Sel SEL-421 - Zone Time Delay; Independent Zone Timing; Zones 3, 4, and 5 Mho Phase Distance Element Logic Diagram

R.1.61
Date Code 20111215 Reference Manual SEL-421 Relay
Protection Functions
Zone Time Delay
Figure 1.43 Zones 3, 4, and 5 Mho Phase Distance Element Logic Diagram
Zone Time Delay
The SEL-421 supports two philosophies of zone timing:
➤ Independent timing—the phase and ground distance elements
drive separate timers for each zone
➤ Common timing—the phase and ground distance elements both
drive a common timer
Independent Zone
Timing
Use Relay Word bits MnPT (Time-Delayed Zone Phase Distance Protection)
and ZnGT (Time-Delayed Zone Ground Distance Protection) to select
independent zone timing in SEL
OGIC control equation TR (Trip) (n = 1–5).
—
+
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bit
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Setting
32SPOF
IABL
DIRn := F
F32P
SPOA
SPOB
R32P
32SPOR
FSA
FSB
SPOC
VPOLV
ILOP
OSBA
OSBn
67QUBF
67QUBR
0.1 • I
nom
mAB < Znp
mAB < —Znp
MBCn
MABn
MnP
MCAn
mAB is the A-Phase-to-B-Phase Mho
Distance Calculation
Zones 3, 4, and 5 Phase Distance Logic
for AB Phase Pair is Similar to BC and CA.
n = 3, 4, or 5