Forced Control Z; Communicating Actuators Modbus Rtu; Detection Of Valve Seat - Siemens Acvatix SAS Series Basic Documentation

SAS..
Example
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4.2.7

Forced control Z

Forced control uses the following operating modes:
No function
Equal-percentage or
linear characteristic
Contact "Z" not
connected,
valve follows
positioning signal "Y"
4.3

Communicating actuators Modbus RTU

4.3.1

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 upon return of power at 50%. And sets
its internal setpoint in register 1 to 0%. The actuator closes at this setting. There is
a short-term deviation between the setpoint and the internal stroke position that
results in an error message in register 769 "Mechanical error, device blocked". The
error message disappears after just a few seconds.
When the valve plug reaches its seat for the first time, the actuator readjusts its
stroke mode.
Setpoint prior to power outage 35%, no manual adjustment during the power
outage. Internal stroke position value after return of power 50%. Internal setpoint
after return of power 0%. There is an error message for a brief time prior to the
actuator moving since the setpoint of 0% is not equal to the position feedback of
Actuators SAS.., SAT.. for valves
Functions and control
Z mode
Fully open
Contact "Z" is Contact "Z" is
connected directly to connected directly to
"G",
positiong signal "Y" positiong signal "Y" has
has no impact
Overriding
Fully closed positioning signal "Y"
by 0...1000 Ω
Equal-percentage or
linear characteristic
Contact "Z" is
connected to "M" via
resistor "R",
starting point at 50 Ω,
"G0",
end point at 900 Ω,
no impact positioning signal "Y"
has no impact
CE1P4041en
2019-04-09