GE AKR-3-50 User manual

MAI NTE NANCE MAN UAL t t nc t u de s s u ppte ment8Fi#3;
POTVEN CIRCUIT BNEAIIERS
TYPES AKR.3/3A-50
AND AKRU-3/3A-50
GEilERAr @ ErECTRlC

CONTENTS
GENERAL DESCRIPTION. .
General
Breaker Types
Mounting
Fused Breakers.
Breaker Ratings
Breaker Description . . . . .
RECEIVING, HANDLING, AND STORAGE
Receiving and HandlinC . . .
Storage
BREAKER OPERATION
Putting the Breaker in Service
Drawout Breakers
Breaker Insertion (Fig. 3)
Breaker Withdrawal
Stationary Breakers
Pre-service Check
Operating the Breaker
Manual Closing
Electrical Closing
Openlng the Breaker
Interlocks
Closing Spring Interlock (Figs. 6A and 68). .
Racking Mechanism Interlocks (F'ig. 8)
Optional Interlocks
Accessories . . .
Shunt Trip
Undervoltage Device
Static Time-delay Undervoltage . . .
Electric Lockout Device
Auxiliary Switch
BeII Alarm
BREAKER MAINTENANCE.
Safety Precautions
General
Arranging the Breaker for Slow Closing
Lubrication
Replacement and Adjustment of Components and Accessories . . .
Mechanism (Figs. 12, 13, and 14) . . . . .
Mechanism Replaeement (Figs. 15 and 16) . .
Latch Adjustment
Manual Handle Adjustment
Contact Maintenance
Contact Replacement (Fig. 17)
Contact Adjustment
Components and Accessories .
Auxiliary Switch (Fig. 18)
Shunt Trip and Undervoltage Device (Figs. 19 and 20). . .
Maintenance of Static Delay Device for Undervoltage (Figs. 21 and 22) . .
Electrical Control C omponents
Bell Alarm/Lockout FiS. 26).
Drawout Mechanism and Interlocks . . .
AKRU-50 Fused Breaker
Fuse Replacement
Open Fuse Lockout Device (Fig. 32)
Power Sensor Overcument Trip Device
False Tripping Caused by Faulty Ground Fault Operation .
Testing Current Sensors
Replacement
Magnetic Trip Device (Figs. 33 and 38) . .
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Selective Tripping 36
Time-current Curves 3?138

IOW-VOLTAGE POWER CIRCUIT BREAKERS
TypEs AKR-3/3A-so AND AKRU_3 /ga-so
GENERAT DESCRIPTION
GENERAT
Low-voltagepower circuit breakers are used for
controlling andprotecting power circuits inthe low-
voltage range (usually up to 600 volts). In servins
this function, they are a means of safely switchin[
loads and automatically clearing circuits when ab-
normal conditions occur. Among these conditions,
the more common are short circuits and sustained
overloads and undervoltages.
The proper use, care, and maintenance of these
breakers is a prime safety consideration for the
protection of personnel, as wellas a means of mini_
mizing equipment damage when faults occur. per-
sons who apply, use, and service these breakers
will acquire the knowledge they need by gaining the
information contained in these instructions.
BREAKER TYPES
Ali of the subject breakers are of the "quick_
make, quick-break" descripiion, having the feature
of storing energy in a closing spring for quick re_
lease in closing. In closing, some energy is trans-
ferred to an opening spring to be used sJbsequenilv
for fast tripping.
hdividual breakers may vary in how they are
morrnted, how they operate, how they are applied
and in other categories as shown in Table L.
Fig. 1. (8041849) AKR-50 Manual breaker
IABTT I
Fig. 2 (804t9i9) AKRU-S1 Electrically operated
breaker
Drawout
Stationary
Manual, Fig. I
Quick-close Electrical, Fig.
Type of
Overcurrent
Trip Device
These inslruclions do nol pvrport lo covsr oll dcloils or voriolions in egurpmenl nor lo p.rovide for everyposible conlinge ncy lo be mel in connection
wilh instollotion' operdlion or moinlenonce. should furlher informolion bi iesired o, tno[ii'pirtirutor pioblams arise which ore nol covered sufficienlly
for lhe purchoser's purposes, rhe moner shourd 6e referrd ri rhe c.^irilii".tr;"-t;;;;r:"

