4.12
SEL-387-0, -5, -6 Relay
Instruction Manual
Date Code 20050919
Control Logic
SEL
OGIC
Control Equation Sets (1 Through 3) Variables
Variables/Timers
shows the logic for the variables and timers. A SEL
OGIC
control
equation defines the variable S
n
V
m
. When this equation is true, the Relay
Word bit S
n
V
m
is asserted. If S
n
V
m
remains true for the length of the
S
n
V
m
PU setting, in cycles, the timer output asserts the Relay Word bit
S
n
V
m
T (variable timed out). If S
n
V
m
deasserts, S
n
V
m
T will deassert
S
n
V
m
DO cycles later.
Figure 4.3
Timed Variables in SEL
OGIC
Control Equation Sets
There are 16 variables of this type spread through the three SEL
OGIC
control
equation sets.
Timers Reset When Power Is Lost, Settings Are Changed, or Active
Setting Group Is Changed
If power is lost to the relay, settings are changed (for the active setting group),
or the active setting group is changed, the SEL
OGIC
control equation
variables/timers are reset. Relay Word bits S
n
V
m
and S
n
V
m
T are reset to
logical 0 and corresponding timer settings S
n
V
m
PU and S
n
V
m
DO load up
again after power restoration, settings change, or active setting group switch.
Latch Control
Switches
The SEL
OGIC
control equation latch bit 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
). 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 the external contacts wired to the latching
relay inputs are from remote control equipment (e.g., SCADA, RTU, etc.).
SnVm
SnVmT
Settings
Cycles
SnVm
(SEL
OGIC
control equation)
SnVmPU
SnVmDO
n = SEL
OGIC
control equation set number
m = Variable number
Relay
Word
Bits
Summary of Contents for SEL-387-0
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