Schweitzer Engineering Laboratories SEL-311C - Figure 4.9 Negative-Sequence Voltage-Polarized Directional Element for Ground Distance and Residual Ground Overcurrent Elements

4.14
SEL-311C Relay Instruction Manual Date Code 20060320
Loss-of-Potential, CCVT Transient Detection, Load-Encroachment, and Directional Element Logic
Directional Control for Ground Distance and Residual Ground Overcurrent Elements
Note: 1 ∠ Z1L = One ohm at the positive-sequence line angle.
q From Figure 4.6; w from Figure 4.1; e from Figure 4.8; r to Figure 4.12.
Figure 4.9 Negative-Sequence Voltage-Polarized Directional Element
for Ground Distance and Residual Ground Overcurrent Elements
I
2
V
2
If Z2F Setting > 0, Forward Threshold = 1.25 • Z2F — 0.25 •
I
2
V
2
If Z2F Setting ≤ 0, Forward Threshold = 0.75 • Z2F — 0.25 •
Forward Threshold:
I
2
V
2
If Z2R Setting < 0, Reverse Threshold = 1.25 • Z2R + 0.25 •
I
2
V
2
If Z2R Setting ≥ 0, Reverse Threshold = 0.75 • Z2R + 0.25 •
Reverse Threshold:
Direction Element Characteristics
R2
X2
Forward Threshold
Reverse Threshold
Z2 PLANE
enable output
r
R32QG
(Reverse)
F32QG
(Forward)
q
50QF
Enable
Forward
Threshold
q
32QGE
w
ILOP
Reverse
Threshold
q
50QR
Re[V
2
•(I
2
•1
∠
Z1L)*]
|I
2
|
2
Z2 =
I
2
V
2
Relay
Word
Bits
Relay
Word
Bit
Relay
Word
Bits
Relay
Word
Bit
e
Best Choice Ground
Directional Logic