Flowserve MX Electronic Actuator SIL Safety IOM - Manual (Page 21)

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Limitorque MX Electronic Actuator FCD LMENIM2350-01 – 9/13
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7.3.8 Actions Upon Successful Completion of the PST Stroke
• PST status shall be set to Passed.
• LCD indicates “STATUS OK.”
• Any status relay that is configured as PST Completed Successfully shall assume its configured state.
• Actuator resumes normal operation.
7.3.9 PST Timer
PST timer shall be calculated based on the operating stroke time and implemented as part of PST algorithm.
7.3.10 PST Timer Start
Maximum time limiting timer shall be triggered upon start of the forward and reverse directions of the PST. If the PST
timer times out before actuator reaches the desired position, then PST status shall be set to “Failed.”
7.3.11 PST Failure Events and Actions
PST status shall be set as failed if any one or more of the following happens when actuator is performing PST.
• Event: Actuator fails to reach target position before PST timer expires.
• Actions:
a. PST status shall be set to PST failed to reach target position in allotted time.
b. LCD indicates “STATUS OK” if no other fault is detected.
c. Any status relay that is configured as PST failed to reach target position in allotted time shall assume its
configured state.
• Event: Actuator fails to return to start position before PST timer expires.
• Actions:
a. PST status shall be set to PST failed to return to starting position in allotted time.
b. LCD indicates “STATUS OK” if no other fault is detected.
c. Any status relay that is configured as PST failed to return to starting position in allotted time shall assume its
configured state.
• Event: One or more system faults, valve jam, over temperature, over torque, etc.
• Actions:
a. Actuator stops motion.
b. LCD reports fault.
c. Monitor relay de-energizes.
d. PST status indicators set to either PST failed to reach target position in allotted time or PST failed to return to
starting position in allotted time as appropriate.