0.85 1 0.15 1
Re
V A V AM
AngDir Ang AngNeg s
IA
× + ×
- < <
EQUATION1618 V1 EN (Equation 49)
where:
AngDir
is the setting for the lower boundary of the forward directional characteristic, by default set to
15 (= -15 degrees) and
AngNegRes
is the setting for the upper boundary of the forward directional characteristic, by default set
to 115 degrees, see figure 135.
V1
A
is positive sequence phase voltage in phase A
V1
AM
is positive sequence memorized phase voltage in phase A
I
A
is phase current in phase A
The setting of AngDir and AngNegRes is by default set to 15 (= -15) and 115 degrees
respectively (see figure 135) and it should not be changed unless system studies have
shown the necessity.
ZDMRDIR (21D) gives a binary coded signal on the output STDIRCND depending on
the evaluation where FWD_A=1 adds 1, REV_A=1 adds 2, FWD_B=1 adds 4 etc.
R
X
AngDir
AngNegRes
en05000722_ansi.vsd
ANSI05000722 V1 EN
Figure 135: Setting angles for discrimination of forward and reverse fault
1MRK505222-UUS C Section 6
Impedance protection
269
Technical reference manual
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