4.57
Date Code 20100129
Instruction Manual
SEL-751A Relay
Protection and Logic Functions
Reclose Supervision Logic
Unlatch Reclose Supervision Logic (Bottom of
)
. If the reclosing relay open interval time-
out condition is sealed-in, it stays sealed-in until
one
of the following occurs:
➤
The close logic output CLOSE (also see
) asserts
(Relay Word bit CLOSE = logical 1).
➤
The reclosing relay goes to the Lockout State (Relay Word bit
79LO = logical 1).
➤
The circuit breaker closes (52A = logical 1).
➤
The reclose initiation condition (79RI) makes a rising-edge
(logical 0 to logical 1) transition.
➤
SEL
OGIC
control equation setting 79CLS asserts
(79CLS = logical 1).
➤
The Reclose Supervision Limit Timer times out (Relay Word
bit RCSF = logical 1 for one processing interval).
The Reclose Supervision Limit Timer is inoperative if setting
79CLSD := OFF. With 79CLSD := OFF, reclose supervision condition 79CLS
is not time limited. When an open interval times out, reclose supervision
condition 79CLS is checked indefinitely until one of the other above unlatch
conditions comes true.
The unlatching of the sealed-in reclosing relay open interval time-out
condition by the assertion of SEL
OGIC
control equation setting 79CLS
indicates successful propagation of a reclosing relay open interval time-out
condition on to the close logic in
Settings Example 2 on page 4.59
EXAMPLE 4.5
Settings Example 1
Refer to the top of
and
.
SEL-751A relays are installed at both ends of a transmission line in a
high-speed reclose scheme. After both circuit breakers open for a line
fault, the SEL-751A(1) recloses circuit breaker 52/1 first, followed by
the SEL-751A(2) reclosing circuit breaker 52/2, after a synchronism
check across circuit breaker 52/2.
Figure 4.33
SEL-751A Relays Installed at Both Ends of a Transmission Line
in a High-Speed Reclose Scheme
SEL-751A (1)
Bus 1
Bus 2
52
1
52
2
IA, IB, IC
VA, VB, VC VS
SEL-751A (2)
IA, IB, IC
VA, VB, VC
VS
3-Phase
3-Phase
1-Phase
Summary of Contents for 751A
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