Schweitzer Engineering Laboratories SEL-700G Series, Instruction Manual

Page: 216 / 824

4.110
SEL-700G Relay Instruction Manual Date Code 20170814
Protection and Logic Functions
Group Settings (SET Command)
Figure 4.77 Negative-Sequence Voltage-Polarized Directional Element for
Residual-Ground Overcurrent Elements
q
From Table 4.28
w
To Figure 4.81
e
From Figure 4.74
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
DIRQGE is highest
RDIRQG
(Reverse)
FDIRQG
(Forward)
Best Choice
Ground
Directional
Logic
50QF
Enable
Forward
Threshold
DIRQGE
Reverse
Threshold
50QR
e
Re[V
2
•(I
2
•1
∠
Z1ANG)*]
|I
2
|
2
Z2 =
I
2
V
2
Relay
Word
Bits
Relay
Word
Bit
Relay
Word
Bit
Relay
Word
Bit
choice that is asserted
1
2
3
3