GE AK-2-50 User manual

.)
MAINTENANCE MANUAL
LOW-VOLTAGE
.. -POWER CIR . CUil BREAKERS
.
· AK-2/3/2A/3A-50/50S
AK-2/3 /2A/3A-7 5 /7 5S
AK.:2/3/2A/3A.;.1QO/100S
TYPES
AKT-2/3/50/SOS _
AKU-2/3/2A/3A-50/ SOS
AKF-2C/2D/2E
GENERAL f/j ELECTRIC
' GEK -7303B ·
Supersedes
GEH -l 798A GEI - 50211
GEH-1799 GEI-50212A
GEH - 1823A GEI-67077
GEI - 50210A GEI-74600
:.

CONTENTS
INTR ODU CTION•••••••••••• •• ••••••• •• • •• • •• :••••••••••••••••• •••• ••••••••••••••• ~ •••••••••••••••••• ••
OPERATION•••••• •• •••••••••••••••••••••••·•••••••••••••• ~ •••••••• •• ••••• •• ~ • •• ••••••••••••••••••• •• •• ••
MA. NU AL CLO SING••••••••• ••• •• •••• •• ••••••••••••••••-•••••••••••••••••••••••••••••••-•••• •• • •• •
· MANUAL MA.INTENANCE CLOSING
OF ELECTRICAL BRE A KERS •• •••••••••••
ELECTRICAL CLOSING••:••• •• ••• •• ••• ••••••••••••••••• •• •• ~ •••••••••••• •• ••• •• •• •• ••••••••••
~tJICIC CLOSE
FOR ELECTRICAL BREAKERS •••••• •• •••••••••••• •• ••••••••••••••••••
E LECTRI C AL TRIPPING ••• •• •••• •• • •• •• •••••••· •• ••••••••••••••••••••••••••••••••;• •• ••••••••
MAINTENA NCE••• ~ ••••••••••••• •• • •••• •••••••••••••••••••••• ~ •••••• •• ••••• •• ••••••••••••••••• •• ••••••
INSERTING SAFETY PIN-AIC-50, AIC- 75 AND A K-100 •••• •• •••••••••••• •• ••••.••••••
IN
SPE C TION • •• •••••••••••••• •• • ••• •••••••• •• • ••• •••••••••• •• • •• • •• •••••••••••••••••••••••••••;••
TROUBLE SHOOTING~•••••••••••••••••• •• •••• •••• ••••••••••••••••••••••••••••••••••••••••••••
LUBRICATION••••••••••••
•• •••••• ••• • •• •• • •• •••• ••• ••••• •• ~ •••••••••••••••••••••••• •• ••••••• .- •••
S
EPARATION OF FRO NT AND REAR FRAM ES •• •;••• •• ••••••••••••• •• •••••••••••••••
.. · BASIC BREAKER COMPO NEN TS •• • •••• • ••• •••••••• •• •• •••••••• ••••• •• •:••••••-•••••••••••••;• •• •
ARC QUE NC HERS. :•••••••••••••• ~ •• ••••••·. .. . ............... . .... . ....... .. .. ...... .... ... . .... .
POLE UNIT AS SEMBLY •• •• •• • ••• •• •••••;• •••• •• •• ••••••• •••• :•••••••••••• •• •••••••••••••••••
.
OPERATING MECHANIS MS ••••••• ~ ••• •• • •••••• • •••• .••••:••••••••••••••••••• •• ••••••••••••••••
QUICIC
CLO SE BREAKE R ADJUSTMENTS•••• ~ ••••••••••••••••••••••••••••••••• •• •• •• ;.
AUXILIA.RY SWITCH •• ••~· •• •;•• •••• ••••••••••••••••••••••• •••• •••• •••• ••• •• ••••••••••••• •• •••••
ELECTRICAL -CLOSING DEVICES AND CONTROL S •••• ••• •• ••••••••• •••• ••• •• • ~ •••••••• ••
·CLOSIN'G SWITCH•••••••••••••••••••• •••• •••••• •• ••••••••••••••• ~ ••••••••••••••• •• • •• ••••••••••
CUT-OFF SWITCHES •• • •••• ••: • •• •••••• •• ••••••••• •• •••••••••••••••••••••••••••••••, •••••• •• ••
CON TROL RELAY ••• ~ ••:• •• • •••• :•••••••••:•••••••• •• •••••••••••••• •• ••••••••••••••••••••••••••
PROTE C TIVE DEViCES •• •••••••••• ••• ••••••••••••••••••••••.•••••••••••••• •• •••••••••;•••••• •• ••••
STATIC TIME DELAY UNDERVOLTAGE TRIIPIN G DEVI CE ••••••• •• ••••• •• • •••• •
INS TANTANE dus · uNDER VOLTAGE TRIPP ING DEVICE •• ••••••••••••••••••• •• • ••
lJND~R \T C>l,1'J\CiE LOCICC>l.J'I' I>~\TICE •• •••••••••••••• •• ••••••• •••• •••• •••• •••••••••••• •• •
DffiECT-ACT ING TRIPP ING DE V ICE-E C -lB •• •• ·••••••••••••••••••• •• •••••••••••••• •• •
S
ERIES OVER CURRENT TRIPP ING. DEVI CE Ec :.. 1. •••••• •• ••• •• ••••••••••••••••••••
SERIES
OVERC U RRENT TRIPP ING DEVICE E C- 2/ EC-2 A•••• ~ •• ••••• •• •••••••••••
REVERSE CURRENT:
TRIPP ING DEVICE (AIC-50 ON LY) • •• •· •• ••••••••••••••••••••••
POWER SE N SOR TRIP •• ••••••••••••••• ••• • •• •••• •• ••••••••••e••••••••• •• •••••••••• ••••••••••••
S ELECTIVE TRIPPING ••••••••• •• • •• •••••• ••• • •• • •• ••••••••••••••••••••••••••••••••••• •• ••••••
BREAKER ACCESSORIES•••••••••••••• ••• • ••• •••••••••••o•••••••••••••••••••••••••••••••••••••• •••
PRIMA.RY D1SCONN'EC1'S•••••••• ••• • •• ••• •• •••••••• •••••• ••••• •• • •• ••••••••••• •••• ••••••• •• •
SECONDARY DISCONN'ECT S •• •••• •• ••• •••• ••• •• ••••••••• ••• ••• ••••••• ••• •• •• ••• • •• •• ••••• ••
DRAWOUT MECHANISMS•• ••• ••• •• ••••• ••• • ~ •••••• •• •• •• •••••••••••••••••• •• ••••••••• •• •••••
~ SHUNT TRIPPING DEVICE ••••••••• ••• • •• ••• ••••••• •• ••••• •• • •• •••••••• •••••• ••••• •• • •• •••••
~ELL AI.,AR~ AND LOCl{()tJT I)E:\TIC E: •• • ••• •• •.• .•• • ••••• •••• ••• •••• •••• • ••• •• • •• •••••
OPE N FUSE LOCKOUT DEVICE•••••• •• •••••••••••••••••••••••••••• •• ••••• •• •••••••••• •• ••
~CE~~()lJS ••••••••••••••••• •••• •; •• ••• •• ~ •• •• •••••••• •• •••••••••••••••••••••••• •••• ••••••• ••••
1'()()1'8••••••••••••••••••••••••••••••••••••••••••••••••• .•• •.• .• .. ••. •••••••••••••••••••••••••••••••
RENEWAL PART S•••••••••••••••••••••• •• •• •••••••••• •• ••••••••••••• •• ••••••• •••• •• •• •••••••• ••
3
3
3
4
4 -
4
5
5
5·
5
6
7
7
7
7
8
13
16
11
23
23
25
25
26
29
31
33
33
39
42
42
42
43
44
44
45
47
47
47
Th . ue i ns lrvctiom do ·not purpori to cover all details or variations in ~ipment nor lo pro'!id• lor every possible -
contingency to be met in connection. with installation, operation or maintenance . Should further inlormoli on be desired
or should particul ar problems arise which are not cove r_ ed sufficiently lor t~e purchaser 's purposes, the matter should
be referred to t he General Electric Company . · ·

