8
DescriptionofSystem
6
DESCRIPTION OF SYSTEM
6.1
General description
The positioner Type EP 501 / process controller Type EP 501 C
is a digital, electro-pneumatic position controller for pneumatically
actuated proportional valves. The device incorporates the main
function groups
- Position sensor
- Microprocessor electronics
- Electro-pneumatic control system
The position sensor 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 positioner/process controller.
If there is a control difference, the electro-pneumatic control system
corrects the actual position accordingly.
The device is operated with a 128 x 64 dot matrix graphics display
and a keypad with 4 keys.
6.2
Designs
6.2.1 Type EP 501, 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).
6.2.2 Type EP 501 C, process controller
Type EP 501 C also features a PID controller which, apart from actual
position control, can also be used to implement process control (e.g.
level, pressure, flow rate, temperature) in the sense of a cascade control.
The process controller 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.
6.2.3 Type EP 501 L remote operation with external
position sensor
In case of this model, type EP 501 C has no internal position
sensor in the form of a rotary position sensor, but is connected to
an external 4–20 mA remote sensor. As this is connected via the
analog interface, type EP 501 L can be operated as a positioner
(position controller) only.
english
Type EP 501
Summary of Contents for EP 501
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