Schweitzer Engineering Laboratories SEL-751 - Figure 4.38 Positive-Sequence Voltage-Polarized Directional Element for Phase Overcurrent Elements

4.51
Date Code 20170927 Instruction Manual SEL-751 Relay
Protection and Logic Functions
Group Settings (SET Command)
q From Figure 4.54; w from Figure 4.37; e from Figure 4.73; r to Figure 4.39.
Figure 4.38 Positive-Sequence Voltage-Polarized Directional Element for
Phase Overcurrent Elements
LOP
ZLOAD
Load Condition
Loss-of-Potential
VNOM = OFF
1
3
50PDIRP • √3
50PDIR
|I
A
—I
B
|
|I
B
—I
C
|
|I
C
—I
A
|
VPOLV
RDIRQ
FDIRQ
Settin
g
[fixed at (
p
hase channel nominal ratin
g
) • (0.1) when enable settin
g
ELOAD = Y]
FDIRP
(Forward)
RDIRP
(Reverse)
[90° + Z1ANG] > ∠Z
1
> [—90° + Z1ANG]
Z1ANG
X
1
(90°)
(270°)
(0°)
(180°)
R
1
Forward
Reverse
Pos.-Seq. Polarizing Voltage Present
Neg.-Seq. Dir. Element Has Priority
Neg.-Seq. Dir. Element Has Priority
Relay
Word
Bits
Relay
Word
Bits
All internal phase-to-phase distance-type elements forward
All internal phase-to-phase distance-type elements reverse
2
1
2
4
NOTE: The positive-sequence
voltage-polarized directional
element uses positive-sequence
memory voltage as the polarizing
voltage.