ABB RELION SMU615 Technical Manual page 136

Supervision functions
Figure 87: Operating principle of the trip-circuit supervision with an external
resistor. The TCSSCBR blocking switch is not required since the external resistor
is used.
If TCS is required only in a closed position, the external shunt resistance can be
omitted. When the circuit breaker is in the open position, TCS sees the situation as a
faulty circuit. One way to avoid TCS operation in this situation would be to block the
supervision function whenever the circuit breaker is open.
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1MRS758407 C
SMU615
Technical Manual