Schweitzer Engineering SEL-351P - Page 238

4-16 Loss-of-Potential, Load Encroachment, and Directional Element Logic Date Code 990430
SEL-351P Manual Técnico
Z
0
= Re[3V
0
(I
N
•1 ∠ Z
0
l)*]
F32N
Forward
Threshold
Reverse
Threshold
R32N
3V
0
I
N
ELOP=Y or Y1
Enable
LOP
32NE
50NR
50NF
to Figure
4.13
Note: 1 ∠ Z0L = One OHM At The Zero-Sequence Line Angle
If Z0F Setting
≤ 0, Forward Threshold = 0.75 • Z0F - 0.25
If Z0F Setting > 0, Forward Threshold = 1.25 • Z0F - 0.25
If Z0R Setting < 0, Reverse Threshold = 1.25 • Z0R + 0.25
If Z0R Setting
≥ 0, Reverse Threshold = 0.75 • Z0R + 0.25
Direction Element Characteristics
Reverse Threshold
Forward Threshold
Forward Threshold:
Reverse Threshold:
Z0 PLANE
X0
R0
0
0
I
V
0
I
0
V
I
0
0
V
V
I
0
0
|I
N
|
2
Relay
Word
Bits
Relay
Word
Bits
Setting
DWG: M351R155
Relay
Word
Bit
Relay
Word
Bit
(Reverse)
(Forward)
from
Figure 4.1
Figure SECTION 4: .11: Zero-Sequence Voltage-Polarized, Neutral-Current
Directional Elements for Neutral Ground Overcurrent Elements