Siemens SIPROTEC 7SJ62 Manual page 394

Mounting and Commissioning
3.1 Mounting and Connections
Figure 3-1
Trip Circuit Supervision for 7SJ62/64/
Please note that two binary inputs or one binary input and one bypass resistor R must be connected in series.
The pick-up threshold of the binary inputs must therefore stay substantially below half the rated control DC volt-
age.
If two binary inputs are used for the trip circuit supervision, these binary inputs must be volt-free i.o.w. not be
commoned with each other or with another binary input.
If one binary input is used, a bypass resistor R must be used (see following figure). The resistor R is inserted
into the circuit of the 52b circuit breaker auxiliary contact to facilitate the detection of a malfunction also when
the 52a circuit breaker auxiliary contact is open and the trip contact has dropped out. The value of this resistor
must be such that in the circuit breaker open condition (therefore 52a is open and 52b is closed), the circuit
breaker trip coil (52TC) is no longer energzied and binary input (BI1) is still energized if the command relay
contact is open.
Figure 3-2
394
Connection diagram (example) for setting group switching using binary inputs
Trip circuit supervision with one binary input
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008