Which type of blower motor is commonly used on air handling equipment with capacities of 4,000 cfm or greater?

A belt driven motor with three phases is commonly used on air handling equipment with capacities of 4,000 cfm or greater due to its ability to efficiently handle high airflow while providing the necessary power. This type of motor is particularly suited for larger systems because it allows for a greater range of control over speed and performance. The belt drive system also enables the motor to operate at a distance from the blower, facilitating design flexibility and ease of maintenance in larger installations.

Belt-driven motors can accommodate varying loads and can be easily adjusted for different airflow requirements by changing belts or pulley sizes. This capability is essential in larger air handling systems, where airflow demand can vary significantly. Additionally, three-phase motors are more efficient and produce more power than their single-phase counterparts, making them ideal for high-capacity applications.

In contrast, the other options may not provide the same level of efficiency, power, or adaptability needed for larger air handling systems. For example, direct drive single-phase motors and single-phase squirrel cage motors are typically used in smaller systems due to their limited capacity. Similarly, ECM (Electronically Commutated Motors) are often used for variable speed applications in smaller systems where energy efficiency is crucial but may not deliver the necessary power levels for larger capacities like