Schweitzer Engineering Laboratories SEL-700G Series, Инструкция по эксплуатации

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4.194
SEL-700G Relay Instruction Manual Date Code 20170814
Protection and Logic Functions
Logic Settings (SET L Command)
Latch Bits
Latch control switches (latch bits are the outputs of these switches) replace
traditional latching devices. Traditional latching devices maintain output
contact state. The SEL-700G latch control switch also retains state even when
power to the device is lost. If the latch control switch is set to a programmable
output contact and power to the device is lost, the state of the latch control
switch is stored in nonvolatile memory, but the device de-energizes the output
contact. When power to the device is restored, the programmable output
contact goes back to the state of the latch control switch after device
initialization. Traditional latching device output contact states are changed by
pulsing the latching device inputs (see Figure 4.133). 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 (for example,
SCADA, RTU).
Figure 4.133 Schematic Diagram of a Traditional Latching Device
Thirty-two latch control switches in the SEL-700G provide latching device
functionality. Figure 4.134 shows the logic diagram of a latch switch. The
output of the latch control switch is the Relay Word bit LTn (n = 01–32) called
a latch bit.
Figure 4.134 Logic Diagram of a Latch Switch
If the setting SETn asserts to logical 1, the latch bit LTn asserts to logical 1. If
the setting RSTn asserts to logical 1, the latch bit LTn deasserts to logical 0. If
both settings SETn and RSTn assert to logical 1, setting RSTn has priority and
latch bit LTn deasserts to logical 0. You can use these latch bits in SEL
OGIC
control equations to create custom logic for your application.
The SEL-700G includes 32 latches. Table 4.55 shows SET, RESET, and
latches LT01–LT06. The factory-default settings for these should address most
applications. Review the default settings and make any changes necessary to
suit your application. The remaining latches are not enabled (see Table 4.54),
but are available for any special needs.
Set
Input Reset
Input
Output
Contact
Traditional
Latching
Relay
(+)
(–)
LTn
SETn
RSTn
(Set)
(Reset)
(n = 01 through 32)
Relay
Word
Bits
SEL
OGIC
Setting