At present

circuit breakers used in the ultra-high voltage field at home and abroad are mostly puffer circuit breakers or double-break self-blasting circuit breakers.The research on single-break self-blasting arc chamber is still blank in this field.Based on the theory of magneto-hydrodynamics

a two-dimensional dynamic arc mathematical model considering nozzle ablation is established in this paper to complete the simulation during arcing process of the high voltage SF

6

self-blasting circuit breaker und

er different interrupting conditions（effective short-circuit current is 63 kA and 40 kA

the arcing time is 12 ms、16.3 ms、20.8 ms respectively）.The results show that the maximum temperature of the 63 kA arc at the current peak is 28 900 K under 12 ms arcing condition

which is about 2 000 K higher than the condition of 40 kA.During the entire interrupting process

the highest pressure in expansion chamber can reach up to 3.78 MPa at 63 kA and 2.77 MPa at 40 kA.The difference in acting time of the check valve is tiny under different short-circuit current;corresponding to the three arcing time above;the acting sequence of the check valve is 16.3 ms

12 ms and 20.8 ms and the time lag is 0.1 ms in turn.At 40 kA

12 ms

the nozzle ablation quality is 6.34 g;while at 63 kA

corresponding to the above three arcing times

the ablation quality is 11.25 g

15.65 g and 19.44 g respectively.