Fan motors have two basic types: PSC and EC. PSC motors are simpler to build and less energy efficient than EC motors. They also exhibit the same trade-offs as shaded pole motors. EC motors are the most energy efficient of the two types.
EC fan motors may have a variety of features, which are not industry-standard. These features include locked rotor protection, signal-level output, and sensor-based control. Locked rotor protection is a safety feature that indicates that the fan motor is protected from physical interference and bearing failure. The function of this feature may differ from a lockable rotor sensor, so it's important to check the specification carefully.
The technical data of an axial fan motor is typically presented as a table and a Q/h curve. The axis pitch (the angle at which the blades rotate) determines how much air is moved. The air flow is measured in cubic feet per minute. The number and material of blades, motor size, and pitch can influence air movement. Higher blade pitches compensate for lower motor size. Blades should also be sealed against moisture. Some manufacturers offer special coatings on the blades for improved resistance to water.
Electric power is another important characteristic of fan motors. Electric power is easier to measure than air flow. The efficiency of an air-conditioning unit depends on the fan's airflow. In case of low airflow, the unit cannot work properly and the motor may damage its components. Therefore, it's important to check the fan's speed to avoid any unexpected situations.