Current to Position Converters for Electric Actuators
The Series 658 is a current to position converter which is typically located electrically between a primary controller and an electric actuator. Model 658A is designed for mounting directly to the side of the actuator; model 658B is designed with a mounting flange for securing it to any flat surface. The electric actuator’s position is proportional to the input current from the primary controller. A built-in potentiometer in the electric actuator, with wiper arm driven by the output shaft, provides a feedback signal to the Series 658 to produce the proportional action. A change in current from the source drives the electric actuator in a direction to restore balance and return the process to the setpoint. The signal input ordered is factory set, but is adjustable in the field to accept spans such as 4 to 20, 2 to 12, 7 to 12, 4 to 12, and 12 to 20mA. The Series 658 has a standard input impedance of 250 Ω for current output primary controllers. A special option (65 or 66 in the model number) is available on Model 658A that provides an extra input lead (white) for activation of the purge option used on a burner control. A dry contact closure between the purge input and the input+ (red) wires will drive the actuator full open to provide 100% flow for air purge of a gas burner. Converters with special “option 65” are wired for mounting on the left side of the actuator; converters with “option 66” are wired for the right side of the actuator.