The surface trap parameter can significantly affect the development of surface flashover in vacuum,but the effective mode and mechanism are not very clear yet.The trap parameters of three polymeric materials were test...The surface trap parameter can significantly affect the development of surface flashover in vacuum,but the effective mode and mechanism are not very clear yet.The trap parameters of three polymeric materials were tested and calculated by means of isothermal surface potential decay.The flashover experiment was developed under different applied voltages.The results show a positive correlation between the withstand voltage and the deep trap,i.e.,the deeper trap energy level is,the higher flashover voltage is.The dynamics process of charge trapping and detrapping was analyzed based on the charge transport model in dielectrics with a single trap level and two discrete trap levels.The time of charge trapping was compared with that of the discharge development.The results show that the charge trapping time is longer than the flashover development time.The way to influence flashover for a trap is not to decrease the secondary electrons in single discharge development,but to change the electric field distribution on the dielectric surface by charge capture.展开更多
Operating conditions of film capacitors are complex,and the problem of film insulation failure caused by repetitively pulsed voltage is becoming ever serious.Degradation of the film under repetitively pulsed voltage c...Operating conditions of film capacitors are complex,and the problem of film insulation failure caused by repetitively pulsed voltage is becoming ever serious.Degradation of the film under repetitively pulsed voltage cannot be accurately evaluated by the average breakdown electric field.In this paper,the effects of pulsed electric field and pulse repetition frequency on the breakdown in biaxially oriented polypropylene(BOPP)films are investigated.Three phases of BOPP degradation are proposed based on the voltage amplitude,i.e.,maintenance(M),decline(D),and near-zero(N).Evolution of the BOPP film from degradation to breakdown at different frequencies is presented.Meanwhile,transition of discharge mode and elemental composition of the film are analyzed.Experimental results show continuous heat generation under repetitive microsecond pulses is the dominant factor for degradation of BOPP film.The number of applied pulses and the repetitive stressing time decrease exponentially with increase of frequency.This research can be contributed to the safe and reliable operation of capacitors.展开更多
基金supported by National Natural Science Foundation of China(Nos.51977202,U1830135,51807189)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.YJKYYQ20170004).
文摘The surface trap parameter can significantly affect the development of surface flashover in vacuum,but the effective mode and mechanism are not very clear yet.The trap parameters of three polymeric materials were tested and calculated by means of isothermal surface potential decay.The flashover experiment was developed under different applied voltages.The results show a positive correlation between the withstand voltage and the deep trap,i.e.,the deeper trap energy level is,the higher flashover voltage is.The dynamics process of charge trapping and detrapping was analyzed based on the charge transport model in dielectrics with a single trap level and two discrete trap levels.The time of charge trapping was compared with that of the discharge development.The results show that the charge trapping time is longer than the flashover development time.The way to influence flashover for a trap is not to decrease the secondary electrons in single discharge development,but to change the electric field distribution on the dielectric surface by charge capture.
基金supported in part by the National Natural Science Foundation of China-State Grid Joint Fund for Smart Grid under Grant U2166215.
文摘Operating conditions of film capacitors are complex,and the problem of film insulation failure caused by repetitively pulsed voltage is becoming ever serious.Degradation of the film under repetitively pulsed voltage cannot be accurately evaluated by the average breakdown electric field.In this paper,the effects of pulsed electric field and pulse repetition frequency on the breakdown in biaxially oriented polypropylene(BOPP)films are investigated.Three phases of BOPP degradation are proposed based on the voltage amplitude,i.e.,maintenance(M),decline(D),and near-zero(N).Evolution of the BOPP film from degradation to breakdown at different frequencies is presented.Meanwhile,transition of discharge mode and elemental composition of the film are analyzed.Experimental results show continuous heat generation under repetitive microsecond pulses is the dominant factor for degradation of BOPP film.The number of applied pulses and the repetitive stressing time decrease exponentially with increase of frequency.This research can be contributed to the safe and reliable operation of capacitors.
