5.4
SEL-311C Relay Instruction Manual Date Code 20060320
Trip and Target Logic
Trip Logic
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 Front-
Panel Target LEDs on page 5.31.
Unlatch Trip
Once Relay Word bit TRIP is asserted to logical 1, it remains asserted at
logical 1 until all the following conditions come true:
➤ Minimum Trip Duration Timer stops timing (logic output of the
TDURD timer goes to logical 0)
➤ Output of OR-1 gate in Figure 5.1 deasserts to logical 0
➤ One of the following occurs:
➢ SELOGIC control equation setting ULTR asserts to
logical 1,
➢ The front-panel {TARGET RESET} pushbutton is pressed,
➢ Or the TAR R (Target Reset) command is executed via
the serial port.
The front-panel {TARGET RESET} pushbutton and the TAR R (Target Reset)
serial port command are primarily used during testing. Use these to force the
TRIP Relay Word bit to logical 0 if test conditions are such that setting ULTR
does not assert to logical 1 to automatically deassert the TRIP Relay Word bit.
Other Applications for the Target Reset Function
Note that the combination of the {TARGET RESET} pushbutton and the TAR R
(Target Reset) serial port command is also available as Relay Word bit
TRGTR. See Figure 5.17 and accompanying text for applications for Relay
Word bit TRGTR.
Factory Settings
Example (Using
Setting TR)
In this example the “communications-assisted” and “switch-onto-fault” trip
logic at the top of Figure 5.1 are not used. The SEL
OGIC control equation trip
setting TR is now the only input into OR-1 gate and flows into the “seal-in and
unlatch” logic for Relay Word bit TRIP.
The factory settings for the trip logic SEL
OGIC control equation settings are:
TR = M1P + Z1G + M2PT + Z2GT + 51GT + 51QT + OC (trip conditions)
ULTR = !(50L + 51G) (unlatch trip conditions)
The factory setting for the Minimum Trip Duration Timer setting is:
TDURD = 9.000 cycles
See the settings sheets in Section 9: Setting the Relay for setting ranges.
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