Load discrimination
The load area defined by the underimpedance parameters
RLoad and AngleLoad is taken into
account by starting and measuring characteristics. The distance function can only trip, if the
fault impedance lies within the underimpedance starting characteristic.
S4
S1
S2
S3
SR
Starting
R
X
18000010-IEC19000412-1-en.vsdx
IEC19000412 V1 EN-US
Figure 11: Load discrimination
The load impedance area is only formed when the underimpedance starter (UZ)
is in operation. It does not exist when starting is provided by the overcurrent
starter (OC).
Zero-sequence compensation of the protected line
The magnitude and phase-angle of the zero-sequence compensation factor are set individually
for each zone using parameters
k0 and k0Ang. The k0 factors are calculated from the positive-
sequence impedance ZL and the zero-sequence impedance Z0L of the line:
0
0
(
)
1 / 3
L
L
L
Z
Z
k
x
Z
0
0
1 / 3
(
) /
)
L
L
L
k
x Z
Z
Z
Range: 0 to 8 in steps of 0.01
0
0
0
arctan (
) / (
)
arctan (
/
)
L
L
L
L
L
L
k Ang
X
X
R
R
X
R
Range: -180° to +90° in steps of 0.01
1MRK 505 406-UEN B
Section 5
Bay protection functions
Bay protection functions REB500
45
Technical manual
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