"220V Cooling Fan" calculate thermal convection mode integrated power modules and an equivalent thermal radiator air. Depending on the air temperature of the substrate temperature, total power consumption and the total thermal resistance (contact surface of the substrate and heat sink thermal resistance and heat sink thermal resistance between the air) values. "220V Cooling Fan" heat sink to the thermal resistance between the air depends on the following factors: the material and geometry, air temperature, air density and air flow rate of the heat sink. The thermal resistance of the heat sink can also be determined by the relationship between the thermal resistance and the wind speed, the thermal resistance must be less than the calculated thermal resistance. If you meet the requirements of the thermal resistance can be obtained to meet the requirements of thermal resistance by changing "220V Cooling Fan" in the quantity and characteristics, or to reconsider the housing structure.