Susceptance reverse
This setting should be set based on the value of the maximum ground-fault current
produced by the feeder (considering possible feeder topology changes) with a security
margin. This ensures that the admittance operating point stays inside the "Box"-
characteristics during outside fault. The recommended security margin should not be
lower than 1.5.
Susceptance reverse: - (10 A * 1.5)/ (15 kV/sqrt(3)) = -1.73 mS
Conductance reverse
This setting is used to complete the non-directional characteristics by closing the "Box"-
characteristic. In order to keep the shape of the characteristic reasonable and to allow
sufficient margin for the admittance operating point during outside fault, it is
recommended to use the same value as for setting Susceptance reverse.
Conductance reverse = -1.73 mS
‐5 ‐4 ‐3 ‐2 ‐1
0
12345
‐5
‐4
‐3
‐2
‐1
0
1
2
3
4
5
Bo(mS)
Go(mS)
Backwardfault:
Yo≈‐ j*1.15mS
Forwardfault,
Yo≈1.73+j*BomS
‐5 ‐4 ‐3 ‐2 ‐1012345
‐5
‐4
‐3
‐2
‐1
0
1
2
3
4
5
Bo(mS)
Go(mS)
‐ 1.73mS
‐ 1.73mS
+0.1mS
TRIP TRIP
TRIP TRIP
+0.35mS
GUID-1E9D7C77-63A6-40BF-AF9D-60CF77EA8940 V1 EN
Figure 191: Admittances of the example
4.2.4.7 Signals
Table 379: 21YN Input signals
Name
Type Default Description
IG SIGNAL 0 Residual current
VG SIGNAL 0 Residual voltage
BLOCK BOOLEAN 0=False Block signal for activating the blocking mode
RELEASE BOOLEAN 0=False External trigger to release neutral admittance protection
Section 4 1MAC059074-MB A
Protection functions
398 615 series ANSI
Technical Manual
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