ABB RED615 Technical Manual page 580

Section 6
Supervision functions
574
Trip circuit supervision and other trip contacts
It is typical that the trip circuit contains more than one trip contact in parallel, for
example in transformer feeders where the trip of a Buchholz relay is connected in
parallel with the feeder terminal and other relays involved. The supervising current
cannot detect if one or all the other contacts connected in parallel are not connected
properly.
A070968 V3 EN
Figure 307: Constant test current flow in parallel trip contacts and trip circuit
supervision
In case of parallel trip contacts, the recommended way to do the wiring is that the
TCS test current flows through all wires and joints.
TCS
1YHT530004D05 D
615 series
Technical Manual