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GEI-86134, Power Circuil Breokers
BREAKER
MAINTENANCE
SAFETY PRECAUTIONS
BEFORE INSPECTING
OR
BEGINNING
ANY
XMINTENANCE WORK
ON
THE
BREAKER, I7:
MUST
BE DISCONNECTED
FROM
ALL
VOLTAGE SOURCES, BOTH
POWER
AND
CONTROL,
AND BE
IN
THE 'IOPEN"
POSITION,
MANUAT
HANDTE
ADJUST'NENT
On
manually
-
operate d
AKR
bre
ake
rs,
the closin
g
springs may
be
charged
ei.ther
by a
single
135
de-
gree clockwise handle
stroke or up to four multiple
strokes of lesser
swing.
The
following
adjustment
procedures
should
be performed using
the
single-
stroke
method. By so
doing,
proper multi-stroke
operation
is
assured.
Referring
to Fig.
13
of
GEK-?310,
the
manual
handle
adjustment
is
made
via
adjustable
link
(16).
The length of
this link
is
controlled by turning
a
double-ended
stud
in its center.
A hex section in
mid-stud can be
engaged
by an
open-end wrench.
When
looking
down
on the breaker,
turning
the
wrench
clockwise lengthens the
link.
The opposite
motion shortens
it.
The range of adjustment
is
300
degrees. In the
confined space available,
each
wrench stroke imparts
15
degrees
movement.
The
best setting
is
approximately mid-range.
Fig.
4.
AKR-SA-30
bt,eaher
Opening
spring
Rejection
bracket
If
the
link
is
too long, the handle stroke
cannot
extend
the
closing spring
enough
for it to
go
over
center.
In this event, use
the
maintenance handle
to
complete
the spring charging.
The
breaker
can
then
be
closed and
opened
preparatory to further
shortening
of the link.
If the link
is
too short,
one-stroke charging is
not
possible.
However, more than one stroke
will
charge
the springs.
CONTACT MAINTENANCE
Breakers
subjected
to
frequent interruption
of
high
currents may eventually require
replacement
of their contacts.
The
generalrule for determining
need
of replacenrent
is
the
loss ofone-haLf or more
of the mass
of the contacttip
material.
Roughening
or light pitting
of the contact
surface
does
not
indi-
cate
loss
of ability to carry or interrupt
current.
When
contacts
are
replaced, they must be ad-
justed
to
ensure
that
the
proper
a:nount
of force is
developed between
the movable and
stahonary con-
tacts when the breaker
is closed.
This
is
called
the "wipe" adjustment. "Wipe"
is
the
distance
throughwhich the
stationarycontacts
move when the
breaker
closes.
It is
measured between
the
point
of contact on a
stationary contact when the breaker
is
open,
and
the
position of the
same
point when the
breaker
is
closed.
The
actual wiping motion is
greater
because
the
contacts
over-travel.
"Wiping"
imparts a sliding or "scrubbing"
action
to the con-
tacts.
1.
2.
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