LOW-VOLTAGE POWER CIRCU~T BREAKERS -·
TYPES .AK•SO,
AK-100 ;
AKF-2C, AKF- 2D, AKF-2E
OPERATION
INTRODUCTION .
The instructions contained herein are intendedto
aid in the maintenance and repair of basic breakers
and accessories for AK-50-75 -1 00 Low Voltage
Power Circuit Breakers. ·
The basic AK_.50, AK-75 and ·AK-100 breaker
designs have been expanded to include special
designs for specific applications. These design
extensions have caused variations in the nomen-
clature including the following:
AK-2-50, AK-2-75
or AK-2-100 - Basic
standard design of breaker for stationary
mounting or for drawout use in AKD type
equipment.
AK-2A-50, AK-2A-75, ·AK-2A-100 -The
A
indicates it .has_mounting. features for
AKD-5 type equipment.
AK-2-50S, AK-2-75S, AK-2-lOOS -
The S
indicates breaker is equipped with a quick-
close mechanism · which provides closing
times of approximately5 cycles (.08 seconds) ..
..
AKU-2-50- - The u. indicates an internal
fuse breaker combination:
AKF-2C, AKF-2D, AKF-2E . -Are fie ld
switches for use in .controlling shunffields
of synchronous m~tQ~s and generators.
. AK -2-50H - .The H Indicates the inter-
. rupting rating has - been increased to the
75,000
amp . class. . · , _ ·
-
AK -2- 50C,- AK~2 -7 5C- :.. The C indicates
the interrupting rating has been increased
to the rno,ooo amp. class . .
AKT-2-50 -
The · T indicates incr~ased. · ·
continuous
rating of 2000 amps.
AK-3-50, AK - 3-75, AK-3-100 -The 3
indicates the breaker ls equippe!i with the
Power Sensor OVercurrent Trip Device.
AK-2-
50X - - The x· indicates the - breaker
has very special features or it "includes_·
two
or more . of the design extensions
previously described. - .-
When contacting .
the factory' it is important
to furnish the complete nameplate · information.
MANUAL CLOSING
For a description of manual closing, refer
to the section of these instructions entitled CLOS -
ING THE BREAKER - MANUALLY OPERATED
AK-50 and
section entitled AK-50-75" AND-100
STORED ENERGY
MANUAL MECHANISM, both
under OPERATING MECHANISMS.
-'"'
o<:>
a:<(
1-1-
%-'
oo
u>
4'
G
G
,fl
LE GEND
® • CLOSING MOTOR
~ • RELAY COIL
,1, • RELAY CONTACT
CLOSING 1
SWITCH 1
-- : :-~J
REMOTE
CLOSE
.x .
F&G • MECHANICALLY OPfRATED SWITQIES .
·+• NOR MALLY OPEN SWITCH CONTACTS
I • NORMALLY CLOSED SWITCH COffTAC_!S
L • AUXILIAAY SWITCH CONTACT
SIMPLIFIED ELEMENTARY DIAGRAM
INTERNAL WIRING AK_:50, 75, AND 100 ·
Fig;l.
lOSING -1 l'l£ MOTE "
.r
r
SWITCH I T' l OSE
I • I
G h; E
G
" l
LEGEND
~C : ~'fc,~l'i,\ ii t~~ fo~lTACTS
( - ANTI-PUMP A£lAT C<J,ITACTS
r tG: ~~/r,:ti~~~~Wc\O.,l~lt>f:S
j : ~~~~1s?ct•r C Oi l
~ =~'l::.W& i~'i.1.~ ~TACT:,
<j, - t.ORMAllT OptN SWITCH CONTACTS
'f' - NORMAU.T ClOS(O SWITCH CONTACTS
INT(~l~.lf 1 ~GC~fi~nt~~~U:icR
Fig. lA.
w
-,--
I
:~ TR IP
I
I
'
[. ..
OIL .
1
0

GE;K-730~ Low Voltage Power Circuit Breakers
MANUAL MAINTENANCE
- . ~ CLOSING OF ELECTRICAL
BREAKE~S
· An electrical breaker may be closed manually
by _means of the maintenance handle furnished
'with the
breaker. ·
·
To observe ~e operation of the breaker with- ·
out power, with the break~r open and springs
discharged, proceed as follows:
1. · Charge the·closing spring with tbe main~
te~ance
han~e (1, Fig. 3) until the indica-
tor rea~ "charged": .
2. Continue to
operate the.maintenance handle
until the
breaker close~.
3. Open. ·the breaker by . pushing· the trip .
· _·button(4, "
F~1t. 2)~ . . .
ELlCl'.RICAL CLOSIN~
The - electrical control s·ystem · is comprised
of-an- X relay, two double_contact mechanically
operated switches (F anq G), a push outton closing
switch and _any means for remote closing which
the user may incorporate into the system. When
voltage
is . .first .applied to the breaker, (before any
closing s'ignal
is given) the motor is energized
through two of the X relay contacts and the two
a ·. switch contacts.· The-.motor then compresses
the closing springs to the "pre-charged" position
at which point the mechanically operated F and G
·
switc~es are ope_ rated. This ope_ ns the G contacts,
stop~mg the motor, and closestheF contacts,whicp
readies the system for the. actual closing of the
breaker .. When the push button ~r remote switch ·
signals · for a closing operation, the X relay coil is
e~ergized, operating the X contacts. This seals
· in the X relay and energizes the.motor once again
and
tl?,e closing operation takes place. . .
QUt:CK CLOS.E
FOR ELECTRICAL BREAKERS
. Functionally, the ·quick close mechanismdiffers
from the standard electrical mecbanism in that the
pre-charge operation is extended ·to completely
charge the closing springs. At theendofthe charg-
ing oper~tion, w~ch takesapproximately5seconds,
a
latch plate engages the prop roller to prevent
_theclosing springs from discharging. .
. With
the closing springs fully charged the
breaker is ready for a closing operation upon
release of the prop roller. This may be accom-
plished
either m~ually, by depressi .ng the closing
.
lever on. the breaker, or electrically by closing
the
remote closing switch. Upon the release of
. the prop
roller the closing springs discharge and
close the breaker in the same manner as on the
·
stan~ard electrical breaker.
· Wi~ . control voltage appli~d, :the motor is ·.·
energized through the .G switch. contacts, ·and
charges the closing springs. When the springs
4
reach the fully charged position; the mechanically
operated switches operate, reversing their coniact:S.
Upon
operation of these switches the motor. 1s
stopped by the.opening of theGswit~h. The closing
of the F
switch prepares the bre . aker for- a
closing
operation.
Fig. 2 (8939671)- Front view of AK-2-50 bre~e~
. 1. Auxiliary Switch· .
2. Position Indicator
3. Relay
4. Manual
Trip Button
5. Shaft
for Manual Mainte- ·
nance Closing Handle · ·
6. Spring Charged-Discharged
Indicator · ·
7. Motor Cut-off·Switches
8.
Arc Quenchers
A closing
signal now given· energizes the cont;;
relay X whose contacts close and comple: the
circuit through the closing relay coil. . Wi 8
closing relay coil energized the breaker clo~eg
.
as descr~bed above. At the same time the· clos:P
l\elay contact closes to energize the anti-pU
rel~y .causing
its c· ontacts to re\_'erse providing
the.anti-pump feature. ·
When the
breaker closes, themechanical oper~~
ted G switc hes close to energize the motor ag~-
. and the F switches open and de-ene:1;gize the :er- ·
trol relay from being .energized until the brtsed
is tripped open. With' the .G switc~es c dy'
the motor charges the closing sprlngs rea
for the next closing operation.

