Effective 10/2004
Page 24
I.L. 70C1036H05
current returns to normal, the LTM begins to reset; after
about 10 minutes it will have reset fully, so the next Long
Delay trip time will again correspond to the Setting value.
NOTE:
In certain applications and field testing, it may be
desirable to disable the LTM function by disabling this
function in Program Settings.
The action of the LTM must be considered when performing
multiple Long Delay Time tests
(See Section 5.4).
4.2.1.5 SHORT PU Setting
There are at least nineteen available Short Delay Current
Settings, as illustrated in Figure 4.3. Eighteen settings are
in the range from 1.5 to 10 times (
I
r).
REMEMBER:
(
I
r)
is
the Long PU Current Setting.
The maximum value M1
depends on the sensor rating of the circuit breaker and is
listed in Note 3 of Table 1.1.
Figure 4.3 Short Delay Current Settings
4.2.1.6 SHORT TIME Setting
As illustrated in Figure 4.4, there are two different Short
Delay Slopes: fixed 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.
NOTE
: The I
2
t response for Short Time is not available if
LongTime is set for I
4
t, IEEE or IEC curve.
Nine FLAT and nine I
2
t response time delay settings are
available. The I
2
t response is applicable to currents less
than 8 times the ampere rating of the installed rating plug
(
I
r). For currents greater than 8 x (
I
r)
the
I
2
t response
reverts to the FLAT response.
NOTE:
Also see Section 3.4, Zone Interlocking.
Figure 4.4 Short Time Settings
4.2.1.7 INST PU Setting
There are at least 18 available Instantaneous Current
Settings, as illustrated in Figure 4.5. The value that M1
has depends upon the sensor rating of the circuit breaker
and is specified both on the rating plug label and on the
applicable time-current curves referenced in Section 9.2.
The Instantaneous Pickup is based on the plug (
I
n) rating.
4.2.1.8 GND PU Setting
The Ground Fault Current Settings are labeled with values
from .24 to 1.0x (
I
n) in 0.01 increments
(See Figure 4.6).
The ANSI/UL models are limited to 1200A, as shown in
Table 1.1. The IEC-EF model Earth Pickup range is 0.10
to 1.0x (
I
n) with no 1200A limitation. External control
power is required to insure earth fault tripping for fault
currents and earth fault setting less than .24 per unit.
Short PU
Setting
Additional M1 Value is Specified on Rating Plug
2 x r
I
( r)
I
Available Settings
.1, .15, .2, .25, .3, .35,
.4, .45, .5
Seconds with
FLAT SHORT SLOPE
I2t SLOPE
Returns to FLAT
Response at Currents
Higher than 8x r
I
8x r
I
Short Delay
Time
.4 Sec.
.1, .15, .2,.25, .3, .35,
.4, .45, .5
Seconds with
SHORT SLOPE
I t
2
