X
a
a>b
b
IDirPU
polMethod=Voltage
polMethod=Dual
OR
FORWARD_Int
REVERSE_Int
BLOCK
STAGE1_DIR_Int
0.6
X
0.4
AND
STAGE3_DIR_Int
STAGE4_DIR_Int
STAGE2_DIR_Int
OR
PUREV
VPolMin
IPolMin
AngleRCA
T
F
0.0
X
T
F
RNPol
XNPol
0.0
D
i
r
e
c
t
i
o
n
a
l
C
h
a
r
a
c
t
e
r
i
s
t
i
c
FWD
RVS
AND
AND
AND
PUFW
FORWARD_Int
REVERSE_Int
AND
ANSI07000067-4-en.vsd
|
|
VPol
VIPol
I3PDIR
VTPol
IopDir
Complex
Number
a
a>b
b
IPol
T
F
0.0
polMethod=Current
OR
ANSI07000067 V4 EN-US
Figure 256: Simplified logic diagram for directional supervision element with integrated directional
comparison step
8.4.7.9 Second harmonic blocking element
M13941-200 v6
A harmonic restrain of four step residual overcurrent protection function EF4PTOC can be chosen
for each step by a parameter setting
HarmRestrainx
. If the ratio of the 2nd harmonic component in
relation to the fundamental frequency component in the residual current exceeds the preset level
(defined by parameter
2ndHarmStab
) then ST2NDHRM function output signal is set to logical
value one and harmonic restraining feature to the function block will be applicable.
Blocking from 2nd harmonic element activates if all three criteria are satisfied:
1. Current fundamental frequency component >
IMinOpHarmBlk
2. Current second harmonic component >
IMinOpHarmBlk
3. Ratio of the 2nd harmoinc component in relation to the fundamental frequency component in
the residual current exceeds the preset level defined parameter
2ndHarmStab
setting
If all the above three conditions are fulfilled then ST2NDHRM function output signal is set to
logical value one and harmonic restraining feature to the function block is applicable.
Section 8 1MRK 502 066-UUS B
Current protection
486
Technical manual
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