Sel SEL-421 - Zones 3, 4, and 5 Mho Ground Distance Element Logic Diagram

R.1.53
Date Code 20111215 Reference Manual SEL-421 Relay
Protection Functions
Mho Ground Distance Elements
Figure 1.37 Zones 3, 4, and 5 Mho Ground Distance Element Logic Diagram
32SPOF
DIRn := F
MAGn
MBGn
ZnG
MCGn
XAGn
XBGn
XCGn
32GF
OSBn
OSBA
FSA
SPO
SPOA
32GR
32SPOR
3PO
ILOP
VPOLV
mAGF is the Forward A-Phase-to-Ground Mho Distance
Calculation.
mAGR is the Reverse A-Phase-to-Ground Distance
Calculation.
Zone 3, 4, and 5 Mho Ground Distance Logic for
A-Phase. B- and C-Phase Logic Is Similar.
n = 3, 4, or 5
Setting
Relay
Word
Bit
Relay
Word
Bits
Relay
Word
Bit
Relay
Word
Bit
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
—
+
—
+
IAL
IGL
mAGF < ZnMG
mAGR < -ZnMG
0.1 • I
nom