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7-8
Inputs, Outputs, Timers, and Other Control Logic
Date Code 20011205
SEL-311B Instruction Manual
Disable local control switches by “nulling out” all the label settings for that switch (see
Section 9: Setting the Relay
). The local bit associated with this disabled local control switch is
then fixed at logical 0.
Settings Examples
Local bits LB3 and LB4 might be used for manual trip and close functions. Their corresponding
local control switch position labels are set to configure the switches as OFF/MOMENTARY
switches:
Local Bit Label
Settings Function
LB3
NLB3 = MANUAL TRIP
trips breaker and drives reclosing relay to
lockout
CLB3 = RETURN
OFF position (“return” from MOMENTARY
position)
SLB3 =
ON position—not used (left “blank”)
PLB3 = TRIP
MOMENTARY position
LB4
NLB4 = MANUAL CLOSE closes breaker, separate from automatic
reclosing
CLB4 = RETURN
OFF position (“return” from MOMENTARY
position)
SLB4 =
ON position—not used (left “blank”)
PLB3 = CLOSE
MOMENTARY position
Figure 7.7 and Figure 7.8 show local control switches with example settings.
Figure 7.7: Configured Manual Trip Switch Drives Local Bit LB3
Local bit LB3 is set to trip in the following SEL
OGIC
control equation trip setting (see Figure 5.1
in
Section 5: Trip and Target Logic
):
TR = ... + LB3 + ...
To keep reclosing from being initiated for this trip, set local bit LB3 to drive the reclosing relay
to lockout for a manual trip (see
Section 6: Close and Reclose Logic
):
79DTL = ... + LB3
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