I-75 Electric Actuator Interface Unit

For electric actuators operated by low current, low voltage rated programmable controllers and computers.

 
Always an innovator in electric actuator design and applica- tions, Worcester Controls has developed the 1-75 Interface Unit, a new circuit board that allows electric actuators to be operated by program- mable controllers or computers while protecting these control devices from destructive voltage and higher current from the actuators. 

Development of the 1-75 unit opens up new possibilities for operation of electric actuators by electronically oriented control products. This include throttling, on/off, stepping and sampling operations 
with complete safety of all control components. The low cost and reliability of programmable control coupled with the protection offered by the 1-75 makes electrically actuated process a reality. The 1-75 Interface Unit is optional equipment in the Worcester Controls Series 75 electric actuator and can be modified to fit within the protective housings of most electric actuators presently on the market. The unit will operate safely in the actuators' NEMA enclosures. Circuitry is solid state, reducing heat, saving energy, and providing long life and high reliability. 

Principle of Operation

When a reversible electric actuator utilizing a split phase capacitor motor is energized by a programmable controller or any other type of electronic controller or computer, due to limit switch action, auto-transformer effect of unused winding, and capacitor voltage, higher voltage is fed back to the unused output of the programmable controller. High voltage and in-rush current can damage controller output components. The 1-75 acts as a solid state relay between the two and protects the outputs from destructive feedback.

Controllers with outputs that have low current ratings cannot be connected to electric actuator motors that require a current greater than the controller rating. The 1-75 solves this problem by driving the electric actuator with a totally separate current which is actuated by the controller command. Since it only operates a control circuit, the current rating of the controller is not a matter of concern, and the controller can be connected directly to the 1-75 equipped actuator for operation.

 

© Pneumatic Control, Inc. 1999/2000