EL ECTR IC AL TRIPPING
-
The breaker may be tripped electrically by any
of tha
electrical tripping devices described in
these instructions. . The breaker may also be
tripped by the automatic overcurrent or reverse
current tripping devices, if so equipped. All
these devices trip the breaker inasimilarmanner,
i.e. ·the device trip arm moves against the trip
paddles fastened on the trip shaft , thus rotating
the
trip shaft and displacing the trip latch.
The
most commonly used tripping device is the
shunt trip device connected in the control circuit
as shown in Fig. 1. Whena tripping signal is given,
the shunt
trip coil is energizedthrougha nortrlally-
open auxiliary switch "
a" -contact, thus tripping
· tbe
breaker.
. .
MAINTENANCE
BEFORE INSPECTION OR ANY MAINTENANCE
WORK IS DONE BE SURE THAT THE BREAKER
IS IN THE OPEN POSITION. ALL ELECTRICAL
POWER, BOTH PRIMARY
AND · CONTROL
SOURCES, SHOULD
ALSO BE DISCONNECTED.
Warning: On
breakers employing stored-en-
ergy closing mechanisms, care must be taken
when the
circuit breaker is being installed
and when any inspection or maintenance work
is being done so that the breaker is in the
open·
position and the closing springs are
·being re15trained by the safety pin. The proce-
dure for inserting the safety pin is given below.
-INSERTING SAFE TY PIN -
AK -5 0, - 75 and -100 ·
. (Fig •. 3) . .
The closing sprini ~hould be charged with the
maintenance handle
(1) so that the safety pin (3) -
can be
placed in the hole of the push rod (2).
Continue to op
er . ate the maintenance·handle, clos-
ing the breaker. This is done so that the safety
pin
takes the SJ?ring force .
- To il)stall the
safety pin of the manµal stored -
energy mechanism
refer to the section entitled
STORED-ENERGY MANUAL MECHANISM on page
17 of these instrucUons.
With the safety pin
restraining the closing
spring force, the. contacts will close s.lowly when ·
the
breaker is manually operated a1lowing the
operation of the mechanism and the contact align-
ment ~o be visually observed.
. . -
. !allowing the inspection period, the closing
sprmgs must be recharged, the safety pin removed
from the push rod, and the pinplaced in the retain-
ing spring clip adjacent to the push rod.
Low Voltage Power Circ~it Breakers GEK-7303
Fig. 3 {8039670) View showing operation of
· AK-2-50·
breaker with manual maintenance
handle and installation.of safety pin,
1.. Manual maintenance'Handle
2.
Push Rod
3. Safety Pin
INSPECTI ON
Periodic inspection of the circuit break~r is
recommended · at least once a year. · More fre-
quent inspections are recommended if severe
load. conditions, dust, moisture or _ other unfavor
able conditions
exist. A complete inspection
.of the
breaker, includingcontactsand arc quenchers,
should always
be made after the breaker has in-
terrupted a short-circuit.
At regular inspection periodsthe breaker should -
be
operated manually; (stored energy mechanisms ·
with the
safety pin restraining the closing spring
force)
fo observe the contact alignment and to
make
sure all mechanism parts move freely
without binding
or excessive friction.
If the breaker remains -open or closed for a·
period of six months or more, it is recommended
that arrangements . be made to open and close it
several times in succession, .preferably under.
load.
If overheating, not caused by overcurrent, is
observed, a complete inspection of the breaker
should be made including connections and contacts.
5

GEK-7303 Low Voltage Power Circuit Breakers
6
TROUBLE
Overheating
Failure to Trip
AK-2 Breakers
Failure to Trip
AK-3 Breakers
False Tripping
AK-2 Breakers
False Tripping
AK-3
Breakers
Failure . to Close
and Latch
Burned Main
Contacts
TROUBLE SHOOTING
CAUSE
Contacts not aligned.
Contacts
dirty, greasy or coated
with dark film;
Contacts badly burned or pitted.
Current-carrying surfaces
dirty.
Corrosive atmosphere.
Insufficient bus
or cable capacity.
Bolts and nuts at terminal connections
uot tight.
Current in excess
of breaker rating.
Excessive ambient temperature.
Inductive heating;
Travel
of tripping device does not provide
positive releasegt tripping latch.
Worn
or damaged trip unit parts.
-Binds in overcurrent trip de.vice._
Loose
or Disconnected Power Sensor
Disconnect Plugs.
Loose
or Broken Power Sensor Coil
Tap Connections. -
Overcurrent pick
up too low. _
Overcurrent time setti!)g too
short.
Bind in overcurrent trip device.
Captive Thumb Screw
on Power Sensor
Loose Fail-Safe Circuitry Reverts .
Characteristic to Minimum Setting
and Maximum Time Delay.
Tap Setting Dial on Power Supply
Incorrectly Set.
External Ground Sensor Coil
Improperly Connected.
Binding in attachments preventing
resetting of latch.
Latch out
of adjustment.
Latch
return spring too weak or broken.
Hardened
or gummy lubricant.
Safety pin left in push rod.,
Motor burned out.
Faulty control circuit component.
Improper contact sequence (main contacts
not sufficienUy parted
when arcing contacts
part). .
Short.circuit current leJel above inter-
rupting r.ating of breaker.
Loss
of contact wipe or pressure.
· REMEDY
Adjust contacts.
Clean contacts.
Rep~ace contacts.
Clean
surfaces of current-
carrying parta.
Relocate or proVide adequate
enclosure.
Increase capacity of bus or cable.
Tighten, but do not exceed,
elastic
limit of bolts or fittings.
Check
breaker application or modify
circuit by _decreasing load. _
ProVide adequate venWation. -
C~rrect bus or ·cable arrangement.
Re-adjust
or _replace tripping device.
Replace
trip unit.
Replace overcurrent trip device.
Tighten
or Reconnect Disconnect.
Plugs.
Tighten or Reconnect Tap Connections. __
Check application of overeurrent
trip deVice. ·
Check appllcatiOn
of overcurrent
trip deVice.
Replace
overcurrent trip device.
Tighten Thumb Screw on
Desired
Setting.
Set Dial to Correspond with Power
Sensor Coi! Tap.
Refer to
Fig. 40 Page 38 for Pola_rity
and Connections. Check Continuity
of Shield and Conductors Connecting
the
External Ground Sensor Coil
Re-align and adjust attachments.
Adjust latch,
~eplace spring.
Clean bearing and latch surfaces,
Remove safety pin,
Replace motor. ,. -
Replace or adjuat faulty device.
Increase arcing contact wipe. Adjuat
contact sequence by raising or lower-
ing main movable contact pivot block.
ReQuires system study and possible
replacement With breaker haVing ade-
quate interrupting capacity.
Replace stationary contact
springs
and dress .up or replace contacts. _

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 towipe 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, o x: 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 theclevispin(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 hori zontally 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
arcin g co~tacts.
4. .During _replacement be careful r.iot to
overtight~n the
screw which secure thechannel-
shaped retaining
bar. Overtighteningthe 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.ed.
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.

