First, according to the performance and environmental parameters "220V Cooling Fan" power devices work properly when calculating power device junction temperature is operating within safe junction temperature, the judge need to install a radiator, To install the heat sink to calculate the corresponding resistance, a primary radiator; recalculate "220V Cooling Fan" power junction temperature, the power to determine whether the device junction temperature within safe junction temperature range, in order to determine whether or not to meet the requirements of the selected radiator; for to meet the requirements of "220V Cooling Fan "radiator should be optimized according to actual engineering.