4.2.2 Directional ground-fault protection 67/51N, 67/50N
4.2.2.1 Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Directional ground-fault protection, low
stage
DEFLPDEF I0> -> 67/51N
Directional ground-fault protection, high
stage
DEFHPDEF I0>> -> 67/50N
4.2.2.2 Function block
TRIP
PICKUP
BLOCK
67/51N
I
2
U
2
IG
VG
RCA_CTL
ENA_MULT
TRIP
PICKUP
BLOCK
67/50N
I
2
U
2
IG
VG
RCA_CTL
ENA_MULT
GUID-7CA3F40E-E448-4D5D-8D1C-59F2D1DDF29C V1 EN
Figure 150: Function block
4.2.2.3 Functionality
The directional ground-fault function 67/51N, 67/50N is used as directional ground-fault
protection for feeders.
The function picks up and trips when the operating quantity (current) and polarizing
quantity (voltage) exceed the set limits and the angle between them is inside the set
operating sector. The trip time characteristic for low stage (DEFLPDEF) and high stage
(DEFHPDEF) can be selected to be either definite time (DT) or inverse definite minimum
time (IDMT).
In the DT mode, the function trips after a predefined trip time and resets when the fault
current disappears. The IDMT mode provides current-dependent timer characteristics.
The function contains a blocking functionality. It is possible to block function outputs,
timers or the function itself, if desired.
4.2.2.4 Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are “Enable” and “Disable”.
Section 4 1MAC059074-MB A
Protection functions
326 615 series ANSI
Technical Manual
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