The Self cleaning filter can use filter strainer to stop the water impurities directly, remove solids and particles in the water ,low turbidity, impurity water quality, so that the dirts algae corrosion will be less , And Water protection system and other higher precision filters equipments will be protected. Water enter into the filters from the inlet, as the design of PLC PAC, system can identification automatically for the degree of impurities , and give signal to blow-down valve to realize auto-discharge .