Basic Breaker Components; Lubrication; Separation Of Front And Rear Frames; Replacement - Ak Breakers/Akf Breakers - GE AK-2-50 Maintenance Manual

At all . times it is important not to ·permit
pencil lines, paint, oil or .other foreign mater-
ials to remain on the insulating surf aces of the
breaker as they may cause low resistance between
points of different potential and result in eventual
electrical ~reakdown.
The breaker should-be operated several times
at a rated voltage to assure that the control
circuits are 'properly connected and that all
electrical attachments are functioning properly.
A complete contact inspection, including con-
tact wipe and · pressure, should be made at regu-
lar inspection periods and always after a known
short circuit current
has
been interrupted, to
determine whether the contacts are worn or
pitted in which case they should be dressed
or replaced.
It
is necessary to remove the arc
quenchers to properly inspect the contacts. Arc-
ing contacts and arc quencher barriers should be
replaced when they are eroded to half their
original thickness.
LUBRICATION
In general, the circuit breaker requires mod-
erate lubrication. . _ Mechanical bearing points
and sliding surfaces should be lubricated at the
regular inspe_ ction periods with a thin film of
G-E Lubricant D50Hl~ . Sli<lingsilver plated con-
tact surfaces should be lubricated with G-E Lub-
ricant D50H47. Hardened grease and dirt should
be removed from latch and bearing surf aces by
using kerosene. ALL EXCESS LUBRICANT SHOULD
BE REMOVED TO
AVOID ANY
ACCUMULATION
OF DIRT OR DUST. ·
The use of cotton waste to wipe bearing surfaces
should be avoided, as the cotton ravelings may
become entangled under the bearing surfaces and
destroy the surfac.e of the bearing.
On drawout breakers, the contact surface of the
disconnect studs should -be greased· with G-E
Grease Specificati~n D50H47. .
SEPARATION OF FRONT
AND REAR FRAMES
To repair or replace contacts· , operating mech-
anism, ox: the overcurrent devices, the front
frame must be separated from the back frame.
To -separate the two frames pro~eed as follows :
1. · _ The breaker contacts must be open with
the safe!}7 pin in place. (See MAINTENANCE.)
_ 2. Remove ·the two opening springs (on lower
part o! the ~reaker) from the outside pole units.
3. Remove the clevis pin (14, Fig. 6) (13, Fig. 7)
from the center pole unit.
4. Remove the six nuts from the back frame
using a socket wrench with an extension. These
include the two nuts at the top of the frame.
Low Voltage Power Circuit Breakers GEK-7303
5. Remove the auxiliary switch operating rod
·· (5-, Fig. 20).
6. Check along the· trip shaft for a mech-
anical interference or connection between the
overcurrent trip device and the trip paddles.
Remove mechanical · connection if present, or
if interference exists, use extreme care when
removing or re-assembling front and back frames
to avoid mechanical breakage of trip devices. In
reassembling the front and rear frames, the two
frames should be positioned vertically so that
the trip shaft is horizontally aligned.
NOTE: It is recommended that the breaker
be fastened to a suitable maouting base with
the front frame supported by a sling or hook
as the bolts are being installed.
BASIC BREAKER COMPONENTS
ARC QUENCHERS
(Fig •.. 4 and ·5)
The arc quenchers should be inspected at the
regular inspection period. If the barriers· are
cracked or eroded to one-half their original
thickness, they should be rep_lacec;i.
REPLACEMENT-AK BREAKERS
1. Be sure the breaker is open.
2. Remove the channel-shaped retaining bar
by removing two screws and two nuts.
3. Lift the quenchers clear of the · movable
arcing co~tacts.
4. .During _ replacement be careful r.iot to
overtight~n the screw which secure the channel-
shaped retaining bar. Overtightening the screws
will bow the bar and leave the center arc quen-
· cher loose. · · ·
REPLACEMENT- ·AKF BREA~ERS
The center-pole arc quencher of these breakers
is similar to · the arc quenchers of the standard
breakers and is replaced in a similar manner, ·
except that the breaker must be closed. With
the breaker closed the center-pole contacts are
open and the arc quencher can be remov. e d.
Replace the outer-pole arc quenchers of the
Type AKF breaker as follows:
1. Be sure the breaker
is
open.
2. Remove the two channel-shaped r_ etaining .-
bars which bear against the front of the arc
quenchers by removing four -screws, two on each
side. -
3. Lift .the arc quenchers clear
of
the movable
arcing contacts.
4. Replace arc quenchers and insert the four
screws holding the retaining bars in position.