Effective 11/2003
Page 21
I.L. 66A7535H02
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 twenty two available Short Delay Current
Settings, as illustrated in Figure 4.3.
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. The I
2
t response
provides an additional delay timer for currents less than
8 times the
I
r rating. For currents greater than 8 x (
I
r)
the
I
2
t
response reverts to the FLAT response.
IMPORTANT NOTE:
The Short Delay Time setting is the
fastest response time for the I
4
or IEEE or IEC response
curve. (See curves for more information.)
1. The above statement is applicable even if the Short
Pickup may not be “picked up.”
2. The above statement assumes a zone interlocking or
self-interlocking restrain signal is present.
3. The instantaneous of Ground (Earth) Fault may have a
faster response time.
Also see Section 3.3, Zone Interlocking.
4.2.1.7 INST PU Setting
There are at least 22 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.
Figure 4.4 Short Time Settings
Available Settings
1.5 to 12x with steps of 0.5
.
or *
1.5 to 14x with steps of 0.5
In Multiples of
Long
Setting ( r)
I
Short PU
Setting
* Additional M1 Value is Specified on Rating Plug
2 x r
I
Available SHORT TIME Settings
using
FLAT SHORT SLOPE
100A PLUG 0.1 to 0.5 in 0.05 steps
200A - 400A PLUGS 0.1 to 1.0 in 0.05 steps
600A - 2000A PLUGS 0.1 to 2.0 in 0.05 steps
Available SHORT TIME Settings
using
I2T SHORT SLOPE
100A PLUG 0.1 to 0.5 in 0.05 steps
200A thru 400A PLUGS 0.1 to 1.0 in 0.05 steps
600A thru 2000A PLUGS 0.1 to 2.0 in 0.05 steps
I2T SLOPE
RETURNS TO FLAT
RESPONSE AT CURRENTS
HIGHER THAN THAN 8x Ir
