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GEI-86134, Power Circvil Breokers
CONTACT REPIACEIVIENf
Types
AKR-30,
3OH
ond
AKRU-3O
The
stationary contacts (arcing
and
mains)of
the
AKR-30
breaker frames are replaced
in
identical
fashion
to
that
employed
for
the intermediate
and
main stationary contacts of the
AKR-50.
To do so,
however,
it is
necessary
to
first
remove the arc
runner by removing
its
three holding screws.
Replacement
of
the single
movable contact
arm
is
accomplished
in like
marurer employed
for
the
AKR-50 breakers,
i.e.,
remove
and
replace
the
coupling
pin, pivot pin,
etc.,
as described
below.
CONTACT REPTACEMENT Types
AKR-SO, 50H,
AKRU-50
ond
AKRT-SO
Referring
to
Fig.
17 of GEK-?310,
arcing
con-
tacts (L) are
released
by
removing
the arc
runner
(5)
andthe
arcingcontact pivot
(6).
When
reassem-
bling,
make
sure
that
the insulating spacers
on
the
ends
of
the arcing contact pin (7)
and
the insulating
',vashers (B)
under the
lower
arc
runner fastening
screws are replaced.
Intermediate (2) and main contacts (3)
are re-
moved
by
disconnecting
their
springs.
The
end
pieces
on
the springs
(9)
have
a small
hole
for in-
serting a spring
puller.
While holding
the
contact,
puII the spring
and
lift it
off
the
end
of
the contact.
Replace
the contact by
holding
it
in
position (inner
end
behind the contact stop)
while
extending
and
engaging
the spring
on the outer
end. A
suitable
puller
can be fashioned
by forming a
hook on
the
end
of a length
of.
1/76-tnch diameter steel
wire.
The
two movable contact
arms (4) are
removed
by
drifting
out
pin
(10) connecting them
to
the in-
sulated coupling
(11).
Right angle
tru-arc pliers
are
needed
to remove and replace the tru-arc
re-
tainer
on
the
end of
the
pin.
Next,
remove
the
fastening screws,
washers,
springs
and
pivot
pin from
the pivot
below.
When
replacing the arms
ensure
that
all
spacers, springs
and
washers
are returned totheir original position.
Tighten the two
bolts in the contact arm pivot.
AKRU-3O
ond
-50
FUSED
BREAKERS
Except
for
the open
fuse lockout device
and the
integrally-mounted fuses on the
upper studs,
the
AKRU-30 and
-50 breakers are identical to the un-
fused
AKR-30
and
-50 models. Overcurrent trip
devices
are the
same
for
both types.
Fuse Sizes
ond Mounting
Table
3 lists
the range
of
fuse sizes
available
for
thesebreakers. TheClass L fuses are
mounted
as
shown
in Fig. 10.
Other than the
800A
size,
which has a
single
mounting
hole per tang,
each
L
fuse tang
has two
holes
sized
for one-half inch bolts.
Class
J
fuses rated 300
thru
6004. have
one
mounting hole
per
targ.
The 300, 350
and
400A
sizes require copper adapter bars per
Fig.
11.
IABIE
3
GT
CIT
rusTS
TOR
ATRU
BREAI(ERS
NEMA
Fuse
Class
600v
60 Hz
Breaker
Type
AKRU.
-5dl5o--
Ampere
Rating
Cat.
No.
Melting
Tine-
current
Curves
J
300x
3
50*
400x
GFSB3OO
350
400
GES
8004
ii
450
500
6no
450
500
600
I
I
I
V
L
800
1000
1200
1600
2000
.
800
1000
1200
1600
2000
GES-8005
I
I
I
I
V
Special
L
2500
GFgF2SOOAK
r.838?832
10
xMounting adapter
required
-
see
Fig.
11
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