X
R
ArgDir
ArgNegRes
ZPE
ZRevPE
VA
ϕ
IA
en06000470_ansi.ep
ANSI06000470 V1 EN-US
Figure 106: Simplified characteristic for offset mho in reverse direction for A-to-ground fault
7.3.6.5 Simplified logic diagrams
GUID-22B4A410-6F8E-4569-A354-51A1F4951F79 v3
Distance protection zones
The design of the distance protection zones are presented for all measuring loops: phase-to-
ground as well as phase-to-phase.
Phase-to-ground related signals are designated by AG, BG and CG. The phase-to-phase signals are
designated by AB, BC and CA.
Fulfillment of two different measuring conditions is necessary to obtain the one logical signal for
each separate measuring loop:
• Zone measuring condition, which follows the operating equations described above.
• Group functional input signal (PHSEL), as presented in figure
107.
The ZMHPDIS (21) function block is used in the IED for each zone.
The PHSEL input signal represents a connection of six different integer values from Phase
selection with load encroachment function FMPSPDIS (21) within the IED, which are converted
within the zone measuring function into corresponding boolean expressions for each condition
separately. Input signal PHSEL is connected from FMPSPDIS (21) function output signal PHSCND.
1MRK 502 066-UUS B Section 7
Impedance protection
231
Technical manual
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