GEK-7303 Low Voltage Power Circuit Breakers
1·· 2
. . . .. .
. ..
.. .. :
:;.: : ·: :··: ~-- .
..
,, , ' .·. : ··...
...
..: .- : :
Fig. 4 (8014830) Disassembly of arc quenchers-standard breaker and AKF center pole .
1. Stud
2. Cap
3. Side Barrier
4. Pocket Barrie~
5. Inner Barrier
DISASSEMBL Y~AK AND AKF
CENTER POLE (Fig. 4) -
The following instructions apply to both tl1e
Type AK and AKF breaker center poles.
1. Remove arc quenchers (see REPLACE-
MENT).
2. Remove screws holding spacer block (9).
3. Remove
spacer block, steel back plate
(8), and compound support (7).
4. Rock muffler (6) slightly and remove.
The inner barriers (5) can now be removed for
inspection.
5. Remove nut and withdraw
stud (1).
6. Remove cap (2). The
side (3) and pocket
(4) barriers should be free.
7. Reassemble and replace the arc quencher
in the reverse order. Tighten the fastenings
after replacement.
DISASSEMBLY- AKF OUTER
POLES (Fig. 5)
1. Remove arc quenchers (8Ce abov e) and lay
on sides on a flat surface. ··
2. Remove hardware
from one side of arc
quencher as indicated in Fig. 5.
6. Muffler
7. Compound
Support
8. Steel Back Plate
9. Spacer Block
3. Remove bolt fastening cap (4) and barrier
plate assembly.
4. Barrier plates may now be lifted from as-
sembly for inspection.
5. In reassembling, make sure · components
are positioned so that holes for self-tapping hard-
ware are in line. Do not strip threads in compound
by
overstressing screws.
POLE UNIT A SSEMB LY (Fig. 6)
NOTE: The text and part identification numbers
contained in this section apply to illustrations
covering the AK-50 breaker. The same text
is · applicable to the AK - 75 and 100 breakers by
referring to Fig. 7 and identifying the similar
parts. These similar parts may not, in every
case, be identified by the same number .
Each pole unit assembly consists of a set of
arcing contacts, a set of mai~ contacts, the
actuating linkage and the mounting
base. See
Fig. 8 and 9, pole unit assemblies mounted on
back
frame assemblies.
The stationary arcing-contact assembly con- ,
sists of a set of parallel contact fingers (2),
pin (3), and compression sprin gs (22), which
provide continuous contact pres s ure for the fu ll

GEK-7303 Low Voltage Power Circuit . Breakers
Fig. 5 (8019408) Disassembled arc quencher- AKF outer poles.
1. Muffler Assembly
2.
Spacer Block
3. Inner Barrier
4. Cap
travel ·of ·the contacts. Steel springs (5) shunt
the pivot pin to
pr _event possible pitting at the
pivot point when interrupting high
currents. · On
earlier model breakers flexible braid leads were
used.
rhe movable ~rcing-contact a~sembly consists
of
parallel contact arms (4) carried on two mov-
·able pivot
pins (8) and (19). The arcing con.tacts
interleave the main·contacts and pivot with them
about pin (19).
This relative motion is obtained by.
linkages
from the upper pin (7) to the breaker
mechanism. . . ·
Th·e
stationary main contact assembly includes
main and
intermediate contacts. The intermediate-
contact surface extends beyond the main contacts
and will,
therefore, make before the main contacts
and
break after the main contacts. The number
of contacts
for each breaker rating is · given
in
Table I.
The movable main contacts pivof around a
stationary pin (18), which holds them .to the
lower ·block. Motion is obtained from a second
pin .(7), connected by an insulated link (12).to tl\e
breaker mechanism. In addition to ste · e1 springs
shunting the current from the contact · directly to
!the
lower contact block, steer springs (17) force
liiie
con~cts ag~nst the pins to prevent pitting
at the pivot pomt. The movable main contact
jassembly
also contains main and intermediate
!contacts.
5. Intermediate
Barrier
6. Outer Barrier
.7. Side Plate
In order to function properly, a definite amount
of contact
pressure and contact wipe must exist
between . the movable and stationary contacts.
Table I gives the
figures for contact pressure and
contact wipe. Both wipe and
pressure should be
cpecked during the_
regular inspection period. -:
MEASURING CONTACT WIPE (fig. 6)
· 1. Remove arc quenchers (see REPLACEMENT
under
ARC QUENCHER). .
2. With the
breaker open, measure the hori-
zontal distance
from . the edge of the stationary
contact to the
stationary block behind it. ('.'B"
dim.
for arcing contacts, "C" dim. for .main
contacts). ·
3. Clo.
se the breaker and repeat item 2. The
difference between the readings in items 2 and 3
determines the wipe of the ·contacts. For safety
reasons be extremely careful not to trip the
breaker. · . ·
MEASURING CONTACT PRESSURE
(Fig. 6)
1. Remove arc quenchers(seeREPLACEMENT
UNDER ARC QUENCHER).
2. Close the
breaker and measure dimension
"B".
3. Open the breaker. Place a push-type scale

