42 / 60
Siemens
Actuators SAS.., SAT.. for valves
CE1P4041en
Smart Infrastructure
Functions
and control
2019-04-09
4.4
Technical and mechanical design
4.4.1
Transmission of power
Incoming positioning signals are translated to positioning commands for the motor.
A gear train transmits the motor’s positioning steps to the output stage. Here, the
translation from rotary to stroke movement takes place. Attached to the gear train
are the electrical and mechanical accessory items and the manual adjuster. With
the stroke actuators with fail safe function, the gear train also accommodates the
return spring.
4.4.2
Kopplung
SAS.., SAT..
Antriebsstössel und Ventilstössel stossen
aufeinander. Sie sind nicht fix miteinander
verbunden.
4.4.3
Fail safe function
The fail safe function works mechanically with a return spring and ensures the
protection of the plant. It guarantees the safe operation in uncontrolled operating
states.
In the event of a power failure, the actuator will return to its 0 % stroke position with
the help of the return spring, closing the valve. The Y positioning signal is not
valued.
Fail safe
function
Actuator
Valve
Spring return
time
At positioning
time
Active
Actuator’s stem
retracts
Spring in valve
closes
Valve closes
<8 s
1)
<14 s
1)
<28 s
1)
15 s
30 s
120 s
1)
Spring return time increased slightly at low temperatures
Function principle