Sel 751A - Reclose Supervision Logic; Close Failure Logic; Figure 4.31 Reclose Supervision Logic (Following Open Interval Time-Out)

4.54
SEL-751A Relay Instruction Manual Date Code 20100129
Protection and Logic Functions
Reclose Supervision Logic
Close Failure Logic
Set the close failure delay (setting CFD) equal to highest breaker close time
plus a safety margin. If the breaker fails to close, the Relay Word CF will
assert for 1/4 cycle. Use the CF bit as desired.
Reclose Supervision Logic
Note that one of the inputs into the close logic in Figure 4.30 is:
Reclosing Relay Open Interval Time-Out (qualified by 79CLS)
This input into the close logic in Figure 4.30 is the indication that a reclosing
relay open interval has timed out (see Figure 4.32), a qualifying condition
(SEL
OGIC control equation setting 79CLS) has been met, and thus automatic
reclosing of the circuit breaker should proceed by asserting the CLOSE Relay
Word bit to logical 1. This input into the close logic in Figure 4.30 is an output
of the reclose supervision logic in the following Figure 4.31.
q To Figure 4.30
Figure 4.31 Reclose Supervision Logic (Following Open Interval Time-Out)
Operation of Reclose Supervision Logic if
timer setting 79CLSD is set:
79CLSD = 0
The above logic satisfies most
applications.
Reclose Supervision
Reclosing
Relay Open
Interval Timeout
(qualified by 79CLS)
Reclosing
Relay Open
Interval
Timeout
(qualified
by 79CLS)
Reclose Initiate
(If setting 79CLSD = OFF,
the Reclose Supervision Limit
Timer is inoperative and does
not time limit the wait for the
Reclose Supervision condition,
79CLS, to assert to logical 1)
Reclosing
Relay Open
Interval
Timeout
79RI
79CLSD = OFF
Lockout
Reclose
Supervision
Limit Timer
Reclose Supervision
CLOSE
79LO
79CLSD
0
SELOGIC
Setting
52A
SELOGIC
Settings
79CLS
SELOGIC
Setting
RCSF
Relay
Word
Bit
RCSF
Relay
Word
Bit
Relay
Word
Bits
79CLS
Reclosing
Relay Open
Interval
Timeout
Rising-Edge
Detect
Reclose Supervision
Failure
Pulses (logical 1) for one
processing interval and
drives the reclose state
to lockout if Reclose
Supervision Limit Timer
times out.
Reclose Supervision Failure
Pulses (logical 1) for one
processing interval and
drives the reclose state to
lockout if SEL
OGIC control
equation setting 79CLS is not
asserted to logical 1 at the
instant a reclosing relay open
interval timer times out.
Operation of Reclose Supervision Logic if
timer setting 79CLSD is set:
79CLSD ≠ 0 (e.g., 79CLSD = 60)
The logic below is used only in a few,
unique applications.
q
q