Low Voltage Power Circuit Breakers GEK-7303
TABLE
Main Contacts -Intermediate Contacts Arcing Contacts
No. or
Pres- Wipe No. of Pres- Wipe No. of
Pre=r- Wipe
Breaker ontacts
sure In In Contacts
sure In ln Contacts
sure In Ill
Type
Per Pole Lba,
Inches
Per Pole Lbs, Inches
Per Pole Lb s,
lnches
-
AK-SO tor AC 3 55 to 65
4/64 to 1 55 to
65
. 2 31 to 43 12/64 to
. '1/64 18/64
-
AK-SO tor DC
3 55 to 65
1/16 to
'1/64 . 1 55 to
65 ' • 3 31
to 43 12/64 to
18/64
AK-75
tor AC
5 35 to 45 1/16 to
7/64 1 35 to 45 . 3 31
to 43 12/64 to
18/64
-"
35 to 45
1/16 to
12/64 to
-
AK-75 tor DC
5 I 35
to 45
• 5
31 to 43
?/64 18/64
-. -
AK-I 00 for AC
8 25 to 35 1/16 to 2
25 to 35 •
5·
31 to 43 12/64
to
AK -100 tor DC
?/64 18/64
_ AKF-2C 3 55 to
65
1/16 to .
1,
55 to 65
• 2 31
to 43 12/64
to -(Oulside Poles .•. '1/.
64 . 187?4.
.
AKF-2D (Outside 5 55 to 65:. 1/16 io I
55 to 65
• · 3
31 to 43
12/64 to
AKF-2£' (Poles)
·:
'1/64 . . 18/64
-
AKF•2C (Field
AKF-2D Discbarge 0
------- -----
Contacta) 0
-----··--
-- 2
..
10 io 16 28/64 to
40/64
..
-
• The intermediate conta~t wipe should be at le~t 1/16 in. greater than main·contact wipe.
~ • Ldt stationary contact ext;nda approximately 3/32 in. ~ 1/32 further than right band contact.
against the stationary arcing contacts at.a point
measured
in line with the breakbetweenthecontact
stop and the contact pivot block. Push the contact
backward until dimension ."B" ·recorded in item
2
is reached. The scale should then be read.
4. If the pressure is not within the require-
ments listed on TABLE I, refer to the section
of these instructions dealing with
ADJUSTING
CONTACT WIPE AND PRESSURE.
ADJUSTiNG ·coNTACT . WIPE
AND PRESSURE (Fig. 6)
1. To obtain proper contact wipe andpressure
on the
center pole, dimension "A" should be
increased to increase wipe and decreased to
decrease wipe.
· 2. To ch.ange dimension "A" removethe clevis
pin
(14) and rotate the clevis as necessary.
. 3. .To prevent overstressing theclevisthreads
(13) dimension." A" should not exceed 3/16 in. and
space.
'.'A" should be filled with shims to 0.005 in.
of being solid.
·
4. With the proper center pole WiJ>e obtained,:.
moving·
the crossbar adjusting plate {lOA) on the
center pole to the right will simultaneously
in-
cre a se the wipe on both outside. poles; moving
the adjusting plate to the left will have the
reverse
effect.
5. To increase ·the wipe on either outside pole
individually, move the
crossbar adjustin~ plate of
that pole to the left; to decrease the wipe move
the adjusting
plate to the right.
NOTE: If the proper contact pressure
does not exist when the contact y.,ipe is
within its limits, the stationary contacts
springs should be replaced. ·.
CONTACT SEQUENCE (Fig. 6)
On the horizontal plane, the difference in the
making of the arcingcontacts
on the samepole must
be
no greater than 1/32 in.; the difference ~e~
tween arcing contacts on separate poles 1/16 m.
If it is desired to advance or retard the closing
of the main contacts of a pole .loosen the bolts
holding the adjustment plate
(10A) of that pole
and
slide plate to the left to advance con~ct
closing, or to the right to retard contact ~los~g
Make this adjustment on the outer poles, usmg
the
center pole as a reference. Upon retight-
ening adjustment plate· bolts,
make. sure the lock-
ing tabs are turned up a:r:ound bolt heads, locking
the bolts securely in p~ace. . . .
. Contact sequence·
in the vertical plane should
be such·
that when the. arcing contacts are just
touching,
the intermediate contact gap should be

1. Screw .
2. Stationary Arcing Contact -
3. Pin (Stationary Arcing Contact)
4. Movable Arcing Contact
5.
Spring (Leaf Contact) _
5A. Stationary Intermediate Contact
6. Movable Main Contact ·
. 7. Shouldered Pin
1
2
3
4
Low Voltage Power Circuit Breake~s GEK-7303
- 28 ·
~
--------- 27
26
8. Pin (Arcing Contact Links) 5
~---t-..,,._---.....::,aa-...,
•--r--+---+----...-- 22
.J.------~l -
9. Insulating Link ·
.
10. Pin (Insulating Link)
lOA. Adjusting
Plate
5A-~--t---\----~-
______ 20A
10B. Buffer Spacers
11. Pin (Side Link)
12. Link
13. Clevis
14. Clevis Pin
6
'l
8
9
___ 20
~~f/r:J__..-------1~
----18
15. Lower Stud
16.
Pole Unit Base
10 -----
1-----16
· 17. Spring (Main Movable Contact)
18.
Pin (Main Movable Contact) ·
lOA ____ ,
19. Pin (Movable Arcing Contact)
20. Side
Link - _
20A.
Contact Stop . - · -
21.
Spring -(Statio:f1ar.y Main Contact) - -
22•.
Spring (Stationary Arcing Contact)
23.
Upper Stud -_ ·
24. Leaf Spring (Stationary Main Contacts)
· 25. Pin (Stationary Main Contact) -
26. Stationary Main Contact
27• .
screw .
28. Stop
=- .:=.;,,.-i----,
{ -.
I
I
15
. Fig. 6 (0107D7517rPote unit assembly-AK-50 _
a:t least 3/16
1/4 in.
in., the ·main: contacts gap at l~ast - spacers on the cross-bar • . The ~ocking nuts <?D
- the buffer bolts should. be locked m such a pos1-
--
NOTE: - This check can . best be made
by
means of the m~~tenance - h~dle,-~ith - _
the safety pin rel?trammg th_e closing springs.
If the gap is under the required minimum. it is
- usually possible to form the arcing contacts and
obtain the re_quired dimensions. 'FO form ~e con-
tacts, place a piece of conchnt approximately
two
feet long, over the contact and form the contact
either forward or backward. If the proper dimen-
sions - are still not obtained the movable arc-
ing contacts should be replaced.
If it has been necessary to make-any adjust-
ments while obtaining proper _ contact sequence,
the contact wipe and pressure must be checked, -
and adjusted, if necessary.
CONTACT GAP (Fig. 6)
When· the breaker is open, the gap-between
the movable and stationary contacts should be
between 2 5/8 in. and 2 3/4 in. The gap may
be adjusted · by varying the number of buffer
-tion that th~ buffer bolt may be rotated fre~ly.
REPLACEMENT OF CONTACTS
(Fig. 6)
-.
-Stationary A~cing Contads (2, Fig. _6)
(1, Fig. 7) -
1. Remove the upper plate by removing two
screws .(1). On the -AK-75 and -100 r~move ~e
.top contact Qlock (25, Fig. 7) andremoveinsulation
(3, Fig. 7). __
-.
2. Loosen screws holding spring. -(5)
3• .- Remove pin (3) freeing the stationary con-
.
tacts and springs (22). · ·
4. Install new springs and stationary arcing
contacts in reverse order. ·
5. Adjust contact wipe and
pressure. (See
ADJUSTING
CONTACT WIPE AND PRESSURE).
,,

GEK-7303 Low Voltage Power Circuit Breakers
I l
STATIONARY "ARCING
I
COOTACT
· I .
2. P1N (STATIONARY ARC I NG
I
25
CONTACT) --
I 3.lNSULATI
OO
I
24
4. ID.ABLE ARCf'.lG CO'JT ACT
4A. STA T. NTERMEDIATE
23
CON'lllC T
5. MOI.AB.E MAN CONTA CT
22
6 SHOULDE RE D PIN
4
7. LNK
21
a PIN (ARCING
CONTACT
LINK)
5
20
9. INSULATING LINK
I Q PIN(INSll.ATING LINK)
IO A. A.O J US T ING PLATE
19
II . PI N (S IDE .LI NK)
12.CLEVIS
18
13. CL E VI S PI N.
14.
LOWER STU D
17
15. POLE UNIT BASE
16
16. SPRING (MA IN MOVABLE
CONTACT)
17 . PIN(MOVAEl.E MA IN
COOTACT)
5 -
1a P1N (M OV ABLE
C ONTACT)
ARC I NG
4 19 SI
DE LN<
2Q SPR IN G( STATIONARY
MAN CONTA C T)
2i . ~ ( STATIONARY)
ARC IN G CONTACT
--
22 . Uff>ER STUD
2 3. PIN(STAT I ONAR Y- MAIN
CONTACT)
24. STATICNARY MAl'l
CONTACT
25 . TO P COOTACT BLO CK
Fig . 7 (215D174) Pole unit · assembly -AK-75 and AK-100 .
The .movable
arcing contacts (4) should be
replaced when the stationary arcing contacts are
replaced .
.
1. Separate the front frame from the back
frame as described underSEPARATION OF FRONT
AND REAR FRAMES.
2. Remove
pins (8) and (19) and withdraw
the contacts.
·
12
3. Reassemble parts in reverse order .
Stotio~ory,lntermediate and Ma in
Conta d1 (Fi g. 6) _ .
1.- Remove stationary arcing ctonacts as de.;.
scri bed above.
2. Remove
screws (27) and remove bracket
which holds ~in (25) in place •
3. Remove . main-and intermediate-contact .
stop (20A) which h.olds
the lower part of stationary
contac t. Removal will be facilitated if the force
on the contact springs (21) is neutralized. This
can be accomplished by operating the breaker
with the maintenance handle, with the sa!ety· pi n·
in place, until the load on the contact stop is
· relieved. · ·
4. Loosen
the ha rdware -which fastens the
upper stud to the pole unit base until the contact

