U.4.62
SEL-421 Relay User’s Guide Date Code 20090715
Basic Relay Operations
Operating the Relay Inputs and Outputs
c. Select 5 MVA XFMR Fans on the LOCAL CONTROL screen
as shown in Figure 4.54.
d. Press {ENT} to see the last screen of Figure 4.54.
e. Highlight
1 ON and press {ENT}.
The graphical local control handle moves to the
1 position. At this time, the transformer fans will begin
running.
Figure 4.54 Front-Panel LOCAL CONTROL Screens
Setting Outputs for
Tripping and Closing
To actuate power system circuit breakers, you must configure the SEL-421
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 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 Section 1:
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.
Close Output Signals
The SEL-421 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 Section 2: Auto-Reclosing and
Synchronism Check in the Reference Manual for more information.
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--
Courtesy of NationalSwitchgear.com
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