GEK-731O, Power Circuit Breokers
IY\OUNTING
Most breakers produced are of the "dralvout"
type. These breakers are equipped with features
which make them easy to install in or withdraw
from their associated switchgear equipment. These
features are a racking mechanism (whichfacilitates
inserting andwithdrawing thebreaker unit) aad pri-
mary and controL power disconnects which connect
and part automatically. Interlocking devices are
included. Drawout breakers of the same rating and
type are interchangeable in their various locations
in the equipment. This helps breaker maintenance
in that spare breakers can be "plugged in" while
breakers are being inspected or serviced.
The "stationaryf'breakers are designed to be
mounted on a framework or panel, with mechanical
fasteners being used to secure the breaker frame
and make powef connections. If control power con-
nections are needed. a suitable terminal board is
supplied.
FUSED BREAKERS
Fused breakers are given the extra letter "LI"
in their model identification number. Type AKRU
breakers are not interchangeable with standard gen-
eral-purpose drawout breakdrs since their enclos-
ures must be modified to provide the extra space
required for the fuses.
All fused breakers are equipped with an opened
fuse lockout device (OFLO device). This automa-
tically trips the breaker open when any of the three
fuses open. It alsolatches thebreaker inthe opened
position until a resetting device is manual.ly oper-
atdd. This should not be done until the expended
fuse is replaced. This arrangement eliminates the
possibility of allowing the circuit to have only one
phase energized.
BREAKER RATINGS
Type AIG-50 breakers are 1600-ampere frame
size breakers. This represents the maximum con-
tinuouscurrent theymay carry. This current value
is modified by the rating of the overcurrent trip
device with which the breaker is equipped. The
lovest available rating of the Power Sensor trip
device is 200 amperes.
As to voltage ratings, the breakers may be ap-
plied up to 600 volts, ac.
Short circuit ratings vary with the system vottage
on which they are applied and whether they are
equipped with direct-acting instantaneous over-
current trip devices. See Table 2.
BREAKER DESCRIPTION
IGnowledge of how the breaker is designed and
how it operates will enable the purchaser to make
proper use of the breaker and to avoid mistakes
il its operation. Specific directions on adjustments
and maintenance procedures will be treated later.
The three main functional components of a
breaker are its mechanism, an assembly compris-
ing the conductive members, and the ilterrupter.
The mechanism unit is designed to receive en-
ergy, store it, and later (when called upon to do so)
deliver it to close the breaker's contacts. It must
be able to reverse its commitment to close the
breaker at any point upon the activation of an auto-
matic trip device (i. e., be "Trip-Free"). Finally,
it also must be able to trip open a closed breaker
quickly enough to minimize arc erosion and in such
a manner as to effect proper arc transfer to the
arc runner.
The current-carrying members of the breaker
are assembled on the back frame, which provides
the mechanical support required and also the in-
sulating structure needed. The conductive mem-
bers are the studs for external connections, mova-
ble and stationary contact sets, pivots for t}te mov-
able contacts, and provision for mounting the cur-
rent transformers.
The interrupter components are, in addition to
the arcingcontacts, the arc runners mounted on the
back base and the removable arc quencher assem-
blies.
In addition to these basic components, a breaker
may be equipped with any combination of many ac-
cessories and interlocking devices.
IABI.T 2
Three-phase Short-circuit Rating
42,000 amps
50,000 amps
50,000 amps
42,000 amps
50,000 amps
65,000 amps

