Burkert 20010867, Руководство по эксплуатации, Страница: 11 / 42

11
Product description
Type 3281
- When the voltage is applied again, the control electronics automatically detect the current position.
• Reduction of energy consumption.
- The stepper motor is only supplied with energy when it opens or closes the valve further. Owing to the
internal holding torque, the stepper motor only moves when it is controlled. In the remaining time, only the
control electronics need a basic voltage supply in order to adjust or move the stepper motor and thus the
motor valve in the event of a change in the signal input.
5.3 Variants
Type Seat diameter Variants Options
3281 4, 6, 8, 10 with integrated positioner analogue
digital (fieldbus)
with integrated process
controller
analogue
digital (fieldbus)
Table 1: Variants
The variants with integrated positioner or process controller are available in 2 options:
• Analogue: Set-point values are transmitted analogue via the standard signals,
• Digital: Set-point values are transmitted digitally via CANopen/büS.
The variants can be recognized by the plug configuration or on the Type label: C stands for positioner
and D for process controller.
Both variants have special functions that can be set using the Bürkert Communicator.
5.3.1 Positioner
The positioner converts a set-point position into a valve position. The position of the actuator is regulated
according to the set-point position. The position sensor records the current position (POS) of the electro-
motive valve. This actual position is compared by the positioner with the set-point value (CMD) specified as
the standard signal. If there is a control difference (Xd1), a motor control signal is given to the actuator as the
actuating variable. Z1 is a disturbance.
Positioner
Position control loop
CMD CTRL POS
Z1
POS
Valve opening
+
Xd1
-
Position sensor
Continuous valve Electromotive
actuator
Set-point
position
Fig. 2: Signal Flow Plan Positioner
The two end positions of the valve are signaled by status LEDs. The actual position recorded by the position
sensor is output via the M12 circular plug-in connector. It is possible to communicate with the device digitally
via CANopen or büS.
english