Protection Engineering Basics and Schemes Protection Engineering | Page 82

we now moving forward , now we have DC logic Drawing
, remember we always kept DC in back up in any
substation , and also run our most controlling and
protection equipment via DC so when in case of power
failure we can get stored DC supply for protection and
control panel.
here you can see the SEL 487V relays is supplied from DC
supply 1 , BCPU, trip coil 1 via tripping relay 94 ,BCPU via
tripping relay 94,HMI /SAS signaling via tripping relay 94
pg. 82