Motorized Intake Damper; Permanent Split Capacitor (Psc) Motor Speed Control; Evo™/Ecm-Vcu - CaptiveAire D76 Installation, Operation And Maintenance Manual

Permanent Split Capacitor (PSC) Motor Speed Control

Some single-phase direct-drive fans contain speed controls that
regulate the amount of voltage going to the motor. Specific PSC
motors must be used in conjunction with speed controls. The
speed control has a knob (Figure 7) with an off position along
with high to low range. At high speed, the speed control allows
all of the line voltage to pass directly to the motor.
A minimum speed adjustment is provided to allow independent
control of the minimum speed setting. Minimum speed
adjustment ensures the motor runs with sufficient torque to
prevent stalling. To adjust this:
1. Motor must be in actual operating conditions to achieve proper speed adjustment. Motor will not slow
down unless proper load is applied.
2. Turn main control knob to lowest speed position.
3. Locate and adjust minimum speed setting. This can be found under the speed control faceplate. Use a
small screwdriver to adjust. Rotate clockwise to decrease minimum speed; counter-clockwise to
increase minimum speed.
4. Motor will now operate from this preset minimum speed to full speed.
The lowest minimum voltage that may be applied to these motors is 65V AC. Running lower
voltages to the motor can cause premature failure and overheating problems.
Figure 7 - PSC Motor Speed Control
13
Vari-Speed
OFF
SOLID STATE SPEED CONTROL