GE AK-50 Series - Power Sensor Trip Maintenance

Low
Voltage
Power
Circuit
Breakers
GEK
-
7303
REVERSE
CURRENT
TRIPPING
DEVICE
AK
-
SO
ONLY
(
Fig
.
31
)
The
device
is
enclosed
in
a
molded
case
and
is
mounted
on
the
right
pole
base
similar
to
the
series
overcurrent
tripping
device
.
The
reverse
current
tripping
device
(
see
Fig
.
28
)
consists
of
a
series
coil
(
2
)
with
an
iron
core
mount
-
ed
between
two
pole
pieces
(
9
)
,
also
a
potential
coil
(
7
)
connected
across
a
constant
source
of
voltage
and
mounted
around
a
rotary
-
type
arm
-
ature
(
10
)
.
Calibration
spring
(
6
)
determines
the
armature
pick
-
up
when
a
reversal
of
current
occurs
.
REPLACEMENT
(
Fig
.
31
)
After
removing
the
wiring
for
the
potential
coil
the
reverse
current
device
can
be
removed
and
replaced
by
following
the
procedure
outlined
for
replacing
the
series
over
current
device
.
For
wiring
,
see
Fig
.
31
)
.
POWER
SENSOR
TRIP
GENERAL
DESCRIPTION
All
AK
-
3
Type
Air
Circuit
Breakers
contain
Power
Sensor
Overcurrent
Trip
Devices
.
Power
Sensor
Trip
functions
with
solid
state
components
with
the
exception
of
the
Solenoid
Trip
which
is
used
to
trip
the
breaker
on
signal
from
the
Power
Sensor
Unit
.
The
Power
Sensor
Overcurrent
Trip
Device
consists
of
four
major
components
.
The
As
long
as
the
flow
of
current
through
the
breaker
is
in
the
normal
direction
,
the
magnetic
flux
of
the
series
coil
and
the
magnetic
flux
of
the
potential
coil
produce
a
torque
which
tends
to
rotate
the
armature
counterclockwise
.
The
calib
-
ration
spring
also
tends
to
rotate
the
armature
in
the
same
direction
.
This
torque
causes
the
armature
to
rest
against
the
stop
screw
(
12
)
attached
to
a
bearing
plate
on
the
right
side
of
the
device
.
If
the
current
through
the
series
coil
(
2
)
is
reversed
,
the
armature
(
10
)
tends
to
move
in
the
clockwise
direction
against
the
restraint
of
the
calibration
spring
(
6
)
.
When
the
current
reversal
exceeds
the
calibration
setting
,
the
armature
revolves
clockwise
causing
the
trip
rod
(
3
)
to
move
upward
engaging
the
trip
paddle
(
1
)
,
there
-
by
tripping
the
breaker
.
ADJUSTMENTS
(
Fig
.
31
)
The
only
adjustment
to
be
made
on
the
reverse
current
device
is
to
make
sure
that
the
trip
rod
has
a
minimum
overtravel
of
1
/
32
in
.
beyond
the
point
of
tripping
the
breaker
.
This
adjustment
should
have
to
be
made
only
when
an
old
device
is
being
replaced
by
a
new
one
.
The
new
device
will
be
factory
adjusted
so
that
the
top
end
of
the
trip
rod
(
3
)
will
extend
1
/
2
in
.
above
the
top
of
the
device
case
,
and
no
addi
-
tional
adjustments
of
the
trip
rod
should
be
required
.
To
obtain
the
proper
1
/
32
in
.
over
-
travel
,
close
the
breaker
and
proceed
as
follows
:
1
.
Loosen
the
locking
nut
(
2
B
)
.
2
.
Manually
lift
the
trip
rod
and
vary
the
position
of
the
adjusting
nut
(
2
A
)
,
this
establish
-
ing
the
position
of
the
adjusting
nut
where
the
breaker
is
just
tripped
.
NOTE
:
Be
sure
to
keep
clear
of
moving
breaker
parts
when
tripping
the
breaker
.
3
.
With
this
position
of
the
adjusting
nut
established
,
advance
the
adjusting
nut
upward
one
and
one
-
half
turns
.
4
.
Tighten
the
locking
nut
and
the
minimum
1
/
32
-
in
.
overtravel
of
the
trip
rod
should
be
obtained
.
1
»
The
magnetic
coils
around
the
breaker
conductors
(
Fig
.
32
&
33
)
.
2
.
The
Power
Supply
which
provides
both
the
tripping
energy
and
the
comparison
basis
for
overcurrent
detection
(
Fig
.
34
)
.
3
.
The
Power
Sensor
Unit
with
the
various
pick
-
up
settings
and
time
delay
selection
taps
(
Fig
.
35
)
.
4
.
The
trip
solenoid
which
physically
trips
the
breaker
(
Fig
.
36
)
.
In
addition
to
the
phase
overcurrent
protection
,
a
ground
fault
sensing
feature
may
be
provided
.
The
Ground
Sensing
Device
works
on
the
principle
that
the
instantaneous
value
of
current
flowing
in
the
three
conductors
(
or
;
in
four
conductors
on
four
wire
systems
)
must
add
to
zero
unless
ground
current
is
flowing
.
Therefore
,
if
the
electrical
system
is
a
four
wire
wye
system
with
the
neutral
grounded
at
the
transformer
,
the
fourth
sensing
coil
Fig
.
38
must
be
included
on
the
neutral
conductor
with
its
secondary
combined
with
the
secondaries
of
the
three
phase
sensors
which
are
mounted
on
the
breaker
.
On
Draw
-
out
breakers
the
output
of
the
external
neutral
sensor
must
enter
the
breaker
by
a
control
disconnect
which
is
mounted
low
and
on
the
centerline
on
the
back
of
the
breaker
.
Refer
to
Fig
.
(
37
)
for
Power
Sensor
Cabling
Diagram
.
MAINTENANCE
When
mal
-
functioning
of
thePower
Sensor
Trip
is
indicated
,
the
trouble
should
be
traced
to
one
or
more
of
these
four
components
involved
,
and
that
component
should
be
replaced
as
a
unit
.
The
following
steps
should
be
taken
to
detect
a
mal
-
functioning
unit
.
No
adjustment
to
the
taps
controlling
NOTE
:
pick
-
up
should
be
made
with
the
breaker
car
-
rying
current
.
In
the
event
the
Power
Sensor
Device
must
be
made
non
-
operative
to
allow
the
breaker
to
33
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