Date Code 20001006 Inputs, Outputs, Timers, and Other Control Logic 7-9
SEL-351 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.
Factory Settings Examples
Local bits LB3 and LB4 are used in a few of the factory SELOGIC Control Equation settings 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
Following Figure 7.9 and Figure 7.10 show local control switches with factory settings.
Figure 7.9: Configured Manual Trip Switch Drives Local Bit LB3
Local bit LB3 is set to trip in the following SELOGIC 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
Courtesy of NationalSwitchgear.com
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