Date Code 20010625 Inputs, Outputs, Timers, and Other Control Logic 7-9
SEL-311L Instruction Manual
Figure 7.8: Configured Manual Close Switch Drives Local Bit LB4
Local bit LB4 is set to close the circuit breaker in the following SEL
OGIC control equation
setting:
CL = . . . + LB4 + . . .
SEL
OGIC control equation setting CL is for close conditions, other than automatic reclosing or
serial port CLOSE command (see Figure 6.1 in Section 6: Close and Reclose Logic).
Additional Local Control Switch Application Ideas
Local control switches can be applied to almost any control scheme that traditionally requires
front-panel switches. The preceding settings examples are OFF/MOMENTARY switches.
Local control switches configured as ON/OFF switches can be used for such applications as:
v
Reclosing relay enable/disable
v
Ground relay enable/disable
v
Remote control supervision
v
Sequence coordination enable/disable
Local Control Switch States Retained
Power Loss
The states of the local bits (Relay Word bits LB1 through LB16) are retained if power to the
relay is lost and then restored. If a local control switch is in the ON position (corresponding
local bit is asserted to logical 1) when power is lost, it comes back in the ON position
(corresponding local bit is still asserted to logical 1) when power is restored. If a local control
switch is in the OFF position (corresponding local bit is deasserted to logical 0) when power is
lost, it comes back in the OFF position (corresponding local bit is still deasserted to logical 0)
when power is restored. This feature makes the local bit feature behave the same as a traditional
installation with panel-mounted control switches. If power is lost to the panel, the front-panel
control switch positions remain unchanged.
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