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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