Energy Saving Axial Fan And Centrifugal Fan Pwm Variable Speed Ec Motor 

Electronically Commutated (EC) motor is combines AC and DC voltages, bringing the best of both technologies. The principle is permanent-magnet brushless DC motor within the rotor, the stator is driven by electronic switches (which replace the Carbon brushes), controlled by a micro-controller.
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The EC external rotor motor is very compact because of its integrated bearing system which is particularly suited to meet the requirements of air moving solution. The integration of the motor inside the impeller results in extremely compact designs and high performance density. All rotating parts are directly finned to one component and dynamically balanced. This guaranteed low loads of the bearing systems. The high efficiency helps to keep the energy costs at a low level. Temperature rise is low since an EC motor generates approx only 1/3 of the heat loss known for conventional AC single and three-phase motors. This contributes to long motor life.  The electronics can be either integrated onto a PCB inside of the motor of can be separated unit.