Fig. 8 (8014678) Front view of back frame
assembly -AK-2-50
1.
Stationary Arcing 6. Crossbar
Contact
7.
Series Overcurrent
2.
Movable Arcing
Device
Contact 8. Movable
Inter-
3.
Stati9nary Main mediate Contact
Contact 9.
Stationary Inter-
4.
Clamp
_mediate Contact
.
5.
Movable Main
Contact :
spring load on pin (25) is relieved.
5. . · Remove pin (~5i and screws (27) and
lift out contacts.
~- - Reassemble contact.s in reverse . orger,
being careful to replace the intermediate contact
in th~ proper position. ·
Movable Intermediate and
_ Main Contacts (F1g. 6)·
· 1. Remove the movable arcing contacts as
described above.
2. Loosen spring (17).
·
3. Remove braid if present by removing screw
at bottom of contact. · ·
4. Slide link (12) to the side and off of p4l
(7).
5. Slide · pins (7) and (18) far enough to the
sid~ to allow the movable intermediate contacts
to be replaced.
6. Reassemble parts in reverse order.
Always check contact wi pe and pressure follow-
Low Voltage
Power Circuit Breakers GEK-7303
Fig. 9 (8039669) Front view of back frame
·. ·· assembly - AK-3-50
1. Power Sensor Coil Assembly
. 2. Disconnect Plug ·
·
3. Tr;msformer Taps in Amper~s
ing contact replacement ! .
(See ADJUSTING CONTA_CTWIPEAND PRESSURE).
OPERATING - MECHANISMS
ELECTRICALLY OPERATED .AK-50, -75 ·
and -100; MANU~L AK · -50
. The ele ~ trically operated · mechanism includes
a
motor and a gear reduction unit, which charges·
the closing
springs (16, Fig. 10) through a crank
shaft (14, Fig. 10). The crank shaft ha~ an arin
with a roller (12, Fig. 10) which rides on the
closing
cam (2, Fig. 11). The position·of this
closing cam roller is shown in · Fig. 11A, 11B,
and
llC. The closing cam is . connected to the
center-pole unit through a clevis and through a
.
crossbar it controls the opening and closing
of the
contacts ~m all pole units.
Chargi ng the Closing Springs (Fig. 10)
1. The mec~anism in position is shown in ..
Fig. llA.
2. The motor turns the crank (10) which
is mounted on the output shaft of the gear reduc-
tion unit. The charging roller, which is on the
face of
the crank, has paddle arm (11) bearing
on it.
13

GEK-7303 Low Voltage Power Circuit Breakers
~
FIG ·IIA
· ~C>IANSM N t.1111:lN" BEFORE
RESETTING AS SHOWN IN . FIG.- IIB
FIG.- 116
~CHANSM N RES€T POSITlCN
_5
6
7
1.
Pin
Z.. Bushing
3, Bracket
4 . Indicator
5. Bracket
6. Frame
7, Crank Roller
8, Gear Reduc ..
tion Unit
9. Motor
10, Crank
15
14
13
·12_
II
IO
··- ~-
11, · Paddle
lZ., Closing Cam
Roller
13. Closing Cam
Arm
1'4: Crank Shaft ·
15. Spring Charg-
ing Arm
16. Closing Spring
17, Push Rod
18, Clip
Fig. 10 (541E304) Closing spring
·· and chargin g mechanism
3. As the crank turns; the roller pushes the
paddle
arm upward, there~y chargi~ the closing
springs through the spring charging arm (1 5)
of the crank shaft.
4. As the .charging roller approaches dead
center a cut-off switch opens, de-energizing the
motor circui t.
2
3
FIG.-IIC
tJE:CHANSM N a..osED POSITl()'.I
(CLOONG SPRf'lG ClSOtARGED)
1. Spring
z. .• Cam
3. Link
4 . Reset Spring
4A, · Spring Adjusting Nuts
5. Prop
6. Adjus . ting Screw
7. Adjusting Screw Stop Pin
8. Prop Return Spring
9. Roller
10. Trip Latch
11. Trip Shaft
lZ.. Clevis Pin
13. Clevis
14. Latch Buffer Stop
(Bronze Material)
15. Roller
16. Prop
13
~2
()
··· --9
-8
·7
6
5. The breaker is now ready to c lose when .
a closing signal
is given.
Fig. 11 (541E305) Operating mechanism
Clo si ng the halter
Electrically Operated (Fig. 10)
6. With the breaker resting at the precharge
·position, the trip latch may. or may not be in the
reset position. This depends on.the position of
roller (15, Fig. llB) with respect · to the cam
(2, Fig . 11B).
14
1. With the mechanism in theposition described
·· above and the closing springs charged, applying_
a
closing signal · will cause the mo tor to co ntinue
to charge the closing springs allowing the mec~-
anism to reset, u·not already resP.t, to the posi-
tion shown in Fig. UB .

Fig. 1i (8018989) Rear view of fronnrame-
AK-50 showing cam shaft locking plate
being loosened
~ 2.. As the crank . roller (7) passes its top
dead-center position, (maximu.m spring charge
position) the closing springs are free to discharge.
Crank (10) can be overdriven independently of the
motor so - that roller (7) assumes its bottom dead-
center position without restraint. :-
·
3. As the springs discharge, the rotation of
the
crank shaft '(14) causes roller (15, Fig. 11)
to rotate cam (2, Fig. 11) and raise clevis (13,
F.ig. 11).
Prop (16, Fig. 11) holds cam (2, Fig .
llC) in this position ~
4. Raising
clevis (13, Fig. llC) closes the
breaker contacts through the pole base linkage.
Tripping the Breaker (Fig. 11)
·Operation of -any of the trip devices rotates
the trip shaft (11) which ;µlows the trip latch (10)
to release the latch prop (5). This allows the
forces of the· contact and opening springs to
reposition
the operating mechanism linkage to
the
position shown in Fig. llA, In this position,
the operating·
cycle may be repeated.
Adjustments (Fig. 11)
All adjustments should be made with the opera-
ting
mechanism · in the reset position as shown in
Low Voltage
Power Circuit Breakers GEK-7303
' .. .. '; .. ~ .. ':. ... ~. ·· :·· ·•.-
•1: .
.. .!:.:
Fig. 13 (8018984) Rear view of front frame-
AK-50 showing cam shaft locking plate
~nd cam shaft removed -
Fig. llB. (The mechanism should be reset by
manual operation with_the safety pin in place
and with
roller (15) clear of cam-(2).
1. The gap between.the trip latch (10) .and the
roller (9) of the reset latch should be between
1/64 in , and 1/32 in. This adjustment can be
obtained by
turning sc . rew (6).. - · -
2. · The center line of the trip latch (10)
should
pass through the center ofthe roller (9). The
latch
buffer stop on the mechanism frame can
be adjusted by loosening the retaining screws to
reposition the latch with respect to the roller.
3. The . distance between ·the roller on link
(3) and prop (5) should be between 1/64 in. and
1/
32 in. To obtain this gap, advance or retard
the nuts (4A) on -the bottom of the ~d ~ing
.the reset spring (4).
Replacement
When replacing the operating mechanism, refer
to the section titled SEPARATION OF FRONT
AND BACK FRAMES under MAINTENANCE in
these instructions.
The motor is mounted on the side of the g ear-
15