Power Circuit Breokers, GEK-7310
RECEIVING, HANDLING, AND STORAGE
RECEIVING AND HANDLING
Each breaker is carefully inspected and packed
before shipment. Immediately upon receipt of the
circuit breaker, an examination should be made for
anydamage sustainedin transit. If damage or rough
handling is evident, a damage claim should be filed
immediately with the transportation company and the
nearest General Electric Sales Office should be
notified.
It is expected that due care will be exercised
during unpacking and installation of the breaker so
that no damage wi.ll occur from careless or rough
handling, or from exposure to moisture or dirt.
Check all parts against the packing list to be sure
that no parts have been overlooked.
STORAGE
It is recommended that the breaker be put into
service immediately in its permanent location. If
this is not possible, the following precautions must
betakento insuretheproper storage of the breaker:
1. The breaker should be carefully protected
against condensation, preferably by storing it in a
warm dry room, since water absorption has an ad-
verse effect on the insulation parts. Circuit break-
ers for outdoor switchgear should be stored in the
equi.pment only when power is available and the
heaters are in operation to prevent condensation.
2. The breaker should be stored in a clean lo-
cation free from corrosive gases or fumes. Par-
ticular care shouldbe taken to protect the equipment
from moistwe and cement dust, as this combination
has a very corrosive effect on many parts.
CAUTION: IF THE BREAKER IS STORED
FOR ANY LENGTH OF TIME,IT SHOULD
BE INSPECTED PERIODICALLY TO SEE
THAT RUSTING HAS NOT STARTED AND
TO ASSURE GOOD MECHANICAL CON-
DITION. SHOULD THE BREAKER BE
STORED UNDER UNFAVORABLE AT-
MOSPHERIC CONDITIONS, IT SHOULD
BE CLEANED AND DRIED OUT BEFORE
BEING PLACED IN SERVICE.
BREAKER OPERATION
PUTTING THE BREAKER IN SERVICE
DRAWOUI BREAKERS
The mechanism used to provide the mechanical
force required to overcome the resisting force of
the disconnects on Type AKR breakers is mounted
onthebreaker rather than in the drawout enclosure.
This mechanism is referred to as the "drawout"
mechanism or the "racking" mechanism. It is a
unit subassembly and can be added to a completely
assembled breaker without doing any disassembly
work on the breaker.
This drawout mechanism consists of a crank-
shaft and a power screw which operates it. Rigidly
fastened to each end of the crankshaJt is a crank
arm having an open slot which engages a fixed pin
in the equipment enclosure. As the crankshaJt ro-
tates, the crank arms, acting on the stationary pin,
cause the breaker to move with respect to the breaker
enclosure. The crankshaft is driven as the power
screw is turned in an internally threaded trunnion
supported by a centrally located crank on the crank-
shaft. The power screw, or jackscrew, is turned
by means of an external handle in the form of a
crank. This has, on its end, a square socket which
will engage the square end of the power screw in the
breaker. A sliding cover in the escutcheon must
be moved aside so that the handle may engage the
screwshaft end. Turning the crank handle in a
clockwise direction moves the breaker into the con-
nected position. The reverse of this causes the
breaker to move out.
BREAKER |NSERI|ON (FtG. 3)
The procedure for inserting a breaker into its
drawout enclosure is as follows:
1. Before inserting the breaker, apply a light,
even coating of D50H47 grease to the silver-plated
bars inthe enclosure whichengagethe primary dis-
connects of the breaker.

GEK-731O, Power Circuif Breokers
I. Spreader
2. Drawout Rail
3. Breaker Rail Pins
4. Slots in Rail
5. Trip Button
6. Racking Shaft Arrns
7. Housing Racking Pin
' B. Rail Latch Link
9. Racking Position Indicator
10. Movable Inner Housing
Fig. 3. (8041582) Inserting the breaker
2. Position the breaker in front of the cubicle
intended to receive it and engage the lifting device.
A special "spreader" is provided as shown in Fig.
3. The hooks of the spreader are placed in the
forward square-shaped holes in the breaker side
sheets for standard breakers, and inthe holes near-
est the back for AKRU fused breakers.
3. Open the door of the breaker encloswe, and
unlatchandpull forward one of the rails inthe sides
of the cubicle.
4. Raise the breaker until the rail pins in the
breaker sides are a few inches above the slots in
the extended rail.
6
5. Extend the second rail.
6. Align the pins on the breaker with the slots
in the rails and carefully lower the breaker, allow-
ing the pins to enter their slots. Make sure the pins
go all the way down to the bottom of the slots; re-
move the lifting device.
7. Make sure the breaker is open by pushing in
the trip button. While holding in the trip button,
move the sLiding cover aside and then engage the
racking handle.
8. If itispossibletoturn the handle in a counter-
clockwise direction, do so until the stop is reached
and remove the handle. If the handle does not turn,
remove it. This step is taken to align the arms on
the ends of the rackingshaftso that theywill engage
the pins in the housing. If the racking mechanism
has not been operated while the breaker is out of
the encloswe, the arms will be in theright position
to engage the pins andthis stepwillnotbe necessary.
9. Make sure that latches on the ends of the ex-
tended rails are in the unlatched position, and by
pushing on the breaker, roll it as far as it will go
into the enclosure.
10. Put the latches on the ends of the rails into
their locked position.
11. Push in on the trip button, move the sliding
cover to the right, and engage the racking handle.
12. Rotate the handle clockwise. After about five
revolutions, thebreaker will be in the test position.
The indicator in the left upper side of the compart-
ment will show when this position is reached. If
the control circuits are energized and the breaker
is electrically operated, the motor will run when
the secondary disconnects engage. This will occur
on about the third turn of the handle. The motor
will run, charging the closing spring, until the cut-
off switches are actuated,
13. h the test position, the secondary discon-
nects, which carry the control. voltage, are con-
nected; however, the primary disconnects, which
connect the power circuits, are still widely separ-
atbd. At this point, electrical control devices on
the breaker may be operated for the purpose of
testing.
14. Further clockwise rotation of the racking
handle causesthebreaker to travel to the connected
position, which also will be shown on the indicator
in the equipment compartment. During this phase
of the racking operation, the spring-loaded fingers
of the primary disconnects on the breaker will en-

