Eaton Cutler-Hammer Digitrip 1150 Instructions Manual page 22

Page 22
Figure 4.1 Long Delay Current Settings
4.2.1.3 LongTIME Setting
There are 45 available Long Delay Time Settings I
illustrated in Figure 4.2, ranging from 2 to 24 seconds. For
4
the I t slope theare are 9 settings ranging from 1 to 5
seconds. These settings are the total clearing times when
the current value equals 6 times ( I r).
Figure 4.2 Long Delay Time Settings
NOTE: In addition to the standard Long Delay Protection
Element, the Digitrip 1150 trip units also have a Long
Time Memory (LTM) function, which protects load circuits
from the effects of repeated overload conditions. If a
breaker is closed soon after a Long Delay Trip, and the
current again exceeds the Long Delay Setting, ( I r), the
LTM automatically reduces the time to trip to allow for the
fact that the load circuit temperature is already higher
than normal because of the prior overload condition. Each
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time the overload condition is repeated, the LTM causes
the breaker to trip in a progressively shorter time. When
the load current returns to normal, the LTM begins to
reset; after about 10 minutes it will have reset fully, so the
.4, .45, .5, .55, .6, .65
next Long Delay trip time will again correspond to the
.7, .75, .8, .85, .9, .95, 1.0
Setting value.
NOTE: In certain applications, 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 perform-
ing multiple Long Delay Time tests (see Section 5.4).
2
T, as
4.2.1.4 SHORT PU Setting
There are 19 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). ( REMEMBER: ( I r) is the Long
Delay Current Setting. ) The maximum value M1 depends
on the sensor rating of the circuit breaker and is listed in
Note 4 of Table 1.1.
2, 2.5, 3, 3.5 ,4, 4 .5,...
22 , 22.5, 23 , 23.5 , 24
Figure 4.4 Short Delay Current Settings
4.2.1.5 SHORT TIME Setting
As illustrated in Figure 4.5, there are two different Short
Delay Slopes: fixed time (FLAT) and I
selected depends on the type of selective coordination
chosen. The I
delay for current below 8 x I r than will the FLAT response
curve.
Nine FLAT and nine I
available. The I
than 8 times the ampere rating of the installed rating plug
( I r). For currents greater than 8 x ( I r) the I
reverts to the FLAT response.
NOTE: Also see Section 3.4, Zone Interlocking.
Short Delay
Setting
2 x r I
Additional M1 Value is Specified on Rating Plug
2 t response curve will provide a longer time
2 t response time delay settings are
2 t response is applicable to currents less
I.L. 70C1036H01
Available Settings
1.5, 2, 2.5, ...
9, 9.5, 10
In M ultiples
of Long Delay Setting
( r) I
2
t. The shape
2
t response
Effective 8/18/99