X
R
ArgDir
ArgNegRes
ZPE
ZRevPE
VA
ϕ
IA
en06000470_ansi.ep
ANSI06000470 V1 EN
Figure 125: Simplified characteristic for offset mho in reverse direction for A-to-
ground fault
6.4.2.5 Simplified logic diagrams
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
126.
One type of function block, ZMHPDIS (21) are used in the IED for zone 1 - 5.
Section 6 1MRK505222-UUS C
Impedance protection
254
Technical reference manual
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