GEK-7303 Low Voltage Power Circuit Breakers
reduction unit and through a worm gear and a
planetary
g~ar train drives the crank (10, Fig. 10)
with a reduction 1000:1. To remove the
motor
and gear-reduction unit,_ proceed as follows:
1• . Remove the
front frame (see SEPARATION
OF FRONT
AND R~AR FRAME.)
2. .Remove closing springs and crank-shaft
as illustrate~ iii Fig.- 12 and 13.
3. Disconnect the
leads from motorandremove
the-wires attached to
gear unit housing.
4. Remove four bolts at the bottom of the
front
frame and one bolt at top of gear reduction
unit. The.
motor and gear unitmay n!JW be removed.•
NOTE : If it is desired to replace only the
motor unit, disconnect the
motor . leads-and
remove only the hardware fastening
it to the
.- -gear-reduction unit. When removing the motor
· only, the front
frame should be placed front
· side down to prevenJ.the oil escaping from the
. ·
gear unit. ·
The
gear .reduction unit contains 4 ounces of
oil
similar to Atlantic Refining Company's Grade
HFS No. 3. ·n should not be necessary to add
or · change oil except when the gear'.'.'reduction
unit-and
motor are disassembled•.-·
QUICK CLOSE BREAKER · .
ADJUSTMENTS .
The quick close breaker basically differs from
the standard breaker in that ~e p~echarging
_operati<;m
is extended to and slightly past the top
dead- center position ofthe closing spring assembly.
As _.!tie springs start .to discharge~to close the
bre_aker, the discharge operation
is arrested by
~ pi:ap and latch arrangement. The subsequent
closing operation
is accomplished· by tripping
the -latch to release the prop which in turn allows
the springs
to continue the interrupted discharging
operation and close the
breaker.
The gear reduction unit for the standard breaker
is ·not interchangeable with the gear reduction
uniLon the quick
close unit because the quick
close
gear reduction unit employs a slip clutch
to relieve the
pressure that would otherwise
be . exerted between the output crank plate and
the prop. . ·
After the·closing springs have been completely
charged and the prop and latch
system are pre-
venting closure of the breaker, the closing opera-
tion may be .accomplished by energizingthe closing
relay.
thni the control relay contacts, or man-
ually- by depressing the push to close lever which
mechanically displaces the latch to allow the
break~r to
close. · .
. . .
On drawout breakers an interlock between the ··
breaker and enclosure
requires the springs to
be discharged before the breaker can be removed
from the
enclosure.
16 .
.' 'c"
Fig . 14A ·
Quick-Closing Release Latch - Fig. 14A
Adjust the engagement of the roiler on the latch
to 1/8
11
±1/64" by turning the screw "A". After
adjustment is set, lock the bolt with the hex nut
"B". Adjust the clearance between the latch and
the
roller to 1/32+0-1/64 by turning the screw "C".
D
Fig. 14B
Release Arm Adjusting - Fig. l4B
Adjust release arm screw "P" so that the stroke of
the armature of the closing solen<:>id releases the
roller from the latch with a minimum of 1/32"
over-travel. ·Check.by using 1/32" GO and 3/32"
NO · GO gauge between armature · and magnet.

Fig. 14C
Release Shaft Stop and Switchette - Fig. 14C
Adjust
screw "E" to 1/32" clearance between
screw and lever with clearance on release arm
ta.ken up by pressing lever lightly forward. ·
Adjust switchette operation by adding washers
"F" under · cotter pin, · so that contact is made
when armature is adjusted as shown above.
The control relay or (X) relay is located on
the
left side of the front frame channel. It may
be removed by disconnecting the wiring, loosening
the (3) two mounting screws and lifting it slightly
to admit the top mounting screw through the
keyhole mounting,
in general, the entire - relay
should be replaced rather than changing coils
and contacts.
The anti-pump relay is located on the left
side of the front channel above the control relay.
The connections to this relay are soldered. Re-
mo~al of . the relay is straight forward. When
re-mstallmg use extreme care to avoid shorting
contact points of different voltage potential with
solder of flux.
The closing· control relay consists of a strong
box solenoid with sufficient linkages to operate
the remotely located D switches.
Stored-Energy Manual Mechanism (Fig. 15) ·
AK-50-75-100
This breaker is equipped with a spring-charged
stored-energy mechanism similar to the mechanism
Low Voltage Power Circuit Breakers GEK-7303
used on theAK-50, -75 and-100 electrical breakers.
The closing springs (5) are charged by operating
·· the manual closing handle (22) on the front of the
breaker, instead of the closing motor as is the
case with the electrical breaker. Closing this
breaker is accomplished by pumping the operating
handle !mu complete cycles, first counterclockwise
through 120 degrees from its normal vertical
position and then clockwise back through 120
degrees from its normal vertical position and
then clockwise back through 120 degrees. When
approximately 70 degrees of the fourth clockwise
stroke have been completed, the closing springs,
which have been charged during the previous
strokes ot the closing handle, are driven over-
center and the breaker closes.
This mechanism consists basically of a closing
spring assembly, ratchet wheel and output crank
assembly, handle shaft and pawl assembly, and
the closing handle.
Closing the Breaker (Fig. 15)
The first stroke of the closing handle causes
the ratchet pawls (21) attached to the handle shaft
(23), to engage the first tooth of the ratchet wheel
(17), thus beginning to char ge the closing sprin gs.
The subsequent closing handle strokes perform the
same function as the pawls (21) engage the teeth
in the ratchet wheel (17), thus rotating the ratchet
wheel and output crank (32) andcompletely charging
th _e closing springs . This rotation of the ratchet
wheel and output crank is in a counterclockwise
direction from the lower · position, through slightly
more than -180 degrees, to a position just beyond
dead center. In this position the closing springs
are free to release their energy, closing the breaker
at a high speed. · .
Inserting the Safety Pin (fig_. 15}
1f it is desired to slowly close the breaker
contacts to check contact wiEe-and sequence,·
operate the closing handle 3 1/2 complete cycles
as described above. At the end of the fourth
counterclockwise stroke and before performing
the fourth clockwise stroke, insert the safety
pin (3) into the hole (4) in the guide rod (6),
thus preventing the closing springs (5) from
releasing their energy to close the bre~er contacts.
Replacement (Fig. 15)
1f it 'is necessary to replace any of the mech-
anism parts, the following total procedure is
recommended. This procedure may be. halted
at the step required to replace any particular
part:
1. · Install the safety pin (3) as described.
above.
2. Separate the front and rear frames as
described under "SEPARATION OF FRONT AND
REAR FRAMES" "in the "MAINTENANCE" sect.ion
of
these instructions.
.17

GEK-7303 Low Voltage Power Circuit Breakers
l---+---+-; H-++-- - 6- --- - -- -1-;.-.-'i- -ll
y.,_-- 7
I .
; §Ji
:j
I,
ii
II
ii r
:i :!
II ~- /' , Jl
L ..~ ; ""'- ·· -··-, '--- ·· - ·
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·Fig. 15 (669D805) Stored-energy manual closing mechanism charged position AK-2
1 •. Upper Spring Pin 11. Output Crank Roller 21. Ratchet Pa~ls
·2, Safety Pin Holder 12. Thrust Bearing 22. Manual Closing Handle
·
3. Safety Pin and Chain 13. Shims 23. Closing Handle Shaft and Pawl Asm.
4. Safety Pin Hole . 14. Groove Pin 24 . Roll Pin
5. Closing Springs 15. Nylok Screw 25. Main Closing Crank
· 6, Guide Rod 16. Ratchet Wheel Shaft and Asm. 26. Pawl Buffer Stop
7. Pawl Springs 17. Ratchet Wheel 27. Butter stop Shims
·1. Front Escutcheon 18. Side Plate Shims 28. Buffer Stop Support
9, Front Bearing Plate ~ 19. Side Plate Mounting Bolts 29. Handle Return Spring
O. Bearing Plate ;Mounting Bolts 20. Be~ring Side Plate 30 . Mechanism Roller .
· 31. Lower ~nrinO' 'P in ,,,, '"'-· .... ··• ,... ___ ,.

