Date Code 20011205
Inputs, Outputs, Timers, and Other Control Logic
7-31
SEL-311B Instruction Manual
Settings Example
In the SEL
OGIC
control equation settings, a SEL
OGIC
control equation timer may be used for a
simple breaker failure scheme:
SV1
=
TRIP
The TRIP Relay Word bit is run through a timer for breaker failure timing. Timer pickup setting
SV1PU is set to the breaker failure time (SV1PU = 12 cycles). Timer dropout setting SV1DO is
set for a 2-cycle dropout (SV1DO = 2 cycles). The output of the timer (Relay Word bit SV1T)
operates output contact OUT103.
OUT103
=
V1T
Additional Settings Example 1
Another application idea is dedicated breaker failure protection (see Figure
SV6
= IN101
(breaker failure initiate)
SV7
= (SV7 + IN101) * (50P1 + 50G1)
OUT101
=
SV6T
(retrip)
OUT102 = SV7T
(breaker failure trip)
Figure
7.25: Dedicated Breaker Failure Scheme Created with SEL
OGIC
Control Equation
Variables/Timers
Note that the above SEL
OGIC
control equation setting SV7 creates a seal-in logic circuit (as
7.25) by virtue of SEL
OGIC
control equation setting SV7 being set equal to
Relay Word bit SV7 (SEL
OGIC
control equation variable SV7):
SV7
= (SV7 + IN101) * (50P1 + 50G1)
Optoisolated input IN101 functions as a breaker failure initiate input. Phase instantaneous
overcurrent element 50P1 and residual ground instantaneous overcurrent element 50G1 function
as fault detectors.
Summary of Contents for SEL-311B
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