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5.84
SEL-421 Relay
Instruction Manual
Date Code 20171021
Protection Functions
Mho Phase-Distance Elements
shows the Zone 3, 4 and 5 phase-distance element logic. Other fault
calculations (BC, CA) have similar logic. In
, Output Z
n
P is the OR
combination of the following Zone
n
(
n
= 3, 4, 5) elements (ØØ = AB, BC, CA):
➤
Conventional mho elements (MØØ
n
)
➤
Conventional quadrilateral elements (XØØ
n
)
Figure 5.65
Zones 3, 4, and 5 Mho Phase-Distance Element Logic Diagram
—
+
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Setting
32SPOF
IABLFM
DIRn := F
F32P
SPOA
SPOB
R32P
32SPOR
SPOC
VPOLV
ILOP
OSBA
OSBn
67QUBF
67QUBR
—
+
—ZnMP
(setting)
—
+
ZnMP
(setting)
+
—
IABL
—0.1 • I
NOM
+
—
0.1 • I
NOM
mABF
FSA
FSB
MABDF
MABn
MBCn
XBCn
XCAn
MCAn
XABn
Relay
Word
Bit
ZnP
Relay
Word
Bits
MnP
Summary of Contents for SEL-421-4
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