R.3.10
SEL-421 Relay Reference Manual Date Code 20111215
SELOGIC Control Equation Programming
Multiple Setting Groups
The operation of these settings is explained with the following example.
Assume the active setting group starts out as setting Group 3. Corresponding
Relay Word bit SG3 is asserted to logical 1 as an indication that setting
Group 3 is the active setting group.
With setting Group 3 as the active setting group, setting SS3 has priority. If
setting SS3 is asserted to logical 1, setting Group 3 remains the active setting
group, regardless of the activity of settings SS1, SS2, SS4, SS5, and SS6. With
settings SS1 through SS6 all deasserted to logical 0, setting Group 3 still
remains the active setting group.
With setting Group 3 as the active setting group, if setting SS3 is deasserted to
logical 0 and one of the other settings (e.g., setting SS5) asserts to logical 1,
the relay switches from setting Group 3 as the active setting group to another
setting group (e.g., setting Group 5) as the active setting group, after
qualifying time setting TGR (global settings):
In this example, TGR qualifies the assertion of setting SS5 before it can
change the active setting group. Relay Word bit CHSG asserts when the TGR
timer is picked-up and timing, and also when a setting group change has been
initiated.
Active Setting Group
Changes
The SEL-421 is disabled for less than 1 second while in the process of
changing active setting groups. Relay elements, timers, and logic are reset,
unless indicated otherwise in the specific logic description. For example, local
bit (LB01 through LB32), remote bit (RB01 through RB32), and latch bit
(PLT01 through PLT32) states are retained during an active setting group
change. The output contacts do not change state until the relay enables in the
new settings group and the SEL
OGIC control equations are processed to
determine the output contact status for the new group.
After a group change, an automatic message will be sent to any serial port that
has setting AUTO := Y. See Table 5.4
Active Setting:
Nonvolatile State
Power Loss
The active setting group is retained if power to the relay is lost and then
restored. If a particular setting group is active (e.g., setting Group 5) when
power is lost, the same setting group is active when power is restored.
Settings Change
If individual settings are changed for the active setting group or one of the
other setting groups, the active setting group is retained, much like in the
preceding explanation.
If individual settings are changed for a setting group other than the active
setting group, there is no interruption of the active setting group, so the relay
is not momentarily disabled.
TGR Group Change
Delay Setting
(settable from 0 to 54000 cycles)
NOTE: The CHSG Relay Word bit
does not operate for settings changes
initiated by the serial port or front
panel methods.
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