Effective 8/13/99
Page 20
I.L. 70C1037H02
Figure 4.5 Short Delay Time Settings
Five FLAT (.1, .2, .3, .4, .5 seconds) and three I
2
t (.1*, .3*,
.5* seconds) response time delay settings are available.
The I
2
t response settings are identified by an asterisk (*).
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.
4.6 Instantaneous Current Setting
There are 8 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) or Off. 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.
Figure 4.3 Long Time Memory (LTM) Jumper
The action of the LTM must be considered when perform-
ing multiple Long Delay Time tests (see Section 5.4).
4.4 Short Delay Current Setting
There are 8 available Short Delay Current Settings, as
illustrated in Figure 4.4. Seven settings are in the range
from 2 to 10 times (
I
r). (
REMEMBER:
(
I
r)
is the Long
Delay Current Setting.
) The maximum value M1 is based
on the ampere rating of the circuit breaker and is listed in
Note 4 of Table 1.1.
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.
Courtesy of NationalSwitchgear.com
To Next Page
Loading...
