Schweitzer Engineering Laboratories SEL-387E - Remote Bit Application; Remote Bit States Not Retained When Power Is Lost; Remote Bit States Retained When Settings Changed or Active Setting Group Changed; Multiple Setting Groups

Date Code 20080110 Control Logic 4-3
SEL-387E Instruction Manual
The outputs of the remote control switches in Figure 4.1 are Relay Word bits RBn (n = 1 to 16),
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 via the serial
port commands shown. Begin with the CON n (Control Remote Bit n) command, then specify:
SRB n (Set Remote Bit n) ON (logical 1)
CRB n (Clear Remote Bit n) OFF (logical 0)
PRB n (Pulse Remote Bit n) MOMENTARY (logical 1 for one-eighth cycle)
Remote Bit Application
With SEL
OGIC control equations, the remote bits can be used in applications where you want
certain logic to be remotely enabled or disabled, depending on operating conditions of the
system. Also, remote bits can be used in operating Latch Bit control switches in the additional
SEL
OGIC control equation Sets 1 through 3. Pulse (momentarily operate) the remote bits for this
application. Latch Bits are discussed later in this section.
Remote Bit States Not Retained When Power Is Lost
The states of the remote bits (Relay Word bits RB1 through RB16) 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 RB16) 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 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).
M ULTIPLE S ETTING G ROUPS
The relay has six (6) independent setting groups. Each group contains Configuration Settings,
General Data, Differential Elements, Overcurrent Elements, Voltage Elements, Volts-per-Hertz
Elements, Frequency Elements, Miscellaneous Timers, SEL
OGIC control equation Sets 1
through 3, Trip Logic, Close Logic, Event Report Triggering, and Output Contact Logic. These
settings can be viewed or changed via the SHO n and SET n commands. The settings for
selecting which of the six groups is to be active is contained in the Global settings area
(SHO G/SET G commands).
Active Setting Group Indication
Only one setting group can be active at a time. Relay Word bits SG1 through SG6 indicate the
active setting group: