increase as the deadtime increases from 0 to 10μs due to the remanent charges.The number of PD and their intensity is higher at the first rising/falling edges of pulse voltage as compared to the second rising/falling edges for all deadtimes 0–10μs.As the deadtime increases beyond 2μs,the number of PDs increases and concentrates at a specific phase angle of rising/falling edges.These localise discharges degrade the insulation material and reduce its lifetime.This study helps to identify the inverter-fed motor insulation faults due to deadtime.It can provide guidelines to motor insulation designers to determine the limit value of deadtime to compensate PD and ensure the safer operation of such motors.
