Burkert Type 8693 - Manual (Page 15)

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Description of system,
5.1. models of the positioner
The positioner is available in 2 versions:
type 8692 - positioner with positioning control
The position of the actuator (stroke) is regulated according to the position set-point value. The position set-point
value is specified by an external uniform signal (or via field bus).
type 8693 - positioner with process control
The positioner is linked to a control circuit. The position set-point value of the valve is calculated from the process
set-point value and the actual process value via the control parameters (PID controller). The process set-point value
can be set by an external signal.
Pneumatically actuated piston actuators and rotary actuators can be used as a actuator. Both single-acting and
double-acting actuators are offered in combination with the positioner.
For single-acting actuators, only one chamber is aerated and deaerated during actuation. The generated pressure
works against a spring. The piston moves until there is an equilibrium of forces between compressive force and
spring force.
For double-acting actuators the chambers on both sides of the piston are pressurised. In this case, one chamber is
aerated when the other one is deaerated and vice versa. In this design, no spring is installed in the actuator.
english
Type 8692, 8693