5-10
Trip and Target Logic
Date Code 20010625
SEL-311L Instruction Manual
Unlatch Trip With 52b Circuit Breaker Auxiliary Contact
A 52b circuit breaker auxiliary contact is wired to optoisolated input IN101.
52A = !IN101
(SEL
OGIC
control equation circuit breaker status setting—see
Optoisolated Inputs
in
Section 7: Inputs, Outputs, Timers, and
Other Control Logic
)
ULTR = !52A
Input IN101 must be energized (52b circuit breaker auxiliary contact has to be closed) before the
trip logic unlatches and the TRIP Relay Word bit deasserts to logical 0.
Program an Output Contact for Tripping
In the factory settings, the resultant of the trip logic in Figure 5.4 is routed to output contacts
OUT101 and OUT102 with the following SEL
OGIC
control equation settings:
OUT101 = TRIP
OUT102 = TRIP
The user can also route the trip logic to the high-current interrupting contacts OUT201 through
OUT206.
If more than two TRIP output contacts are needed, program other output contacts with the TRIP
Relay Word bit. Examples of uses for additional TRIP output contacts:
v
Keying an external breaker failure relay
v
Keying communication equipment in a Direct Transfer Trip scheme
See
Output Contacts
in
Section 7: Inputs, Outputs, Timers, and Other Control Logic
for more
information on programming output contacts.
S
WITCH
-O
NTO
-F
AULT
(SOTF) T
RIP
L
OGIC
Switch-Onto-Fault (SOTF) trip logic provides a programmable time window for selected
elements to trip right after the circuit breaker closes. “Switch-onto-fault” implies that a circuit
breaker is closed into an existing fault condition, such as when safety grounds are accidentally
left attached to a line. If the circuit breaker is closed into such a condition, the resulting fault
needs to be cleared right away and reclosing blocked. An instantaneous element is usually set to
trip in the three-pole open (3PO) logic and the SOTF trip logic.
Refer to the switch-onto-fault trip logic in Figure 5.4 (middle of figure). The SOTF trip logic
permits tripping if both the following occur:
v
An element asserts in SEL
OGIC
control equation trip setting TRSOTF
v
Relay Word bit SOTFE is asserted to logical 1
Relay Word bit SOTFE (the output of the SOTF logic) provides the effective time window for an
element in trip setting TRSOTF (e.g., TRSOTF = 50P2) to trip after the circuit breaker closes.
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