6.10.2.6 Simplified logic diagrams
Figure 110 presents schematically the creation of the phase-to-phase and phase-to-
ground operating conditions. Consider only the corresponding part of measuring and
logic circuits, when only a phase-to-ground or phase-to-phase measurement is
available within the IED.
ANSI09000149-2-en.vsd
AND
AND
AND
Bool to
integer
DLECND
STPG
STPP
IRELPG
IRELPP
BLOCK
AND
Load encroachment block
0
20ms
0
10ms
0
15ms
0
15ms
03I IMinPUPG<
0 max
3 0 _
3
100
I BLK PP
I Iph< ×
03 0.5I IMinPUPG³ ×
0
3 0 _
3
100
max
I Enable PG
I Iph³ ×
ANSI09000149 V2 EN
Figure 178: Phase-to-phase and phase-to-ground operating conditions (residual
current criteria)
A special attention is paid to correct phase selection at evolving faults. A PHSEL
output signal is created as a combination of the load encroachment characteristic and
current criteria, refer to figure 110. This signal can be configured to STCND functional
input signals of the distance protection zone and this way influence the operation of the
phase-to-phase and phase-to-ground zone measuring elements and their phase related
pickup and tripping signals.
Figure
111 presents schematically the composition of non-directional phase selective
signals NDIR_A (B or C). Internal signals ZMn and ZMmn (m and n change between
A, B and C according to the phase) represent the fulfilled operating criteria for each
separate loop measuring element, that is within the characteristic.
1MRK505222-UUS C Section 6
Impedance protection
339
Technical reference manual
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