Sel 551 - Table 3.5 Relay Word Bit and Front-Panel Correspondence to Reclosing Relay States

3.23
Date Code 20110408 Instruction Manual SEL-551 Relay
Relay Elements and Logic
Reclosing Relay
The reclosing relay is in one and only one of these states (listed in Table 3.5)
at any time. When in a given state, the corresponding Relay Word bit asserts to
logical 1, and the LED illuminates. Automatic reclosing only takes place
when the relay is in the Reclose Cycle State.
Lockout State
The reclosing relay goes to the Lockout State if any one of the following
occurs:
➤ The shot counter is equal to or greater than last shot at time of
reclose initiation (e.g., all automatic reclosing attempts are
unsuccessful—see Figure 3.16).
➤ Reclose initiation is unsuccessful because of SELOGIC control
equation setting 79RIS [see Reclose Initiate and Reclose
Initiate Supervision Settings (79RI and 79RIS, Respectively) on
page 3.27)].
➤ The circuit breaker opens without reclose initiation (e.g., an
external trip).
➤ The shot counter is equal to or greater than last shot, and the
circuit breaker is open [e.g., the shot counter is driven to last
shot with SEL
OGIC control equation setting 79DLS while open
interval timing is in progress. See Drive-to-Lockout and Drive-
to-Last Shot Settings (79DTL and 79DLS, Respectively) on
page 3.29)].
➤ The close failure timer (setting CFD) times out (see
Figure 3.14).
➤ SELOGIC control equation setting 79DTL = logical 1 [see
Drive-to-Lockout and Drive-to-Last Shot Settings (79DTL and
79DLS, Respectively)].
➤ Open Command (OPE) is executed and SELOGIC control
equation setting 79RI = TRIP + …). [Early SEL-551 firmware
versions do not have this feature (see Appendix A: Firmware
and Manual Versions). To effectively incorporate this feature
into these firmware versions, set SEL
OGIC control equation
setting 79DTL = OC + … (and 79RI = TRIP + …). Relay Word
bit OC asserts to logical 1 for 1/8 cycle when the Open
Command is executed (see Table 4.3 and Table 4 .4). See OPE
Command (Open) on page 5.23.]
➤ A new reclose initiation occurs while the reclosing relay is
timing on an open interval (e.g., flashover in the tank while
breaker is open).
Table 3.5 Relay Word Bit and Front-Panel Correspondence to Reclosing
Relay States
Reclosing Relay State
Corresponding
Relay Word Bit
Corresponding
Front-Panel LED
Reset 79RS RS
Reclose Cycle 79CY None
Lockout 79LO LO