CYG PRS-7367 - CT Supervision Block

Protection Functions
218 PRS-7367
Ir
Id
Idl
Idh
k2
k1
o
Ir1 Ir2
Section1 Section2 Section3
NON
OPERATE
INST
OPERATE
DIFF
OPERATE
Default k2=1
Figure 3.46-5 Differential protection action characteristic curve (three sections)
87MP_DIF_EnableSET
SIG 87MP_Block
Ida>IdhANA
Idb>IdhANA
Idc>IdhANA
87MP_HS_StrA
SIG
87MP_HS_OpA
SIG
8ms
&
&
SIG Blk_OpHS
&
87MP_HS_BlkA
SIG
&
87MP_HS_StrB
SIG
87MP_HS_OpB
SIG
8ms
&
87MP_HS_BlkB
SIG
&
87MP_HS_StrC
SIG
87MP_HS_OpC
SIG
8ms
&
87MP_HS_BlkC
SIG
Figure 3.46-6 The Logic of Biased Low Stage differential protection
3.46.5 CT Supervision Block
CT disconnection judgment does not consider (1) simultaneous disconnection of three-phase
CT and simultaneous disconnection of phase and neutral sides CT; (2) The fault and CT
disconnection occur simultaneously.