Protection Engineering Basics and Schemes Protection Engineering | Page 85

both main protection circuit Main-1 and Main-2 power
will be supplied from 125V dc supply, both supply is
equipped with MCBs. this shows that our protection
panel is DC powered so in case of grid AC supply failure
or fault in Grid the relays will remain effective.
in next drawing , we will review CT circuit
in this the CT is wired 1st in Test block , then from test
block it is wired to the relay , here you can CT is Star
connected , see contact 3S1 contact of R,Y and B phase
CTs are connect with each other to form Earth (return
path) .
pg. 85