Micro Versa
Plus™ and
PM™
Units
2.
Mode
' .�
.,
·-� L.f
ST
SETUP
xiT
Figure
14.
Trip Unit display for short-time pickup coupled with
long-time pickup.
The time-current curve for short-time pickup is
shown in Figure
15.
Q)
E
i=
Current
Short-Time
Pickup Settings
Figure
15.
Time-current curve illustrating short-time pickup.
Short-Time Delay
The Trip Unit display for short-time delay is shown
in Figure
16.
This function delays the breaker trip on
a short-time trip. The choices of time-delay bands are
listed in Table
1 2 .
The delay with
I2T IN
is for a cur
rent of
600%
of
xLT
at the lower limit of the band.
The delay with
I2 T OUT
is for the lower limit of each
band.
On ANSI Trip Units ordered with the user
selectable, switchable instantaneous overcurrent and
ground-fault option, "X," an additional value of
OFF
appears at the end of the delay band settings. Choos
ing
O F F
disables short-time protection. The short
time
O F F
band is interlocked with instantaneous
pickup, so that only one function can be turned off
at a time.
The
I2T OUT
function, illustrated in Figure
17,
estab
lishes a constant time delay.
I2T IN
biases the delay
with a constant slope,
as
shown in Figure 18.
17
ST
'
'
SETUP
DELAY
Figure
16.
Trip Unit display for short-time delay.
Time Delays, sec
I
0.10
2
0.21
3
0
.3
5
Table
12.
Lower-limit delays for
t2rour
short-time delay bands.
Current
Delays with
Figure
11.
Time-current curve for short-time delay with
t2r OUT.
E
i=
Current
Figure
18.
Time-current curve for short-time delay with
htN.
www
. ElectricalPartManuals
. com