Power Circuit Breakers, GEK-731O
gage the stationary bar in the equipment enclosure.
The opening of these fingers against the force of the
springswill cause a noticeablyhigher load require-
ment in the racking effort. This will very quickly
fali off to a lesser force requirement to the end of
travel, at which point a stop will be encountered.
About three handle turns will be required between
the peak force requirement and reaching the stop
which ends the movement. Upon reaching the stop,
the handle should be removed without any rever-
sal of the handle motion. Approximately 24 turns
on the handle are required for the complete rack-
ing cycle.
15. The first time the breaker is introduced into
the enclosure, it should be completely withdrawn
and the marks of the disconnect fiagers on the
grease on the stationary bars examined. These
tracks marks should indicate no less than 1/4-inch
engagement. The maximum amount that can be
attained is g/16-inctr.
BREAKER WITHDRAWAL
1. Trip the breaker open, hold in the trip but-
ton, and move the sliding cover in the escutcheon
aside to the right.
2. Engage the racking handle and crank in a
counterclockwise direction.
3. ApproximateLy 24 turns of the handle wiII
complete the racking-out operation and bring the
breaker to the disconnected position. This will be
shown on the indicator in the compartment and will
be evident to the person operating the mechanism
because a stop will be encountered beyond which no
further movement can be made. Towards the end
of the racking cycle, the "closing spring interlock"
willbe activated. This willcause theclosing spring
to discharge, but will not close the breaker.
4. To withdraw the breaker completely, open the
latches onthe ends ofthe rails, and pull thebreaker
out of the compartment. The breaker may now be
Iifted off the rails by the lifting device.
STATIONARY BREAKERS
Stationary breakers are intended for separate
mounting on a framework or switchboard panel, or
in an enclosure of the customerts own design and
construction. They are the same breaker unit as
the drawout type; however, they do not have the
drawout features, namely, the racking mechanism
and automatic disconnects and interlocks.
Careful consideration should be given to the se-
lection of a location for mounting stationary break-
ers. They should be situated so that they can be
easily reached for operation and maintenance, with
enough surrounding free space so that working in
the area is not troublesome. If it is possible, the
Iocation chosen should bedry andclean andnot sub-
ject to extreme variations of temperature.
Mounting the breaker involves bolting the frame
of the breaker to its supporting structure within the
switchboard or enclosure, making power connec-
tions tothebreaker studs, andmaking control power
connections to the breaker terminal board and arx-
iliary switch terminals, if these are required. Four
mountingholes are required forthe hardware which
fastens the frame to its support.
These mounting holes must all be in the same
vertical plane. If they are not, strain may be im-
posed on the breaker structure which could ad-
versely a-ffect the operation of the breaker. The
ouiline drawing which is furnished with the breaker
gives information on preparing a mounting structure
and a cover or door suitable for preventing access
to live parts of the breaker.
Another requirement of the supporting structure
for the breaker is that it be rigid enough to with-
stand the forces that result from high momentary
and short-circuit currents to which thebreaker may
be subjected. Connectingbus or cable must also be
supportedadequately to resist these forces. points
of support for buswork or cable must be close
enough to the breaker so that no appreciable strain
is imposed on the breaker's studs.
Manual breakers must be located so that clear-
ance is provided for the sweep of the handle when it
is operated. This requirement will be 11 inches
to the right from the centerline of the breaker, or
2-l/2 arches beyond the right edge of the breaker
frame.
Since eachupper studof thebreaker is composed
of two separate members, the connections to the
stud must provide a solid connection across the two
parallel stud members, as well as an external con-
nection. All stationary breakers will be shipped
with connector bars already fastened to both upper
and lower studs. These bars will accommodate
cable connectors or busbars. If an external bar
connects across both halves of the upper studs, the
connectorb:rrs may bedispensed with. hthis case,
the end of the connecting bus should extend in to-
wards the breaker base no more than 5/8-inctr be-
yond the centerline of the fastener hole.
Control connections on stationary breakers are
made to a terminal board located in the upper left
frontarea of thebreaker (front view). The terminal
board may have 6, 10 or 14 points. This will be
governedby the requirements of the control scheme.

