Which of the following are unique characteristics of an ECM motor?

An ECM motor, or Electronically Commutated Motor, is distinct due to its ability to operate at variable speeds, which allows it to adapt to varying load conditions. This flexibility is critical in applications where efficiency and performance must be optimized based on demand. Additionally, ECM motors internally convert AC (alternating current) to DC (direct current), enabling them to utilize sophisticated control algorithms for improved efficiency and reduced energy consumption.

This combination of variable speed operation and internal AC to DC conversion makes ECM motors particularly advantageous in heating and cooling systems, as they can maintain desired temperatures more effectively while using less energy than traditional motors. This is why the statement regarding variable speed and internal conversion accurately represents the unique characteristics of an ECM motor.