Nate Core Practice Test 2025 – Comprehensive Exam Prep

The actual operating RPM of a PSC (Permanent Split Capacitor) blower motor is significantly influenced by the external static pressure. In HVAC systems, the static pressure is the resistance encountered by the air being moved by the blower. When static pressure increases, it causes the blower motor to work harder to maintain airflow, which can lead to a reduction in the speed (or RPM) of the motor under certain conditions.

In a real-world application, as the external static pressure increases due to duct restrictions, bends, or filters, the motor may not be able to achieve its rated RPM. This relationship is crucial for maintaining system efficiency and performance, as the blower must adapt to the static conditions of the system it operates within.

Motor design, the size of the blower, and the type of capacitor used can influence performance, but the external static pressure is the primary factor that directly affects the operational RPM in practical scenarios.