Manual 37941A DTSC-200A - ATS Controller - Operation
© Woodward Page 23/37
Limit Switch Monitoring (Mechanical Failure, LM 21.11)
Functional Description
If the "Limit switch monitoring" function (parameter 3430, refer to the Configuration Manual 37940 for more in-
formation about the parameter) is enabled, it is always active, if no transfer command (C2, C1, C2O, C1O) is cur-
rently being issued by the ATS controller. The DTSC-200A evaluates the currently present and with use limit
switch open replies (parameter 3434) pre-selected replies from the ATS limit switch together with the currently
available source to determine which reply signals are currently expected to be able to supply the load.
The plausibility of the ATS limit switch replies will be monitored if a plausibility conflict (see Truth Tables on
page 24) is detected, After the ‘Limit switch failure delay time’ (parameter 3463) the ATS controller blocks all
further automatic transfers and displays the "Limit switch fail" message together with the actual and expected re-
plies. LM 21.11 ‘Mechanical Fail’ becomes true.
Figure 3-2: Limit switch monitoring - failure message
"Actual" indicates the reply messages, which are currently detected by the ATS limit switch.
"Expected" indicates the reply messages, which are expected to be detected by the ATS limit switch.
A continued automatic operation of the ATS controller is only possible after the "Actual" state matches the "Ex-
pected" state again. A "Reset" can be performed with the Return-button if this is the case. The button must be
pressed by the operator (or LogicsManager parameter 12891 „Reset limit switch failure“ must become TRUE) to
acknowledge the detection and the removal of the failure.
Signal and Command Abbreviations
• S1 Signal: breaker in source 1 position
• S2 Signal: breaker in source 2 position
• S1O Signal: breaker in source 1 OPEN position
• S2O Signal: breaker in source 2 OPEN position
• C1 Command: close to source 1
• C2 Command: close to source 2
• C1O Command: open from source 1
• C2O Command: open from source 2
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