Table of Contents
Advertisement
GEK-731O,
Power Circuil Breokers
I
.
Arcing
Contact
2.
Interrnediate
Contact
3.
Main
Contacts
Contact
Arrn
Arc
Runner
Arcing
Contact Pivot
Fig.
17.
(1s4C2174)
The two bolts in the contact afm pivot are to
be
screwed
in until they bottom.
CONTACT
ADJUST'IAENT
When
contacts
are
replaced, they must be ad-
justed
to be sure
that
the proper
amount
of force
between the movable and stationary contacts
de-
velops when the
breaker
is closed.
The adjustment
that
does
this
is
called
the "wipe"
adjustment.
"Wipe"
is
the distance through which the
stationary
contacts move when the
breaker
closes. It is
mea-
sured
as the
distance 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. Actually, the wiping
motion
is
greater
since the contacts
over-travel.
"Wiping" imparts
a
sliding
or
"scrubbing"
action
to the contacts in
motion.
The wipe adjustment on AKR-50 breakers also
makes
correct the transfer action
of
the
arc
which
results from interrupting fault
current.
"Transfer"
of
the
arc is
its
forced sequential
movement
from
20
7. Arcing
Contact Pin
8.
Insulating
W'asher
9.
Contact Spring
Contact assembly
Coupling Pin
Insulating
Coupling
Adjustrnent
Stud
the intermediate contacts,
to
the arcing
contapts,
to
the
arc runner,
and
finally to
the arc
quencher
where
it
is
dissipated and extinguished.
The steps
to follow
in making
the
wipe adjust-
ment on
AI(R-50 breakers follow:
1.
Thebreakermustbe open andthe arcquench-
ers removed.
2.
Place a
thin sheet
or strip
of tough
insulating
material;
suchas
mylar, over
the
stationary arcing
and intermediate contacts. This
strip
should
be
about
two-inches rvide and must be placed
so
that
when
the breaker is closed,
the
arcing and inter-
mediate contacts
do
not make contact.
3.
Close the breaker with the insulation held in
place. Examine the
insulation
to
make
sure it
"over-hangs" below the intermediate contacts.
4. Attach a continuity
checking means
between
the upper
and
lower
stud.
Use
abell-set or
a
light,
not an
ohmmeter.
The
Iatter
does
not give
as
pre-
cise
an
indication.
I0.
11.
rz.
4.
6.
Advertisement
Table of Contents
