CYG PRS-7367 - Page 75

Protection Functions
PRS-7367 67
The operation of the breaker failure protection can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
3.7.2.1 Enable element
SIG
50BF_Enable
50BF_Ena
SET
SIG
Block
&
50BF_ReTr_Ena
SET
50BF_T1_Ena
SET
50BF_T2_Ena
SET
1
50BF_DeaZoneCtl
SET
3.7.2.2 Start element
50BF_ResetAct
FLG
&
1
SIG
50BF_ExtStr
FLG
50BF_ExtStr1
SET
Ia>50BF_Cur_StrANA
Ib>50BF_Cur_StrANA
Ic>50BF_Cur_StrANA
1
SIG CB_Close
SET
&
&
&
1
1
&
I0>50BF_ResCur_StrANA
FLG50BF_CBFState
50BF_Chk_Mod=1
50BF_Chk_Mod=3
&
SET
50BF_CurResEna
I2>50BF_NegCur_StrANA
&
SET
50BF_CurNegEna
SET
50BF_Chk_Mod=4
&
SET
50BF_Chk_Mod=2