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GEI-86134,
Power Circuit Breokers
ADJUST
GAP
TO
0.060"
t.
o.oeo'
WITH
BREAKER
CLOSED
PIVOT
STUD
STATIONARY
CONTACT
Fig.
7.
AKR-30
wipe
adjustment
-
uieoo
from
top
of
breaker
CONTACT
ADJUSTMENT
Types
AKR-SO,
sOH
qnd
AKRU-SO
Use
the follorving
procedure toper{orm wipe ad-
justment:
1.
Open
the
breaker,
remove
arc
quenchers.
2.
Arrange the breaker
forslow-closing,
as de-
scribed
on
page
15
of GEK-7310.
3.
Select
one
pole
of the
breakerand place
a
thin
sheet
or strip
of tough
insulating
material,
such
as
myl.ar, over the stationary arcing
and
intermediate
contacts. This
strip
should
be
about
two
inches
wide and must prevent
the arcing and intermediate
contacts
from making contact
when
the breaker is
closed.
4.
Using
the
ratcheting
maintenance
handle,
slow-close the breaker
with the insulation
held
in
place.
Examine
the
insulation
to
make sure
it
"over-hangs" below the intermediate
contacts
.
5. Atiach
a
continuity checker (bell-set or light)
between
the upper and
lower
stud.
6.
Facing the
breaker, turn
the
wipe adjustment
stud clockwise
until
the checker indicates that
the
main
contacts have
parted.
An
open-end wrench
fits
the hex section
on
the stud.
?.
Turn the stud counterclockwiseuntil the main
contacts
just touch.
8.
From this
point,
advance
the
stud counter-
clockwise 270
degrees. This
will
be
4-1/2 flats.
9.
Trip
the
breaker,
remove
the
insulating
strips.
10.
Repeatthe above
procedure on
the
other two
poles.
8
CONTACT
ADJUST|YIENT
lype
AKRT-50
The
contact structure
of this
2000A
breaker is
conceptually
identical
to the
1600A
AKR-50
except
that
it
employs eight stationary main contacts in-
stead
of
six.
Constructionally, however, the
upper
stud assembly, movable contact arms
and
pivot
block are
unique
to
the
AKRT-50.
See
Figs.
8
and
9.
The two
movable contact
arms are
pin-coupled
to a
metal driving
link
whose opposite end is
threaded and screws
directly
into the
insulating
link.
This
arrangement
omits
the
wrench-operated
wipe adjustment stud provided on
the
AKR-30
and
-50
frames.
Instead, wipe
is
adjusted by detaching
the
driving link from
the movable contact
arms
and
then
rotating
it with
respect
to
the insulating link.
On the AKRT-50 the
proper
amount
of
contact
wipe exists
if
,
on a closed
breaker,
aII of
the
sta-
tionary main contacts
have
moved away from their
stops. This
condition can be checked
visually
by
removing
the arc
quenchers, closing the breaker
and
verifying that all eightstationary main
contacts
are "lifted off" their stops.
Should
wipe adjustment
appear
necessary, proceed
as
follows:
1.
Open
the breaker.
2.
Arrange the breaker
for
slow-closing as de-
scribed
on
page
15
of GEK-7310.
3.
Selecting one
pole, dri-ft out the
coupling pin
and
detach
the
drivinE
link from
the
movable con-
tact arms.
4.
Screw
the
driving link completely into
the
in-
sulating link.
5.
Back
out the
driving tink two
and one-half
turns.
Exceed
this
by whatever amount
is
neces-
sary to properlypositionthe
linkwithin
the movable
contact
arms.
6. Install
the coupling pin
and
retainer rings.
?.
Using the maintenance handle,
slow-close
the
breaker
and
observe
that
all
eight stationary
main
contacts move away
from their stops. If
this
con-
dition
is
not achieved, open the breaker, againre-
move the coupling
pin
and
back
out the driving link
an additional
half turn.
8.
Reassemble,
reclose thebreaker
and
recheck
wipe.
9.
Repeat
the above
procedure on the other
two
poles.
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