GEK-731O, Power Circuit Breokers
If the breaker has an auxiliary switch, external
connections may be made directly to the terminaLs
of the switch.
PRE-SERVICE CHECK
Before putting the breaker into service for the
first time, it would be well to make a cursory ex-
amination and a preliminary check of the operation
of the breaker. This may be carried out with the
breaker on a workbench or on the extended rails of
an equipment drawout compartment. The check
should consist of the following:
1. Attach thedrawout racking handle to the shaft
onthebreaker afterpushing thetrip button and slid-
ing the cover aside. Turn the handle clockwise un-
til it stops. This will deactivate the various inter-
Iocks which otherwise would keep the breaker from
closing.
NOTE: Remember, later, that this me-
chanism must be set back to i,ts original
position before the breaker can be in-
serted in the equtpment.
2. Remove the arc quencher from each pole and
examine it for the possibility of broken or missiqg
parts. Do not replace the arc quenchers until after
the preliminary examination is completed.
3. Charge the closing spring. If the breaker is
manually operated, turn the handle eounterclockwise
as far as it will go (140 degrees), then reverse the
motion and rdturn it to the vertical position. If the
breaker is electrically operated, use the mainte-
nance handle, Fig. 5, to turn the camshaft which
charges the ciosing spring.
NOTE: It probably nill be necessa',ry to
align the triangular socket in the handle to
make it go on the end of the shaft.
4. Close the breaker. The manual breaker is
closed by pushing the CLOSE button in the escutch-
eon. The "quick-close" electrical breaker may be
closed by pulling forward on the armature of the
closing solenoid which is located beneath the me-
chanism and may bereached throughthe large rec-
tangular opening in thelower end of the escutcheon.
This maybe done safelysince none of the parts that
move in closing are in this area. (See Fig. 64,.)
Observe the difference between the position of
the stationary contacts when the breaker is opened
and when it is closed. The main contacts should
8
move in ("wipe") at least 1/16 inch. If they do not
seem to do so, and careful measurement confirms
this, refer to the section of these instructions en-
tiiled "CONTACT MAINTENANCE. "
5. Make swe that a-ll the devices used for trip-
ping the breaker open Erre operable. Manually ac-
tivate thesewith thebreaker closedto establish this.
Devices in this category are the manual trip, the
overload devices, the shunt trip, and the under-
voltage device.
6. If the breaker is a drawout breaker, check
the operation of the interlock devices. Make sure
that Iifting interlock pin (3), Fig. 4, will trip the
breaker and that the sliding cover (1), Fig. 8 can-
not be opened if the breaker is closed. Check that
the closing spring wiII discharge automatically if it
is charged, and the drawout racking handle is cralked
as far as itwill go inthe counterclockwise direction.
7. Replace the arc quenchers, clamping them
securely.
8. The electrical operation of electricai break-
ers should be checked when control power is avail-
able, with the breaker in the "test" position in the
drawout equipment compartment.
OPERATING THE BREAKER
A breaker may be equipped to operate either
manually or electrically. Both types of operation
result in the same fast-closing movement as far
as the contact action is concerned. The variation
is in the rpay energy is stored in theclosing spring,
and how i.t is released.
'NANUAt CLOSING
Manually operated AI(R breakers are constructed
with front-mounted handles. Handle operation re-
sets the mechanism and fully charges the closing
spring. A complete charge is accomplished in
either cranking the handle through one cycle (135-
degree swing) or three cycles (50-degree swing).
The CLOSE button, mounted on the escutcheon, is
used to close the breaker contacts and the TRIP
button to open them.
If equipped with a closing solenoid, a manual
breaker may beclosed remotelyby a control switch
or relay. Before this can be done, however, the

Power Circuit Breokers, GEK-731O
1. Arc Quencher Clarnp
Fi.g. 4. (8041848)
Z. Clarnp Screw 3. Breaker Position Interlock
Breaker with bqrriers and arc quenchers remoued
Fig. 5. (8041831) Using maintenance handle to turn camshaft