GEK-7303 Low Voltage Power Circuit Breakers
6 5 4 3 2
1. Springs
2. Insulation
3. Stationary Contact
4. Pin .
5. Screw
6. Movable Contact
7.
Pin
8. Buffer
· 9•. Crossbar
10. Adjusting Plate
11. Bolt
12. Buffer
13. Screw
14. Shims
15. Bolt
16. Pin
17. Pin
13 14
Fig. 17 (227Dl74) Field discharge c~ntacts (center pole)
When the breaker is tripped, theopeningsprings
pull
crossbar (9) downward, opening the breaker's
outer poles. As the crossbar movesdownward, link
(A) rotates about a fixed center (17)", collapsing
toggle links
(B) and (C) upward, therby closing
center-pole contacts through connecting
link (D).
Link (C) consists of two links riveted together,
forming a single
triangular ·link.
Contact Adjustments
Measurements
For contact measurements and adjustments
of the two outside poles of the
breaker, refer
to POLE UNIT ASSEMBLY.
Contact measurements of the center-pole field
discharge contacts should be made on the left
contact and be within
the following limits:
1. Contact wipe, 3/16 in. to 7/16 in.
2. Contact
pressure, · 10 lb. to 16 lb.
3. Ga_p between contacts when center pole is
open, 1 1/2 in. to 1 3/4 in.
4. Overlap ·between the center-pole contacts
and the
arcing contacts of the outer poles, 3/16 in ··
to 7/16 in. _ · •
Measurements of the center-pole contact wipe
20
and pressure may be made by following the same
procedure as outlined for the standard pole unit
in POLE UNIT ASSEMBLY:· Overlap of the center-
pole contacts and the outer pole arcing contacts
may be checked by the following
procedure:
. -.
1. Remove arc quenchers (see ARC QUEN-
CHER). · . .
2.
Insert safety pin in push rod. (See Fig. 3
under MAINTENANCE.)
3.
Operate closing me~hanism with mainten-
ance handle until
arcing contacts of outer poles
just touch.
4.
Measure distance between forward edge of
left stationary contact of center pole and surface
of insulation block behind contact.
5. Continue to operate maintenance closing
handle
until center-pole contact opens fully.
6. Repeat measurement described in step 4.
Difference betweenmeasurementsindicatesamount
of
overlap.
Adjusting Center-pole Contact Wipe
and Overlap ·{Fig. 17)
If measurements reveal either incorrect center-
pole contact wipe or incorrect overlap of confacts,
adjustments should be made by the following
procedure:

. 3. Remove the closing spring assembly by
removing ·. the upper and lower spring pins (1, 31).
-. .
4. Remove the right ·hand bearing · side plate
(20), and the side plate shims (18) if present, .by
removing four mounting
bolts (19), thus allowing
the main closing crank (25) to be removed.
5. Remove the closing handle (22)byremoving
two
set screws threaded in same hole.
6. Remove the front escutcheon by removing
four scre ws holding it to the front frame center
support.
7. Remove the handle return spring (29) by
unhooldng
either end of the spring.
8. Disconnect the top end of each pawl spring
(7).
9. Remove · the roll ~in (24), thus allowing
the closing handle shaft . (23) and pawl assembly
(2~) to be .re.moved~
JO. Remove the ratchet wheel (17) and its
assembly (16) by removing Nylok* screw (15)
and
thrust bearing (12). If shims (13) are present
they must also be removed.
11. Remove front bearing plate (9) by removing
three mounting bolts (10) accessible from thefront
of the breaker. The mechanism is now completely
disassembled. It is not recommended that any
of the
subassemblies removed during the above
operation be further disassembled in the field.
Replacement sub-assemblies should be obtained
from the factory.
12. To reassemble the mechanism, reverse
_the procedure described above. :
NOTE: When
reassembling tpe mechanism the
adjustments listed below should be checked at
. the appropriate . time of ·reassembly. The
appropriate time for each adjustment is in-
dicated in the adjustment text. ·
Adjustments (Fig. 15). ·
Frequent adjustments to the mechanism sh~uld
not be required. If · the mechanism has been
disassembled, it will be necessary to check the
following adjustments: ·
1. It may be necessary to . add shims (13)
to reduce the end play.of the ratchet wheel shaft
(16). · An end play of 0.010 to 0.020 of an inch
is recommended. Shims should be obtained from
the factory.
2. It may be · necessary to add buffer stop
shims (27) to the buffer stop (26) to provide a
clearance of 1 /64 to 1/32 inch between the pawls
(21) and the buffer stop, when the pawls are
touching the ratchet wheel teeth extending a max-
* Tra _ de-mark of Republic Steel Corp.
Low Voltage Power Circuit Breakers GEK-7303
imum distance from the center of rotation of
.. the ratchet wheel (17). This measurement should
be made while operating the closing handle during
the four spring charging operations and before
the closing springs are reassembled~
3. The - ratchet pawls (21) should operate
freely throughout the closing strokes. .They
should engage
the ratchet wheel teeth . near 'the
end
of each counterclockwise and clockwise stroke
of the closing handle with a definite clicking so und,
indicating a
free non-binding operation. After
the clicldng sound is detected, the closing handle
should
have a minimum overtravel of 1/2 in. or
3 1/2 degrees, measured at the end of each handle
stroke •..
4. · The groove pin ·· (14) in the front of the
ratchet wheel assembly (16) must be assembled
in a manner that Will allow Nylok screw (15)
to be tightened securely . A clearance · of 1/64
to 1/32 in. should exist between the front of the
groove pin and the rear surface of the Nylok
screw head.
Other adjustments . to the closing and operating
mechanisms, such as · complete contact and la tch
adjustments, may be made by following the pre-
vious. ly d~scribed instructions for the AK-50, -75
and -100 breaker mechani sms .
FIELD DISCHARGE
CONTACTS .
FIELD
WINDING
FIELD
SWITCH
DISCHARGE •
RESISTOR .
)
Fig. 16 (4 _15A845)· Typi~al connection diagram
AKF· MECHANISM (Fig. 17f .
The Type AKF breakers are two-pole breakers
with field discharge contacts placed in the center
pole. When this br~aker is ·opened, the field
discharge contacts close, thus connecting an ex-
ternal discharge resistor across the field of the
generator or m otor. When the breaker is closed,
the field discharge contacts are opened. See
Fig. 16 for a typical circuit connection.
19