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Date Code 20010625
Trip and Target Logic
5-7
SEL-311L Instruction Manual
Set Trip
Refer to Figure 5.4. All trip conditions:
v
Communications-Assisted Trip, including Direct Transfer Trip
v
Switch-Onto-Fault Trip
v
Other High-Speed 87L Trips
are combined into OR-1 gate. The output of OR-1 gate asserts Relay Word bit TRIP to logical 1,
regardless of other trip logic conditions. It also is routed into the Minimum Trip Duration Timer
(setting TDURD).
The Minimum Trip Duration Timer (with setting TDURD) outputs a logical 1 for a time duration
of “TDURD” cycles any time it sees a rising edge on its input (logical 0 to logical 1 transition),
if it is not already timing (timer is reset). The TDURD timer ensures that the TRIP Relay Word
bit remains asserted at logical 1 for a minimum of “TDURD” cycles. If the output of OR-1 gate
is logical 1 beyond the TDURD time, Relay Word bit TRIP remains asserted at logical 1 for as
long as the output of OR-1 gate remains at logical 1, regardless of other trip logic conditions.
The Minimum Trip Duration Timer can be set no less than 4 cycles.
The OPEN command is included in the trip logic in the factory settings:
TR = … + OC
Relay Word bit OC asserts for execution of the OPEN Command. See
OPE Command (Open
Breaker)
in
Section 10: Line Current Differential Communications and Serial Port
Communications and Commands
for more information on the OPEN Command. More
discussion follows later on the factory settings for setting TR.
If a user wants to supervise the OPEN command with optoisolated input IN105, the following
setting is made:
TR = … + OC * IN105
With this setting, the OPEN command can provide a trip only if optoisolated input IN105 is
asserted. This is just one OPEN command supervision example—many variations are possible.
To prevent the execution of the OPEN command from initiating reclosing, include Relay Word
bit OC in the SEL
OGIC
control equation setting 79DTL (Drive-to-Lockout).
A COMM target LED option for the OPEN command is discussed in the
Front-Panel Target
LEDs
subsection at the end of this section.
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