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10.3.1 Detecting erroneous operation
(i) Operation logics
The TCS has six sets of monitoring logic (TCS1 to TCS6), as shown in Figure 10.3-1. For
example, the TCS1 logic issues a signal “TC1_Fail” when the following conditions are
determined in the TCS1 logic:
➢ Both signals at PLC connection points “TC1_FAIL_SIGNAL1” and “TC1_FAIL_SIGNAL2”
being absent for more than 0.4 sec.
➢ Either On or OPT-On† being set for scheme switch [TCS1-EN].
TCS2 scheme logic (same as TCS1 scheme logic)
TCS3 scheme logic (same as TCS1 scheme logic)
TCS4 scheme logic (same as TCS1 scheme logic)
TCS5 scheme logic (same as TCS1 scheme logic)
TCS6 scheme logic (same as TCS1 scheme logic)
Figure 10.3-1 Six sets of TCS scheme logic
†Note: If the user wishes to add a user-programmed condition for the TCS1 decision, set
OPT-On and connect the user-programmed signal at PLC connection point
“TC1_FAIL_COND”. The TCS1 monitor will then only be available when a user-
programmed signal is present at PLC connection point “TC1_FAIL_COND”.
(ii) Applications
Example1
Figure 10.3-2 provides an application example of the TCS function. Two binary-input signals
are assigned to PLC connection points “TC1_FAIL_SIGNAL1” and “TC1_FAIL_SIGNAL2”.
When the trip circuit is healthy, a small current will flow in the BI circuits, the CB auxiliary
contacts, and the trip coil. This small current can be observed to flow in both the CB-open
condition and the CB-closed condition. If the small current supplied to the trip circuit is lost,
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