![Schweitzer Engineering Laboratories SEL-421-4 Instruction Manual Download Page 253](http://html.mh-extra.com/html/schweitzer-engineering-laboratories/sel-421-4/sel-421-4_instruction-manual_1216726253.webp)
5.93
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Functions
Instantaneous Line Overcurrent Elements
Instantaneous Line Overcurrent Elements
The SEL-421 calculates instantaneous overcurrent elements for phase (P), resid-
ual ground (G, vector sum of I
A
, I
B
, and I
C
), and negative-sequence (Q) quanti-
ties. Four levels of instantaneous elements are available named 50P1–50P4,
50Q1–50Q4, and 50G1–50G4, as shown in
through
, with
through
.
These overcurrent elements always operate on the line current (IW terminal cur-
rent or the sum of the IW and IX terminal currents) according to the global set-
ting LINEI (Line Current Source). The instantaneous overcurrent elements are
inputs to the instantaneous directional (67P
n
, 67Q
n
, 67G
n
, where
n
= 1–4) and
definite-time directional overcurrent elements (67P
n
T, 67Q
n
T, 67G
n
T, where
n
= 1–4). See
for details on the directional control
option. Note that the 67P
n
and 67P
n
T elements are not directionally controlled
by the built-in logic; they can be made directional through the use of torque con-
trol settings 67P1TC–67P4TC.
Figure 5.73
Zone Timers
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Z1D
Z1T
Z1PT
Z1GT
Z1P
Z1G
Suspend Timing
Zone 1 Delay Timer Logic
0
CYC
Z1PD
0
CYC
Z1GD
0
CYC
Z2D
Z2T
Z2PT
Z2GT
Z2P
Z2G
Suspend Timing
Zone 2 Delay Timer Logic
0
CYC
Z2PD
0
CYC
Z2GD
0
CYC
Z3D
Z3T
Z3PT
Z3GT
Z3P
Z3G
Suspend Timing
Zone 3 Delay Timer Logic
0
CYC
Z3PD
0
CYC
Z3GD
0
CYC
Z4D
Z4T
Z4PT
Z4GT
Z4P
Z4G
Suspend Timing
Zone 4 Delay Timer Logic
0
CYC
Z4PD
0
CYC
Z4GD
0
CYC
Z5D
Z5T
Z5PT
Z5GT
Z5P
Z5G
Suspend Timing
Zone 5 Delay Timer Logic
0
CYC
Z5PD
0
CYC
Z5GD
0
CYC
Summary of Contents for SEL-421-4
Page 6: ...This page intentionally left blank ...
Page 14: ...This page intentionally left blank ...
Page 30: ...This page intentionally left blank ...
Page 104: ...This page intentionally left blank ...
Page 128: ...This page intentionally left blank ...
Page 536: ...This page intentionally left blank ...
Page 584: ...This page intentionally left blank ...
Page 616: ...This page intentionally left blank ...
Page 696: ...This page intentionally left blank ...
Page 750: ...This page intentionally left blank ...
Page 755: ...Instruction Manual PM400 01 NB SEL 400 Series Relays Instruction Manual 20171006 ...
Page 776: ...This page intentionally left blank ...
Page 932: ...This page intentionally left blank ...
Page 976: ...This page intentionally left blank ...
Page 1024: ...This page intentionally left blank ...
Page 1038: ...This page intentionally left blank ...
Page 1064: ...This page intentionally left blank ...
Page 1128: ...This page intentionally left blank ...
Page 1206: ...This page intentionally left blank ...
Page 1316: ...This page intentionally left blank ...
Page 1350: ...This page intentionally left blank ...
Page 1464: ...This page intentionally left blank ...
Page 1468: ...This page intentionally left blank ...
Page 1492: ...This page intentionally left blank ...
Page 1518: ...This page intentionally left blank ...