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Date Code 990215 Inputs, Outputs, Timers, and Other Control Logic 7-11
SEL-351P Manual Técnico
The outputs of the remote control switches in Figure SECTION 7: .9 are Relay Word bits RBn
(n = 1 through 8), called remote bits. Use these remote bits in SEL
OGIC
Control Equations.
Any given remote control switch can be put in one of the following three positions:
ON (logical 1)
OFF (logical 0)
MOMENTARY (logical 1 for one processing interval)
Remote Bit Application Ideas
With SEL
OGIC
Control Equations, the remote bits can be used in applications similar to those
that local bits are used in (see preceding local control switch discussion).
Remote bits can be used much as optoisolated inputs are used in operating latch control switches
(see discussion following Figure SECTION 7: .14). Pulse (momentarily operate) the remote bits
for this application.
Remote Bit States Not Retained When Power is Lost
The states of the remote bits (Relay Word bits RB1 through RB8) are not retained if power to the
relay is lost and then restored. The remote control switches always come back in the OFF
position (corresponding remote bit is deasserted to logical 0) when power is restored to the relay.
Remote Bit States Retained When Settings Changed or Active Setting Group Changed
The state of each remote bit (Relay Word bits RB1 through RB8) is retained if relay settings are
changed (for the active setting group or one of the other setting groups) or the active setting
group is changed. If a remote control switch is in the ON position (corresponding remote bit is
asserted to logical 1) before a setting change or an active setting group change, it comes back in
the ON position (corresponding remote bit is still asserted to logical 1) after the change. If a
remote control switch is in the OFF position (corresponding remote bit is deasserted to logical 0)
before a settings change or an active setting group change, it comes back in the OFF position
(corresponding remote bit is still deasserted to logical 0) after the change.
If settings are changed for a setting group other than the active setting group, there is no
interruption of the remote bits (the relay is not momentarily disabled).
L
ATCH
C
ONTROL
S
WITCHES
The latch control switch feature of this relay replaces latching relays. Traditional latching relays
maintain their output contact state – they are not dependent on dc voltage to maintain their output
contact state. For example, if a latching relay output contact is closed and then dc voltage is lost
to the panel, the latching relay output contact remains closed.
The state of a traditional latching relay output contact is changed by pulsing the latching relay
inputs (see Figure SECTION 7: .10). Pulse the set input to close (“set”) the latching relay
output contact. Pulse the reset input to open (“reset”) the latching relay output contact. Often