4.177
Date Code 20170927 Instruction Manual SEL-751 Relay
Protection and Logic Functions
Global Settings (SET G Command)
TOL Pickup parameter makes it possible to set the individual light threshold levels
for each of the eight sensors. Pickup level is expressed in the percent of full
scale, which is directly related to the light intensity level measured by the sen-
sor.
When necessary, channel sensitivity can be compared to a light intensity level
expressed in lux as shown in Table 4.75. However, because light sensitivity is
associated with fiber length (which is installation dependent), TOL element settings
are expressed as a percentage of the available A/D converter range.
The default processing interval in the SEL-751 is one-fourth of the power
system cycle. However, to obtain a faster arc-flash protection you can select
two outputs that are processed every 1/16 of a power system cycle. Use the
setting AOUTSLOT to select these outputs. For instance, if Slot 3 is selected
(AOUTSLOT := 301_4) the SEL
OGIC control equations OUT301 through
OUT304 are processed at 1/16 of a cycle rate. To get the fastest possible oper-
ate time use the contacts selected by the AOUTSLOT setting for tripping.
Figure 4.103 shows the TOL element logic diagram.
Table 4.74 Arc-Flash Time-Overlight Settings
Setting Prompt Setting Range
Setting Name :=
Fac to ry Default
SENSOR 1 TYPE NONE, POINT, FIBER AFSENS1 := NONE
TOL 1 PICKUP 3.0–80.0 %
a
0.6–80.0 %
b
a
Setting range with point sensor.
b
Setting range with fiber sensor.
TOL1P := 3.0
SENSOR 2 TYPE NONE, POINT, FIBER AFSENS2 := NONE
TOL 2 PICKUP 3.0–80.0 %
a
0.6–80.0 %
b
TOL2P := 3.0
SENSOR 3 TYPE NONE, POINT, FIBER AFSENS3 := NONE
TOL 3 PICKUP 3.0–80.0 %
a
0.6–80.0 %
b
TOL3P := 3.0
SENSOR 4 TYPE NONE, POINT, FIBER AFSENS4 := NONE
TOL 4 PICKUP 3.0–80.0 %
a
0.6–80.0 %
b
TOL4P := 3.0
•
•
•
•
•
•
•
•
•
SENSOR 8 TYPE NONE, POINT, FIBER AFSENS8 := NONE
TOL 8 PICKUP 3.0–80.0 %
a
0.6–80.0 %
b
TOL8P := 3.0
AFD OUTPUT SLOT 101_3, 301_4, 401_4 AOUTSLOT := 101_3
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