can be chosen very low. As it is required to detect ground faults in the transformer
winding, close to the neutral point, values down to the minimum setting possibilities
can be chosen. However, one must consider zero-sequence currents that can occur
during normal operation of the power system. Such currents can be due to un-
transposed lines.
In case to protection of transformer windings not feeding residual current at external
ground faults a fast lowcurrent step can be acceptable.
3.7.4.3 Setting parameters
Table 95: EF4PTOC (51N67N) Group settings (basic)
Name Values (Range) Unit Step Default Description
Operation Disabled
Enabled
- - Disabled Disable/Enable Operation
IBase 1 - 99999 A 1 3000 Base value for current settings
VBase 0.05 - 2000.00 kV 0.05 400 Base value for voltage settings
AngleRCA -180 - 180 Deg 1 65 Relay characteristic angle (RCA)
polMethod Voltage
Current
Dual
- - Voltage Type of polarization
VPolMin 1 - 100 %VB 1 1 Minimum voltage level for polarization in % of
VBase
IPolMin 2 - 100 %IB 1 5 Minimum current level for polarization in % of
IBase
RNPol 0.50 - 1000.00 ohm 0.01 5.00 Real part of source Z to be used for current
polarisation
XNPol 0.50 - 3000.00 ohm 0.01 40.00 Imaginary part of source Z to be used for
current polarisation
INDirPU 1 - 100 %IB 1 10 Residual current level for directional element
in % of IBase
2ndHarmStab 5 - 100 % 1 20 Second harmonic restrain operation in % of
IN magnitude
BlkParTransf Disabled
Enabled
- - Disabled Enable blocking at parallel transformers
Use_PUValue ST1
ST2
ST3
ST4
- - ST4 Current pickup blocking at parallel transf
(step1, 2, 3 or 4)
SOTF Disabled
SOTF
UnderTime
SOTF&UnderTime
- - Disabled SOTF operation mode (Off/SOTF/Undertime/
SOTF&Undertime)
SOTFSel Open
Closed
CloseCommand
- - Open Select signal that shall activate SOTF
Table continues on next page
1MRK504116-UUS C Section 3
IED application
435
Application manual
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