11-10 Front-Panel Interface Date Code 20001006
SEL-351 Instruction Manual
The MANUAL CLOSE switch is an OFF/MOMENTARY type switch, like the MANUAL TRIP
switch, and operates similarly.
See Local Control Switches in Section 7: Inputs, Outputs, Timers, and Other Control Logic
for details on how local bit outputs LB3 and LB4 are set in SELOGIC Control Equation settings
to respectively trip and close a circuit breaker.
Local Control State Retained When Relay Deenergized
Local bit states are stored in nonvolatile memory, so when power to the relay is turned off, the
local bit states are retained.
For example, suppose the local control switch with local bit output LB1 is configured as an
ON/OFF type switch (see Figure 11.5). Additionally, suppose it is used to enable/disable
reclosing. If local bit LB1 is at logical 1, reclosing is enabled:
If power to the relay is turned off and then turned on again, local bit LB1 remains at logical 1,
and reclosing is still enabled. This is akin to a traditional panel, where enabling/disabling of re-
closing and other functions is accomplished by panel-mounted switches. If dc control voltage to
the panel is lost and then restored again, the switch positions are still in place. If the reclosing
switch is in the enable position (switch closed) before the power outage, it will be in the same
position after the outage when power is restored.
Note: In the factory default settings, the reclose enable/disable function is provided by
optoisolated input IN2 with the following SELOGIC Control Equation drive-to-lockout
setting:
79DTL = OC + !IN2 + LB3 [=NOT(IN2) + LB3]
Local bit LB3 is the output of the previously discussed local control switch configured as
a manual trip switch. The relay is driven to lockout for any manual trip via LB3.
When input IN2 is energized (IN2 = logical 1), reclosing is enabled (not driven-to-
lockout):
79DTL = ... + !IN2 + ... = !(logical 1) + ... = NOT(logical 1) + ... = logical 0 + ...
If local bit LB1 is substituted for input IN2 to provide the reclose enable/disable
function, the SELOGIC Control Equation drive-to-lockout setting is set as follows:
79DTL = OC + !LB1 + LB3 [=NOT(LB1) + LB3]
Courtesy of NationalSwitchgear.com
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