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lnstallation and
Adjustments lnstructions
)>
v
Short
Time
Pickup
Short Time Delay
The short time
pickup
sets the level of high current the
circuit
The short
time delay
sets
the tripping delay
of the
trip
unit
in
breaker
is
allowed
to carry for
a
short
period
of time.
This
responsetoacurrentinexcessof theshorttimepickupcurrent
pickup,
together with
the
short time delay, allows
downstream
level. The
setting
of
the short
time delay selects
one
of
f
ive
f
ixed
circuit
breakers time to clear short circuit
faults
without
trip-
delay bands. The
lower
value
of
the
selected
band
def
ines
the
ping the upstream circuit
breakers. When
the pickup
level
is
minimum delay for the initiation
of
the
circuit
breaker
tripping.
exceeded,
the
trip
unit initiates
the
short time
fault
protection
The upper value
of
the
band
def
ines
the maximum time
for
the
tripping
sequence.
The
short time
pickup
may
be set to
2, 3,
4,
clearing
of
the
tripping action including circuit
breaker
open-
5,6,7
,8, or
12
times the long time setting.
Changing
the
long
ing
and
arc
quenching
time. The lower value
of
the short time
timesettingchangestheshorttimepickupcurrentlevel.
delaybandmaybesetto,0S, .15,.22,.30,or,40seconds.
The short
time pickup
is
also implemented to accommodate
possible
variances
in
the
tripping sequence
pickup value due
to
electronic components tolerances. The functional
opera-
tion
is the same
as it
is for
the
long time setting
previously
presented. The
tolerance
is
plus
20%/minus
0%.
Current in Multiples
of
Long
Time
Setting
5
10
50
100
.15
second
delay band
I
.22
second
delay band
Example
-
Short
Time Delay Bands (Fixed Delay)
Current in Multiples
of
Long Time Setting
2
3
4 5 6 78910
100
50
o
!,
c
o
o
o_^
(,lu
.;
E
tr
5
tt-
LOnO
Ilme
r
delav
h:nrl
JIIUII
LII
pickup
aI
4
Ite
set
Drur
L
urre
pruKUp
will be
between
4
and
4.8 times the
long time setting.
Example
Short
Time Pickup
v
13

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