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Determination of
the Faulty Phase
2.26.2 Setting Hints
General
Displacement
Voltage
7UM62 Manual
C53000-G1176-C149-3
In addition to this, a supplementary function serves to determine the faulty phase. As
the phase-earth-voltage in the faulty phase is less than in the two remaining phases
and as the voltage even increases in the latter ones, the faulty phase can be
determined by determining the smallest phase-earth voltage in order to generate a
corresponding result as fault message.
5002 U0>
&
5003 3I0>
&
5004 DIR. ANGLE
&
FNo. 05173
>S/E/F BLOCK
FNo. 05176
>S/E/F Iee off
OR
non-direct. only U0
directional
non-dir. with U0 & I0
"1"
0150 S/E/F PROT.
Figure 2-87
Logic Diagram of the 90%–Stator Earth Fault Protection
The 90% stator earth fault protection is only effective and accessible if it has been set
during the configuration of the protection functions at address 0150 S/E/F PROT. =
directional; non-dir. U0 or non-dir. U0&I0. If non–dir. U0 was
selected, the parameters concerning the earth current are ineffective. If one of the
options directional or non–dir. U0&I0 was selected, the parameters
concerning the earth current are accessible. For machines in busbar connection, one
of the latter options must set as a differentiation between the power system earth fault
and the machine earth fault is only possible by way of the earth current. If the 90%
stator earth fault protection is used as "earth differential protection", address 0150
S/E/F PROT. = non-dir. U0&I0 is selected. Set Disabled if the function is not
required. Address 5001 S/E/F PROT. is used to switch the function ON or OFF, or to
block only the trip command (Block Relay).
The criterion for the inception of an earth fault in the stator circuit is the occurrence of
a neutral displacement voltage. Exceeding the setting value 5002 U0> therefore
represents the pickup for this protection.
The setting must be chosen such that the protection does not pick up during
operational asymmetries. This is particularly important for machines in busbar
connection since all voltage asymmetries of the network affect the voltage system of
the machine. The pickup value should be at least twice the value of the operational
asymmetry. A value of 5% to 10% of the full displacement value is normal.
90–%–Stator Earth Fault Protection (ANSI 59N, 64G, 67G)
FNo. 05186
U0> picked up
FNo. 05188
&
3I0> picked up
&
&
OR
&
OR
FNo. 05182
S/E/F BLOCKED
FNo. 05193
S/E/F TRIP
FNo. 05187
U0> TRIP
5005 T S/E/F
5005 T S/E/F
FNo. 05194
&
SEF Dir Forward
Tripping
matrix
TMin
TRIP CMD
181
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