Brushed DC motor is having lower efficiency and susceptibility of the communicator assembly to mechanical wear and consequent need for servicing. ECMA motors can directly replace the existing Brushed DC motors and fractional horsepower Induction motors of the Permanent split / capacitor-start, Shaded pole instruction, used In direct drive fans, HAVOC (Heating, Ventilating, and Alarm Controlling) systems and Refrigerators.
Many applications employ the use of an SCAR (silicon-controlled rectifier) speed controller on a single or 3-speed motors and this is not the most efficient technology, as they are fundamentally fixed-speed and also due to acoustical considerations, the fan motor is usually adjusted to operate at considerably less than full load (where SC motor efficiencies may be as high as 62 %) SC motor efficiency drops off dramatically when turned down, typically by at least Alfa. Installed SC motor efficiencies are therefore typically In the range of only 12-45%.
ECMA motors in contrast, maintain a high efficiency of 65-72% at all speeds. Unlike a brushed DC motor, the commutation of a ECMA or BLOC (Brushes DC Motor) motor is controlled electronically and to rotate the BLOC motor, the stator windings should be energize in a sequence. It is important to know the rotor position in order to understand which winding will be energize following the energize sequence. Rotor position may be sensed using Hall effect sensors embedded Into the stator. No f Hall effect sensors may vary based on the construction requirements.
Most of the BLOC motors have three Hall sensors embedded into the stator on the non-driving end of the motor, based on the hall sensors the controller will produce controlled signals to the motor. The controller can be used to controller the motor as well as to protect the motor during motor abnormal operation (Locked rotor, Loss of phase, No load and Over load condition). There are different types of ECMA motor constructions given In Flag. L and 3. Fig. L- Different ECMA Motor construction Fig. 2 – Induction Motor Fig. 3 – ECMA motor open view
Comparisons between ECMA and Brushed DC motor: Features Commutation ECMA motors Electronic commutation based on Hall position sensors. Less required due to absence of brushes Flat – Enables operation at all speeds with rated load. DC motors/lunation motor * Brushed commutation. Maintenance. Speed/Torque characteristics High – No voltage drop across brushes. High – Reduced size due to superior thermal Characteristics. Because ECMA has the windings on Stator, which is connected to the case, the heat dissipation is better. Periodic maintenance is required Moderately flat – At higher speeds, brush friction increases, thus reducing useful torque*.