7.29
Date Code 20080213
Instruction Manual
SEL-351A Relay
Inputs, Outputs, Timers, and Other Control Logic
SEL
OGIC
Control Equation Variables/Timers
Figure 7.25
Dedicated Breaker Failure Scheme Created With SEL
OGIC
Control Equation Variables/Timers
Note that the above SEL
OGIC
control equation setting SV7 creates a seal-in
logic circuit (as shown in
) by virtue of SEL
OGIC
control equation
setting SV7 being set equal to Relay Word bit SV7 (SEL
OGIC
control equation
variable SV7):
SV7 =
(SV7 + IN101) * (50P1 + 50N1)
Optoisolated input
IN101
functions as a breaker failure initiate input. Phase
instantaneous overcurrent element 50P1 and neutral-ground instantaneous
overcurrent element 50N1 function as fault detectors.
Timer pickup setting SV6PU provides retrip delay, if desired (can be set to
zero). Timer dropout setting SV6DO holds the retrip output (output contact
OUT101
) closed for extra time if needed after the breaker failure initiate signal
(IN101) deasserts.
Timer pickup setting SV7PU provides breaker failure timing. Timer dropout
setting SV7DO holds the breaker failure trip output (output contact
OUT102
)
closed for extra time if needed after the breaker failure logic unlatches (fault
detectors 50P1 and 50N1 dropout).
suggests the option of having output contacts
OUT103
and
OUT104
operate as additional breaker failure trip outputs. This is done by
making the following SEL
OGIC
control equation settings:
OUT103 =
SV7T
(breaker failure trip)
OUT104 =
SV7T
(breaker failure trip)
Additional Settings
Example 2
The seal-in logic circuit in the dedicated breaker failure scheme in
can be removed by changing the SEL
OGIC
control equation setting SV7 to:
SV7 =
IN101 * (50P1 + 50N1)
If the seal-in logic circuit is removed, optoisolated input
IN101
(breaker failure
initiate) has to be continually asserted for a breaker failure time-out.
Timers Reset When
Power Is Lost,
Settings are
Changed, or Active
Setting Group Is
Changed
If power is lost to the relay, settings are changed (for the active setting group),
or the active setting group is changed, the SEL
OGIC
control equation
variables/timers are reset. Relay Word bits SV
n
and SV
n
T (
n
= 1–16) are reset
to logical 0 and corresponding timer settings SV
n
PU and SV
n
DO load up
again after power restoration, settings change, or active setting group switch.
Preceding
shows an effective seal-in logic circuit, created by use
of Relay Word bit SV7 (SEL
OGIC
control equation variable SV7) in SEL
OGIC
control equation SV7:
IN101
50P1
50N1
SV7
SV7T
SV6
SV6T
OUT101
(Retrip)
OUT102
(Breaker
Failure
Trip)
OUT103
OUT104
SV7PU
SV6PU
SV6D0
SV7D0
Содержание SEL-351A
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