![Schweitzer Engineering Laboratories SEL-421-4 Instruction Manual Download Page 383](http://html.mh-extra.com/html/schweitzer-engineering-laboratories/sel-421-4/sel-421-4_instruction-manual_1216726383.webp)
6.47
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Applications Examples
500 kV Parallel Transmission Lines With Mutual Coupling Example
Direct Tripping
Direct tripping is faster because the SEL-421 Relays at Station S do not have to
wait for the circuit breakers at Station R to single-pole trip first; that is, the
SEL-421 Relays at Station R single-pole direct transfer trip the SEL-421 Relays
at Station S during crossing country faults beyond the reach of Zone 1 ground-
distance protection at Station S.
Transmit Equations
TMB3A :=
TPA AND NOT 3PT
.
Transmit M
IRRORED
B
ITS
3A (SEL
OGIC
Equa-
tion)
TMB4A :=
TPB AND NOT 3PT
.
Transmit M
IRRORED
B
ITS
4A (SEL
OGIC
Equa-
tion)
TMB5A :=
TPC AND NOT 3PT
.
Transmit M
IRRORED
B
ITS
5A (SEL
OGIC
Equa-
tion)
Receive Equations
DTA :=
RMB3A
.
Direct Transfer Trip A-Phase (SEL
OGIC
Equation)
DTB :=
RMB4A
.
Direct Transfer Trip B-Phase (SEL
OGIC
Equation)
DTC :=
RMB5A
.
Direct Transfer Trip C-Phase (SEL
OGIC
Equation)
Example Completed
This completes the application example that describes how to set the SEL-421 for
communications-assisted protection of 500 kV parallel overhead transmission
lines with zero-sequence mutual coupling. Analyze your particular power system
to determine the appropriate settings for your application.
Relay Settings
lists all protective relay settings for this example. Settings used in this
example appear in boldface type.
Table 6.13
Settings for 500 kV Parallel TX Example (Sheet 1 of 7)
Setting
Prompt
Entry
General Global (Global)
SID
Station Identifier (40 characters)
MOSCOW - 500 kV
RID
Relay Identifier (40 characters)
SEL-421 Relay
NUMBK
Number of Breakers in Scheme (1, 2)
2
BID1
Breaker 1 Identifier (40 characters)
Circuit Breaker 1
BID2
Breaker 2 Identifier (40 characters)
Circuit Breaker 2
NFREQ
Nominal System Frequency (50, 60 Hz)
60
PHROT
System Phase Rotation (ABC, ACB)
ABC
DATE_F
Date Format (MDY, YMD, DMY)
MDY
FAULT
Fault Condition (SEL
OGIC
Equation)
50P1 OR 51S1 OR
Z2P OR Z2G OR
Z3P OR Z3G
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 ...