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Effective 8/2006
Page 15
I.L. 66A7534H04
Connector
(Storage)
“LTM Active
”
Connector
(Bridging)
“LTM Inactive
”
Test
Kit
Test
Kit
(Also Recommended
Position for
Field Testing)
Digitrip Test Kit Port
Notch
Available Settings
1.5, 2, 3, 4, 6, 8, 10, M1
In Multiples of
Long Delay Setting ( r)
I
Short Delay
Setting
M1 Value is Specified on Rating Plug
2 x r
I
Figure 4.5 Short Delay Time Settings
Five FLAT (.1, .3, .4, .st1,st2 seconds) and three I
2
t (.1*,
.3*, .5* seconds) response time delay settings are avail-
able. The I
2
t response settings are identified by an asterisk
(*). The time settings labeled st1 and st2 are based on the
rating plug. For 100A st1 and st2 =0.5s. For 200A through
400A, st1 = 0.5s and st2 = 1s. For rating plugs 600A and
greater, st1 =1s and st2 = 2s.The I
2
t response is appli-
cable to currents less than 8 times the ampere value of
I
r
rating. For currents greater than 8 x (
I
r)
the
I
2
t response
reverts to the FLAT response.
NOTE:
Also see Section 3.3 - Zone Interlocking.
4.6 Instantaneous Current Setting
There are eight available
Instantaneous
current settings,
as illustrated in Figure 4.6. Six settings are in the range
from 2 to 10 x (
I
n) the rating plug value, and the other two
settings are M1 x (
I
n) and Off. The value that M1 has
depends upon the plug rating of the circuit breaker and is
specified both on the rating plug label and on the
applicable time-current curves referenced in Section 9.
Figure 4.3 Long Time Memory (LTM) Jumper
The action of the LTM must be considered when performing
multiple
Long Delay Time
tests
(See Section 5.4).
4.4 Short Delay Current Setting
There are eight available “Short Delay Current Settings,” as
illustrated in Figure 4.4. Seven settings are in the range
from 1.5 to 10 times (
I
r). However there exists an addi-
tional maximum setting M1 that is based on
(In)
.It is set
for 14x (
In)
for all rating plugs up to 1250A and 12X for
2000A, 2500A.
REMINDER:
(Ir) is the “Long Delay Current Setting.”
Figure 4.4 Short Delay Current Settings
4.5 Short Delay Time Setting
As illustrated in Figure 4.5, there are two different “Short
Delay” response curve shapes: fixed time (FLAT) and I
2
t.
The shape selected depends on the type of selective
coordination chosen. The I
2
t response curve will provide a
longer time delay for current below 8 x
I
r than will the FLAT
response curve.
. ,. ,. , ,
1 3 4 st1 st2
PLUG
st1
st2
100A
0.5
200-400A
0.5
0.5
1.0
1.0
2.0
600-2500A