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Power Circuil Breokers,
GEI-86134
1.
Movable contact
arm
2.
Stationary
main contact
3.
Stationary
arcing contact
4.
Contact
spring
5. Arc runner
Fig.
5.
AKR/AKRU-S} contact structure
(arc
quencher
remoued)
The wipe adjustment influence
s
proper
arc
trans
-
fer during interruption
of
fault
currents
.
"
Transfer'
'
of the arc
is
its
forced sequential
movement
from
the
intermediate contacts
to
the arcing
contacts to
the
arc runner andfinallyto
the arcquencher where
it
is
dissipated
andextinguished.
Itis
recommended
that
contact wipe
be
checked
periodically during
normal maintenance inspections.
CAUTION: BEFORE DOING ANY
OF
THE
FOLLOWING CONTACT
ADJUSTMENT
AND
REPLACEMBNT WORK, MECHAN-
ICALLY
DISCONNECT
THE
CLOSING
SPI1/NG
FROM THE MECHANISM
CAM
SIIAFT.
THE BREAKER CAN
NOW
BE
,,SLOW-CLOSEDI' USING
THE
MAINTE-
NANCE HANDLE.
CONTACT
ADJUSITilENT
Types AKR-3O,
3OH
ond
AKRU-3O
The contact arrangement
of the
800
ampere
frame AKR
and AKRU-3O
breakers
dilfers
signi-
ficantly from that
of the AKR-50
frame
size.
Each
pole consists of
a
single movable
contact
arm
acting
against
five stationary contacts, arranged vertically
as shown
in Fig.
5.
Proceedingfrom top to bottom,
1.
Movable contact
arm
2.
Stationary
main contact
3.
Stationary
arcing contact
Fig.
6.
AKR-S1H contact
structure
the
first
two contacts
serve as the arcing
contacts
and
the bottom
three are the
mains.
There are
no
intermediate contacts.
The contact assembly
for the
AKR-30H breaker
employs
the
same
AKR/AKRU-30 configuration, but
adds
a
fourth stationarv
main
contact at the
bottom.
See
Fig.
6.
The
following wipe adjustment procedure
is
ap-
plicable to
all
AKR-30 types:
1.
Open
the
breaker,
remove
arc quenchers.
2. Arrange the
breaker
for
slow-closing as de-
scribed
on
page
15
of GEK-?310.
3.
Using
the
ratcheting
maintenance
handle,
slow-close
the
breaker.
4.
Se1ect
one
pole
and,
using
a
flat or wire feeler
gage, measure
the
gap
between
the top
contact
and
its pivot
stud
as
shown
in
Fig.
?.
As
necessary,
adjust the
gap
to 0.060
* 0.020 inch by
turning the
wipe adjustment stud.
5.
Repeat
this procedure
on
the other two poles.
6. Trip
the
breaker.
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