U.4.57
Date Code 20020501
User’s Guide
SEL-421/SEL-421-1 Relay
Basic Relay Operations
Operating the Relay Inputs and Outputs
Figure 4.52
Front-Panel LOCAL CONTROL Screens.
Setting Outputs for
Tripping and Closing
To actuate power system circuit breakers, you must configure the SEL-421
Relay control outputs to operate the trip bus and close bus. The relay uses
internal logic and SEL
OGIC
control equations to activate the control outputs.
Trip Output Signals
The SEL-421 Relay is capable of single-pole tripping and three-pole tripping.
There are many Relay Word bits (e.g., TPA1, TPA2, RTA1, and 3PT) that you
can program to drive control outputs to trip circuit breakers. See
Protection Functions in the Reference Manual
for complete information on
tripping equations and settings. For target illumination at tripping, see
Section 5: Front-Panel Operations in the User’s Guide
.
Close Output Signals
The SEL-421 Relay features an automatic recloser for single circuit breaker
and two circuit breaker applications. The relay provides as many as two
single-pole and four three-pole reclose shots. See
Synchronism Check in the Reference Manual
for more information. Close the
circuit breakers using Relay Word bits BK1CLS and BK2CLS for Circuit
Breaker 1 and Circuit Breaker 2, respectively.
Assigning Control Outputs for Tripping and Closing
The procedure in the following steps shows a method for setting the relay to
operate the trip bus and the close bus at a typical substation. Relay factory
defaults assign control outputs OUT101 and OUT102 to the trip bus and
OUT103 to the close bus for a three-pole tripping circuit breaker. This
procedure assigns an additional close output at OUT106.
1 ON
0 OFF
5 MVA XFMR Fans
1
0
METER
EVENTS
BREAKER MONITOR
RELAY ELEMENTS
LOCAL CONTROL
SET/SHOW
RELAY STATUS
VIEW CONFIGURATION
DISPLAY TEST
RESET ACCESS LEVEL
MAIN MENU
LOCAL CONTROL
--BREAKER CONTROL--
5 MVA XFMR Fans
--OUTPUT TESTING--
Summary of Contents for SEL-421
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