MODEL VARIATIONS COVERED BY THIS INSTRUCTION MANUAL
SEL offers several optional variations of the SEL-221F relay logic. While this introduction
includes a short description of each model variation, the remainder of the instruction manual
pertains only to the standard SEL-221F relay and the -1 variation. Please consult the
information sticker on the relay rear panel if you are unsure of the relay model number.
SEL-221F Relay
The basic SEL-221F relay employs each feature outlined in the preceding Relay Overview.
SEL-221F-1 Relay
SEL-22lF-1 relay 79RS timer begins timing after the 52A input to the relay is energized
following a close. This is different from the SEL-221F relay which starts the 79RS timer
when the relay CLOSE output contact asserts.
To illustrate the benefits of this modification, please refer to the system in Figure 1.1, on the
following page. The SEL-221F-1 relay at Bus C is being used for line protection. Backup
protection energizing the IN1 input permits use of relay reclosing functions for trips generated
by transformer bank backup protection. Breaker 1 is set up to test the line after 5 seconds
with hot bus/dead line supervision with the 79RS timer set for 20 seconds. Breaker 2 is set
up for synch-check supervised closure with the 79RS timer also set for 20 seconds. Assume
the synch check timer is set for five seconds. The MOD is setup for hot line/dead bus
reclosure in 35 seconds (25 seconds after Breaker 2 closes).
For the system shown, consider a permanent fault on the transformer side of the motor
operated disconnect at Station C. Breaker 1, Breaker 2, and the MOD should trip for this
fault. The MOD is blocked from immediate tripping by an overstress scheme and trips when
the line is dead. Five seconds after the MOD opens, Breaker 1 recloses successfully. Five
seconds alter Breaker 1 energizes the line, Breaker 2 closes. Twenty-five seconds later, the
MOD at Bus C recloses into the fault, which causes Breaker 1, Breaker 2, and the MOD to
trip again. Since the trips at Breakers 1 and 2 occurred after their respective 79RS timers had
expired, these breakers are permitted to reclose. However, the MOD trip occurred before the
79RS timer reset, which locks out the MOD.
Caution:
The 79RS timer in the SEL-221F-1 relay no longer blocks a standing close
from the relay if the 52A input is never energized following a reclose.
1-2
Introduction
SEL-221F, -1 Instruction Manual
Date Code 920508
Summary of Contents for SEL-221F
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Page 110: ...Example Event Report 2 4 12 Event Reporting SEL 221F 1 Instruction Manual Date Code 930830 ...
Page 158: ...SETTINGS SHEET FOR SEL 221F RELAY PAGE 2 OF 6 DATE Date Code 921110 ...
Page 160: ...SETTINGS SHEET PAGE 4 OF 6 FOR SEL 221F RELAY DATE Date Code 930601 ...
Page 161: ...SETTINGS SHEET PAGE 5 OF 6 FOR SEL 221F RELAY DATE Date Code 961208 ...
Page 229: ...SEL 200 Series Relay Main Board Troubleshooting Test Points and Jumper Locations ...