The 790-ECM Series Electronic Motor Speed Controller is designed to provide proportional speed control for energy efficient ECM (brushless dc) motors for variable air volume applications. Like the 791 and 792 controllers, the input is a DC voltage or current and the output is a PWM signal. The 792-ECM(VmA) Series is line voltage independent and requires only a 24 VAC power source. However the 790-ECM controller also allows an optional 266-PI Interface card that can drive the output signal until an external measured variable (temperature, flow, or pressure) is satisfied.

This controller also provides independent maximum and minimum speed limit adjustments. Also included is a separate continuous minimum speed or “drop out” function at minimum input signal.

Motor speed control is accomplished via a pulse width modulated signal from the 792-ECM which drives the ECM motor through it's dedicated control signal input.

This variable speed controller is used for adjustment of motor RPM. The controller is designed for air moving applications using squirrel cage or propeller type fans. As an example, to maintain a set flow of air through a duct, use the 203-5 Flow Transducer and the 266-PI Interface.

This control may be suitable for other, non air-moving, direct drive motor applications.