Schweitzer Engineering Laboratories SEL-311C - Figure 4.10 Zero-Sequence Voltage-Polarized Directional Element for Ground Distance and Residual Ground Overcurrent Elements

4.15
Date Code 20060320 Instruction Manual SEL-311C Relay
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 zero-sequence line angle.
q From Figure 4.7; w from Figure 4.1; e from Figure 4.8; r to Figure 4.12.
Figure 4.10 Zero-Sequence Voltage-Polarized Directional Element
for Ground Distance and Residual Ground Overcurrent Elements
I
0
V
0
If Z0F Setting > 0, Forward Threshold = 1.25 • Z0F — 0.25 •
I
0
V
0
If Z0F Setting ≤ 0, Forward Threshold = 0.75 • Z0F — 0.25 •
Forward Threshold:
I
0
V
0
If Z0R Setting < 0, Reverse Threshold = 1.25 • Z0R + 0.25 •
I
0
V
0
If Z0R Setting ≥ 0, Reverse Threshold = 0.75 • Z0R + 0.25 •
Reverse Threshold:
Direction Element Characteristics
R0
X0
Forward Threshold
Reverse Threshold
Z0 PLANE
enable output
r
R32V
(Reverse)
F32V
(Forward)
q
50GF
Enable
Forward
Threshold
q
32VE
w
ILOP
Reverse
Threshold
q
50GR
Re[3V
0
•(I
G
•1
∠
Z0L)*]
|I
G
|
2
Z0 =
I
G
(residual)
(I
G
= 3I
0
)
3V
0
Relay
Word
Bits
Relay
Word
Bit
Relay
Word
Bits
Relay
Word
Bit
e
Best Choice Ground
Directional Logic