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Siemens Actuators SAS.., SAT.. for valves CE1P4041en
Building Technologies Functions and control 2015-05-19
4.2.5 Detection of valve seat
The actuators feature force-dependent valve seat detection. After calibration, the
exact valve stroke is filed in the actuator’s memory.
If no force is built up in the calculated end position (e.g. in the event of temperature
effects for instance), the actuator continues to operate at a reduced positioning
speed until the nominal positioning force is restored. This ensures that the valve
always fully closes.
After a power failure, valve seat identification is not active – the actuators without
fail safe function define their stroke position on power resoration to be at 50%.
From now on, the actuator follows the positioning signal.
When the valve plug reaches its seat for the first time, the actuator readjusts its
stroke model.
The supposed position is 50%, Y = 2 V, the actuator travels 30% of the stored
valve stroke in the direction of "Actuator’s stem retracted".
If the actuator reaches the seat within this 30% travel, it interprets the position as
"Valve fully closed" and shifts the position of the valve’s stroke accordingly without
changing the extent of travel.
From now on, the actuator follows the changed valve stroke position.
This means: New position 0%, Y = 2 V, actuator travels 20% of the stored valve
stroke in the direction "Actuator’s stem extended".
SAS..
Example
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