9
Actuators with electronic control unit MWG including limit switches:
In this version, safe signaling can exclusively be ensured via limit switches. However, this
signal is not part of the certification by TÜV Nord. Please refer to the specific safety manual
for details regarding this signal.
For “SIL seating” = “no seating” (without end position protection), we recommend:
• To prevent valve damage during safety operation, we recommend, depending on the
stiffness, sizing the valve to 3 – 5 times the maximum actuator torque.
• To avoid thermal damage due to excessive currents, we recommend monitoring
(assessing) the motor protection.
For “SIL seating” = “Forced limit seating in end position”, the seating is performed via limit
switches in the end position. Since, each switch has a hysteresis, the actuator leaves the end
position prior to limit switch release. Consequently, there is a marginal range of actuator
positions to the safety position, for which the limit switch is still operated when leaving the
safety position, while the Safe ESD function is NOT available. In this case, safety function
triggering leads to actuator standstill. If the range in question is approached from the opposite
direction, this limitation does not apply. In general this range is relatively small. However, for
unfavorable configurations (low number of turns per stroke), this range can amount to more
than 10 % of the total stroke.
Should within the framework of unfavorable conditions the effect described above represent
an unacceptable limitation for the safety function, we recommend applying the configuration
“Forced torque seating in end position” or “no seating” for safety operation.
The plant operator is responsible for power supply.
3.2 Configuration (setting)/version
Configuration (setting) of safety-related functions is defined in the factory during actuator
controls assembly and validated during final inspection. Subsequent modification of the
configuration by the plant operator is not permissible.
General functions are set as described in the Operation instructions or the Manual (Operation
and setting) 3.XX EPAC actuator.
Configuration of safety-related functions is listed in the order-related technical data sheet.
Configuration options for safety function
Table 3:
When configuring a Safe ESD function and a Safe STOP function, the Safe ESD function is
always prioritized compared to the Safe STOP function when requested simultaneously.
Configuration options for safety function
Configuration
SIL function
Safe STOP in direction CLOSE and direction OPEN
Safe ESD CLOSE/CLOSE + Safe STOP
CLOSE/OPEN
Safe CLOSING and Safe STOP in direction CLOSE and direc-
tion OPEN
Safe ESD OPEN/OPEN + Safe STOP
CLOSE/OPEN
Safe OPENING and Safe STOP in direction CLOSE and direc-
tion OPEN
Multi-turn actuators
SA series with Control 3.XX /NI/SIL
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