This paper introduced an improvement scheme for the pneumatic circuit of the LW15-252 circuit breaker.By analyzing the composition and running principle of the apneumatic circuit

we investigated the basic structures and action principles of the inlet solenoid valve and moisture separator

redesigned the piston of the valve and the filter element of the moisture separator to preven the piston from break and the moisture separator from corrosion.Thus

the frequent failures of the pneumatic circuit disappeared

and the level of stable operation of the LW15-252 circuit breaker was greatly improved.In addition

this study has broken the monopolization of the foreign technology in China

and provides a good reference for updating the similar breakers with pneumatic mechanism.