GE AK-50 Series - Selective Tripping

Low
Voltage
Power
Circuit
Breakers
GEK
-
7303
5
.
Work
coils
toward
end
of
stud
.
Starting
with
one
outside
pole
,
slip
coils
off
stud
and
onto
your
right
arm
or
properly
supported
cyl
-
inder
,
now
move
to
center
pole
and
out
side
pole
until
coils
are
removed
place
coils
with
resistor
board
on
clean
flat
surface
.
When
removing
coils
from
your
arm
be
careful
not
to
break
or
foul
interconnecting
coil
wires
.
Also
note
location
of
spacers
.
Spaces
may
vary
in
thickness
their
purpose
is
to
space
coils
out
for
a
firm
fit
.
3
.
On
drawout
breakers
wired
for
the
fourth
ground
sensor
coil
,
unsolder
external
sensor
coil
leads
at
terminal
board
on
female
disconnect
plug
.
On
stationary
breakers
unsolder
twisted
shielded
pair
from
Terminal
Board
(
Fig
.
40
)
.
4
.
Remove
the
four
bolts
connecting
each
coil
assembly
to
the
pole
unit
.
5
.
Remove
the
coil
assemblies
taking
care
not
to
damage
the
inter
-
connecting
coil
wires
.
6
.
No
further
breakdown
of
the
.
coil
assem
-
blies
should
be
made
.
Do
not
remove
the
coils
from
around
their
iron
core
.
SELECTIVE
TRIPPING
Selective
tripping
is
obtained
when
the
breakers
in
the
electrical
aistnoution
system
are
arranged
on
the
basis
of
a
progressive
series
of
time
and
current
pickup
.
This
will
allow
the
breaker
having
the
shorter
time
setting
and
the
lower
pickup
to
trip
before
the
breaker
having
the
longer
time
setting
and
the
higher
current
pickup
,
provided
the
fault
is
on
the
part
of
the
line
protected
by
the
breaker
having
the
lower
setting
.
Hence
,
if
a
fault
occurs
in
any
part
of
the
electrical
system
,
only
the
breaker
nearest
the
fault
-
will
trip
.
In
order
to
reduce
the
possibility
of
damaging
the
equipment
and
to
provide
maximum
safety
to
the
operator
,
the
overload
caused
by
a
fault
is
removed
in
a
minimum
amount
of
time
by
selec
-
tive
tripping
.
Overloads
producing
current
up
to
five
or
ten
times
the
breaker
rating
are
removed
in
a
matter
of
a
few
cycles
while
currents
in
excess
of
this
value
are
removed
instantaneously
.
7
.
Replace
coil
assemblies
in
reverse
order
.
Sensor
Coils
(
AK
-
3
-
75
/
100
)
Only
(
Fig
.
33
)
1
.
Disconnect
control
plug
between
Power
Supply
Unit
and
Sensor
Coils
.
2
.
If
present
,
disconnect
fourth
ground
sensor
coil
lead
as
described
in
Step
3
above
.
3
.
Disconnect
resistor
board
from
backframe
by
removing
two
nuts
from
studs
welded
to
back
frame
.
bolts
and
nuts
.
Remove
the
two
remaining
hex
head
Lift
board
from
the
two
studs
.
4
.
Remove
collar
at
end
of
primary
dis
-
connects
by
loosening
two
alien
head
bolts
and
sliding
off
collar
.
1000
1000
I
I
I
'
"
LONG
TIME
DELAY
PICK
-
UP
ADJUSTABLE
—
FROM
B
TO
1.6
TIMES
BREAKER
M
.
0
NG
-
TIME
DELAY
PICK
-
UP
ADJUSTABLE
FROM
,
8
TO
1.6
TIMES
BREAKER
RATING
RAjl
500
-
V
,
500
200
•
200
100
,
TIME
ADJUSTABLE
IN
FACTORY
-
30
,
15
,
OR
5
SECONDS
(
IA
_
_
IB
OR
1
C
RESPECTIVELY
)
AT
_
.
600
%
OF
LONG
TIME
DELAY
PICK
-
UR
,
100
A
50
50
V
s
\
20
\
20
.
MAXIMUM
BREAKER
CLEARING
-
TIME
>
10
N
N
.
10
in
v
LJ
5
N
o
z
MAXIMUM
BREAKER
CLEARING
TIME
5
Z
o
TIME
ADJUSTABLE
IN
FACTORY
-
30
,
15
,
OR
5
SECOND
(
IA
,
IB
,
OR
1
C
RE
-
SPECTIVELY
)
AT
600
%
OF
LONG
TIME
DELAY
PICK
-
UP
O
S
O
/
SHORT
-
TIME
DELAY
PICK
-
UP
|
ADJUSTABLE
FROM
2
TO
lOi
TIMES
BREAKER
RATI
O
Ld
2
Ld
in
r
if
)
2
Z
.
MINIMUM
-
RESET
-
TIME
.
f
z
H
Ld
MINIMUM
RESET
TIME
Ld
h
-
INSTANTANEOUS
PICK
-
UP
SET
IN
FACTORY
-
4
TO
15
TIMES
.
21
-
BREAKER
RATING
N
N
1
TIME
ADJUSTABLE
IN
FACTORY
-
0.399
,
0266
OR
0.133
SECONDS
l
2
A
.
2
E
'
OR
2
C
RESPECTIVELY
)
AT
250
%
OF
SHORT
TIME
DELAY
PICK
-
UP
I
I
.
1
MAXIMUM
BREAKER
/
OPERATING
-
TIME
:
05
.
05
-
1
.
02
.
02
.
01
5
I
2
3
4
56
8
10
20
50
100
200
.
01
2
3 4 5 6 8
»
2 0
CURRENT
IN
TIMES
BREAKER
RATING
5 0
1 0 0
2 0 0
.
5
CURRENT
IN
TIMES
BREAKER
RATING
Fig
.
41
(
215
D
180
)
Typical
time
-
current
characteristics
for
Magnet
Overcurrent
Trip
Devices
39
Courtesy of NationalSwitchgear.com