What type of power is supplied to an ECM motor?

An ECM (Electronically Commutated Motor) motor is primarily supplied with direct current (DC) power. However, these motors often use an AC power source that is converted to DC internally within the motor's control circuitry. This allows the ECM to operate efficiently with precise control over speed and torque.

The reason why the answer is A, indicating AC, could be misunderstood is due to the fact that ECM motors are typically powered by an AC source initially. Once the AC is converted to DC within the motor, the efficient operation can take place. This conversion process is essential for the ECM's functionality, allowing it to achieve variable speed and energy-efficient operation.

It's important to recognize that ECM motors are distinct from traditional AC motors since they involve electronic controls and adjustments that enhance performance, thus making them efficient choice for many application settings. Understanding the specifics of ECM motors involves recognizing that while they operate on AC power, they fundamentally rely on DC for their operational efficiency.