5.9
Directional sensitive EF protection for grounded
system 67N (DIREFGND)
5.9.1
Mode of operation
GUID-2BFEE0BB-FBF7-404A-BA3F-A7CF1102EDE6 v1
High-resistance ground faults, which cannot be detected by the distance protection, can still
cause appreciable problems in spite of the relatively low fault currents involved.
The sensitive ground fault protection function has been included to complement the main line
protection function and cover the low ground fault current range. The protection processes
the zero-sequence components 3I
0
and 3U
0
.
5.9.2
Features
GUID-3D33BB3F-7C82-41CB-B322-7778B31D585C v1
•
Insensitive to DC component
•
Insensitive to harmonics
•
Directional measurement of zero-sequence components (derived either internally or
externally)
•
Current pick-up enabling level
•
Reference voltage enabling level
•
Adjustable characteristic angle
•
Permissive and blocking transfer tripping schemes
•
Echo logic for weak infeed and open circuit-breaker
•
Transient blocking logic for reversal of energy direction
5.9.3
Inputs and outputs
5.9.3.1
CT/VT inputs
GUID-CB029954-E781-47DD-ACCC-5BF0449C0C69 v1
•
Voltage
•
Current
5.9.3.2
Binary inputs
GUID-FCC3913A-72BB-43CD-B109-AD984CC4475A v1
•
External blocking
•
Receive
•
CB closed
•
VT supervision
•
Starting and tripping by the distance function
5.9.3.3
Binary outputs
GUID-BF84DA2A-D873-4040-A306-DC404723E033 v1
•
Pick-up
•
Trip
•
Fault forwards
•
Fault backwards
•
Transmit
•
Block distance protection receive
1MRK 505 406-UEN B
Section 5
Bay protection functions
Bay protection functions REB500
157
Technical manual
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