Description Of System; General Description; Features - Burkert 8791 Manuel D'utilisation

5. descripTiOn Of sysTeM
5.1. general description
The positioner Type 8791 is a digital, electro-pneumatic position controller for pneumatically actuated propor-
tional valves. The device incorporates the main function groups
- Position measuring system
- Electro-pneumatic control system
- Microprocessor electronics
The position measuring system measures the current positions of the proportional valve.
The microprocessor electronics continuously compare the current position (actual value) with a set-point position
value specified via the standard signal input and supplies the result to the position controller.
If there is a control difference, the electro-pneumatic control system corrects the actual position accordingly.
5.1.1.

features

version
•
Positioner:
The position of the actuator is regulated according to the position set-point value. The position set-point value
is specified by an external standard signal or via field bus.
• position measuring systems
- internal high resolution conductive potentiometer or
- external non-contact, non-wearing position measuring system (remote).
• Microprocessor-controlled electronics
for signal processing, control and valve control.
control module
•
The unit is operated via 2 keys and 4 DIP switches.
3 LEDs indicate the status of the unit.
control system
•
The control system consists of 2 solenoid valves and 4 diaphragm reinforcers. In single-acting actuators the
working connection 2 must be sealed with a threaded plug.
feedback (optional)
•
The feedback is implemented either via 2 proximity switches or via an 4 – 20 mA output.
The operator can change the initiators or limit positions via control lugs.
pneumatic interfaces
•
Internal thread G1/4"
electrical interfaces
•
Circular plug-in connector or cable gland
communications interface
•
For configuration and parameterization
• housing
Plastic-coated aluminium housing with hinged cover and captive screws.
12
english
Type 8791

Description of System