"220V Cooling Fan" blade balance between the performance of the entire DC fan, DC fan blade balance than being commonly used dynamic balance, it is the principle of adjustable vanes for DC fans and single-stage variable pitch type "220V Cooling Fan", because only one level of the impeller, mass imbalance caused due to wear it all focused on the impeller, the balancing process is a single plane balancing process, namely static equilibrium process. If it is determined the vibration caused by mass imbalance, so long as the measurement point of the horizontal or vertical direction in the vicinity of the bearing housing shell vibration, use of influence coefficient method, increase in the impeller, will be able to "220V Cooling Fan" to reduce vibration within the desired range.