For studying the corona pulse characteristics in SF

6

u nder DC voltages and exploring the effect of different polarity on the pulse stage development

the corona discharge experiment of SF

6

is performed by setting up a needle-to-plane model corona pulse platform. The typical corona pulse waveform in SF

6

at room temperature and atmospheric pressure is analyzed. The variation of pulse characteristic parameters under positive and negative polarities is compared. At the same time

the variation process of corona

pulse stage in SF

6

under different gap spacing is studied

and the pulse stage development at pressure of 0.3 MPa is verified. The experimental results show that the pulse characteristic parameters of SF

6

are basically identical under positive and negative polarities. The rise time

fall time

and pulse duration are in the range of 3～4 ns

13～15 ns

and 20～25 ns

respectively. The corona pulse stage of positive polarity is mainly divided into such three main stages as initial-pulse stage

streamer-pulse stage and brush-pulse stage. While

the corona pulse stage of the negative polarity is divided into such three other main stages as streamerpulse increasing stage

streamer-pulse decreasing stage and brush-pulse stage. With the increase of gap spacing

the current range of corona pulse stage increases

and the current ranges of brush-pulse stage in positive polarity and the streamer-pulse decreasing stage in negative polarity increase significantly.