4.4
SEL-2414 Transformer Monitor Instruction Manual Date Code 20130214
Logic Functions
General Logic Functions
General Logic Functions
SELOGIC Enables
Table 4.5 shows the enable settings for latch bits (ELAT), SELOGIC control equa-
tions (variables/timers) (ESV), counters (ESC), and math variables (EMV). This
helps limit the number of settings that you need to make. For example, if you
need six timers, only enable six timers.
NOTE: SV in the Setting Range
column of the settings tables indicates
a SEL
OGIC
®
control equation.
Latches
Operation
Latch control switches (latch bits are the outputs of these switches) replace tradi-
tional latching devices. Traditional latching devices maintain output contact state.
The SEL-2414 latches also retain state even when power to the device is lost. If
the latch is set to a programmable output contact and power to the device is lost,
the state of the latch is stored in nonvolatile memory, but the device de-energizes
the output contact. When power to the device is restored, the programmable out-
put contact will go back to the state of the latch after device initialization. Tradi-
tional latching device output contact states are changed by pulsing the latching
device inputs (see Figure 4.4). Pulse the set input to close (set) the latching
device output contact. Pulse the reset input to open (reset) the latching device
output contact. The external contacts wired to the latching device inputs are often
from remote control equipment (e.g., SCADA, RTU).
Thirty-two latch control switches in the SEL-2414 provide latching device func-
tionality. Figure 4.5 shows the logic diagram of a latch switch. The output of the
latch is a Device Word bit LTn (n = 01–32) called a latch bit.
Table 4.5 Enable Settings
Setting Prompt Setting Range Default Setting
SELOGIC Latches N, 1–32 ELAT := N
SEL
OGIC Variables/Timers N, 1–64 ESV := N
SEL
OGIC Counters N, 1–32 ESC := N
SEL
OGIC Math Variable Equations N, 1–32 EMV := N
Figure 4.4 Schematic Diagram of a Traditional Latching Device
Set
Input
Reset
Input
Output
Contact
Traditional
Latching
Relay
(+)
(–)
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