Schweitzer Engineering Laboratories SEL-421-4 - Figure 5.72 Zone 3, 4, and 5 AB Loop Conventional Quadrilateral Phase-Distance Element Logic; Zone Time Delay

5.91
Date Code 20171021 Instruction Manual SEL-421 Relay
Protection Functions
Zone Time Delay
Figure 5.72 shows the logic of the Zone 3, 4, and 5 conventional quadrilateral
phase-distance element for the AB loop. Fault calculations for BC and CA faults
have similar logics.
Zone Time Delay
NOTE: If the relay is using a remote
data acquisition system, such as TiDL,
the operating times will be delayed by
1.5 ms. Use caution when setting the
relay coordination times to account
for this added 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
Figure 5.72 Zone 3, 4, and 5 AB Loop Conventional Quadrilateral Phase-Distance Element Logic
IABLFM
0.1 • I
NOM
F32P
R32P
DIRn = F
XABn
RABXn
OSBn
67QUBF
67QUBR
FSA
FSB
HSDAGF
HSDBGF
HSDAGR
HSDBGR
ILOP
SPO
MABDF
xABF
XPn
(setting)
—XPn
(setting)
—0.1 • I
NOM
MABDF
VPOLV
Phase Selection
ENX2AB
32QE