The 770-PSC Control offers a way to add existing single phase PSC or shaded pole motor fans to a building automation system. The 770-PSC control measures the motor's RPM, using an easy to attach sensor, and can adjust the motor's speed to match a chosen set point. The control can be operated locally using the 32 character LCD display and pushbuttons, or it can be operated over a Modbus RTU connection.

There are two modes of motor speed control available. In manual mode (open loop), the control provides a fixed power level to the motor indicated by a Speed Index ranging from 0 to 100%. The actual motor rpm will vary with changes in loading. In automatic mode (closed loop), the control uses a PI feedback algorithm to drive the sensed motor rpm to match an rpm set point (300 rpm minimum).

The 770-PSC is normally used to set and maintain the speed of PSC or shaded-pole motors between a selectable minimum speed and full speed. It uses a triac for power line switching to reduce motor speed. An external transformer (24 VAC) must be supplied to power the control.

The motor used with the 770-PSC Control must accept a phase proportioning input and be able to operate at minimum rpm for extended periods of time without overheating.