![Schweitzer Engineering Laboratories SEL-421-4 Instruction Manual Download Page 300](http://html.mh-extra.com/html/schweitzer-engineering-laboratories/sel-421-4/sel-421-4_instruction-manual_1216726300.webp)
5.140
SEL-421 Relay
Instruction Manual
Date Code 20171021
Protection Functions
Trip Logic
If an external reclosing relay is being used, control signals from the reclosing
relay will typically be used to control the SEL-421 single- and three-pole tripping
sequence. Another method is to use the TOP (Trip during Open-Pole) Relay
Word bit to select a three-pole trip after a single-pole trip in the SEL-421 by mak-
ing an appropriate setting for TOPD (Trip during Open-Pole Time Delay), and
then including the TOP Relay Word bit in the E3PT setting—see
.
External Recloser on page 6.10
and
External Recloser on page 6.26 in the
SEL-400 Series Relays Instruction Manual
for additional information. See
for an application example using the TOP Relay Word bit.
Timer setting TOPD determines the period during which any subsequent single-
pole trips are converted to a three-pole trip following the original single-pole trip.
To use this feature, include the Relay Word bit TOP in the E3PT setting.
Trip Output Signals
There are seven Relay Word bits (TPA1, TPA2, TPB1, TPB2, TPC1, TPC2, and
3PT) that you can program to drive contact outputs to trip circuit breakers. Relay
Word bits TPA
n
, TPB
n
, and TPC
n
are phase-selective tripping signals for con-
trolling the individual poles of the circuit breakers for single-pole tripping
schemes. Use Relay Word bit 3PT (Three-Pole Trip) to trip all three poles of both
circuit breakers.
Manual Trip Logic
The SEL-421 also has additional logic for manually tripping the circuit breakers.
Use SEL
OGIC
control equations BK1MTR and BK2MTR to trip the circuit
breakers manually. Use SEL
OGIC
control equations ULMTR1 and ULMTR2 to
unlatch manual trips for Circuit Breaker 1 and Circuit Breaker 2, respectively.
Trip Logic Settings and Relay Word Bits
The trip logic settings are shown in
, and the Relay Word bits are
. Some of the settings are only required in certain situations,
as noted.
Table 5.78
Trip Logic Settings (Sheet 1 of 2)
Setting
Prompt
Range
Default (5 A)
TR
Trip
SEL
OGIC
Equation Z1P OR Z1G OR M2PT OR Z2GT
TRCOMM
a
Communications-Assisted Trip
SEL
OGIC
Equation (Z2P OR Z2G) AND PLT02
TRCOMMD
Communications-Assisted Trip
SEL
OGIC
Equation NA
TRSOTF
b
Switch-Onto-Fault Trip
SEL
OGIC
Equation 50P1 OR Z2P OR Z2G
DTA
Direct Transfer Trip A-Phase
SEL
OGIC
Equation NA
DTB
Direct Transfer Trip B-Phase
SEL
OGIC
Equation NA
DTC
Direct Transfer Trip C-Phase
SEL
OGIC
Equation NA
BK1MTR
Breaker 1 Manual Trip—BK1
SEL
OGIC
Equation OC1 OR PB8_PUL
BK2MTR
c
Breaker 2 Manual Trip—BK2
SEL
OGIC
Equation NA
ULTR
Unlatch Trip
SEL
OGIC
Equation TRGTR
ULMTR1
Unlatch Manual Trip—BK1
SEL
OGIC
Equation NOT (52AA1 AND 52AB1 AND
52AC1)
ULMTR2
Unlatch Manual Trip—BK2
SEL
OGIC
Equation 1
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 ...