Date Code 20060320 Instruction Manual SEL-311C Relay
Section 5
Trip and Target Logic
Trip Logic
The trip logic in Figure 5.1 provides flexible tripping with SELOGIC
®
control
equation settings:
TRCOMM Communications-Assisted Trip Conditions.
Setting TRCOMM is supervised by communications-
assisted trip logic. See Communications-Assisted Trip
Logic-General Overview on page 5.10 for more
information on communications-assisted tripping.
DTT Direct Transfer Trip Conditions.
Note in Figure 5.1 that setting DTT is unsupervised. Any
element that asserts in setting DTT will cause Relay Word
bit TRIP to assert to logical 1.
Although setting TR is also unsupervised, setting DTT is
provided separately from setting TR for target LED
purposes. (COMM target LED on the front panel illuminates
when DTT asserts to logical 1; see COMM Target LED on
page 5.32).
Typical settings for DTT are:
DTT = IN106 or DTT = RMB1A
where input IN106 is connected to the output of direct
transfer trip communications equipment or receive
M
IRRORED BIT
®
RMB1A is asserted by the transfer trip
condition in a remote SEL relay.
Setting DTT is also used for Direct Underreaching
Transfer Trip (DUTT) schemes.
TRSOTF Switch-Onto-Fault Trip Conditions.
Setting TRSOTF is supervised by the switch-onto-fault
condition SOTFE. See Switch-Onto-Fault Trip Logic on
page 5.7 for more information on switch-onto-fault logic.
TR Other Trip Conditions.
Setting TR is the SEL
OGIC control equation trip setting
most often used if tripping does not involve
communications-assisted (settings TRCOMM and DTT)
or switch-onto-fault (setting TRSOTF) trip logic.
Note in Figure 5.1 that setting TR is unsupervised. Any
element that asserts in setting TR will cause Relay Word
bit TRIP to assert to logical 1.
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