CYG PRS-7367 - Non-directional earth-fault protection 51 G

Protection Functions
48 PRS-7367
No.
Name
Values(Range)
Unit
Step
Default
Description
20
67Pi_PTS_Blk
0-1
-
1
0
The Stage i Protection PTS Alm
Block enable/disable:
0: Open 67Pi VCE and Dir
function, the Protection become
51Pi.
1: Block 67Pi, then the 51PVTi
should be enabled
3.4 Non-directional earth-fault protection 51G
3.4.1 51G Overview
This relay provides four stages of non-directional earth-fault overcurrent protections with
independent definite time and inverse definite minimum time characteristics. Each stage can have
been abled or disabled independently by the corresponding logic setting respectively.
When this relay is used in small resistance grounding system, the grounding zero sequence
current during earth fault is larger and can be used for tripping directly. All stages are equipped for
the zero sequence overcurrent protection. In this case, the zero sequence current for tripping can
be calculated or directly derived from a zero sequence current transformer.
3.4.1.1 Function Block
The function block of the protection is as below.
I3P
OCTG_51G
Blk
Blk _Str
Blk _Op
Str
Op
Ena _Mult
Figure 3.4-1 Function block
3.4.1.2 Signals
Table 3.4-1 Input Signals
Signal
Description
I3P
The current magnitude in all the three phases
Blk
This signal blocks all the binary output signals of the function
Blk _Str
This signal blocks all the start outputs of the function
Blk _Op
This signal blocks all the trip signals of the function.