GEK-731O, Power Circuit Breokers
closing spring has to be charged by hand. The
closing solenoid is an optiona-l accessory and is not
supplied unless specified in the breaker order.
ELECIRICAL CTOSING
Applying control power immediately energizes
the closing motor on electrical breakers. Cutoff
of the motor circuit does not occur until a-fter the
spring is completely charged and overcenter. The
spring is mechanically held from discharging until
the closing circuit activates a solenoid which re-
leases the holding latch.
Apush-button closing switch may be provided on
electricalbreakers. This feature, however, is pro-
vided only ifspecified in the breaker order. If sup-
plied, it is located inthe right side of the escutcheon.
When in service, all electrical breakers are
closed either by energizing the closing circuit re-
motely, or at the breaker location by operation of
the push button switch in the escutcheon (if ttre
breaker is so equipped).
OPENING THE BREAKER
A closed breaker will open (trip) whenever the
trip latch (11), Fig. 12, is moved off the roller on
the secondary latch (14). A number of trip paddles
are mounted on the trip shaft, one for each tripping
device.
INTERTOCKS
Some interlock devices are required by Industry
Standards and Certifying Authorities; others are
optional and intended only for special applications.
The standard interlock devices described in the fol-
Iowing paragraphs are used only on drawout break-
ers. Stationary breakers have no required inter-
locks.
cLoSrNG SPRTNG INTERTOCK (F|GS. 6A AND 68)
Closing spring interlocks help to provide pro-
tection against the hazard of a completety charged
and overcenter spring being accidentally released
after the breaker has been withdrawn from its en-
closure. Drawout breakers have their ciosing
springs fully charged prior to closing and thus re-
quire this sa-fety feature.
Figure 6A shows how the interlock is activated
by the racking mechalism. As racking arm (1)
approaches the "disconnect" position, crank (2),
10
Fig. 6A. (227A8290) Closi.ng spri.ng interlock
\-
10
a\
t\
\'\
f..
I
I
'l
l. Racking Arrn
2. Crank
3. Le:'er
4. Spring Release Lever
5. Closing Solenoid
6. Roller on Ratchet
7. Closing Spring
8. Adjustable Link
9. Blocking Plate
10. Sliding Cover
Fig. 68. (22748289) Blocking plate
through connecting linkage, causes lever (B) to ro-
tate clockwise, actingagainst the closingspring re-
lease lever (4). This is the same lever which is
operated by the closing solenoid (5).
When the closing spring is automatically dis-
charged by the interlock, it does not cause the
breaker to close. The contact arms remain mo-
tionless because the mechanism is held "trip-free"
by plate (9), Fig. 68, which blocks the return of
the sliding cover (10) to its normal position unless
\ri
/- "l
a\^. .rm
\ \N
\\l
It\
tl
12

Power Circuit Breokers, GEK-731O
the breaker is in the "test" position or the "con-
nected" position. This limits motion to those parts
within the mechanism frame, which are relatively
inaccessible, and minimizes the possibility of an
accident.
RACKING'NECHANISIYT INIERLOCKS
(FtG. 8)
A drawout breaker connected to a power circuit
must not be allowed to move unless the breaker's
contacts are open. This requirement is met by
automatically locking closed the sliding cover in
the escutcheon when the breaker is closed.
Unless this cover is moved, the drawout rack-
inghandle cannot be used. Lockingisaccomplished
by link (2), Fig. 8 which moves down into a notch
in the cover ia response to the main shaft being in
the closed positi.on.
Another aspect of the interlock arrangement is
that the openingmovementof the slidingcover cams
the manual trip button into the tripped position'
keeping the breaker "trip-free", so a closing cycle
of the mechanism will not cause any closing move-
ment of the contacts. This condition will prevail as
Iong as the drawout handle is engaged.
Another interlock featwe is the breaker position
interlock. This makes thebreaker "trip-free"while
moving between the "test" position and the "con-
nected" position. When the breaker is at any point
between these two positions, a link on the breaker,
which is coupled to the trip shaft, is displaced by
the "ramp" cam in the side of the breaker housing.
This holds the mechanism latch out of position and
keeps the breaker open even if the closing springs
are discharged. See Fig. 4.
OPTIONAT INTERTOCKS
The optional interlocks are key interlocks and
door interlocks. On drawout breakers. these de-
vices are mounted in the equipment and are part of
the breaker enclosure. Padlocks may be used to
Iock the t'inner" house in the "disconnected" po-
sition.
On all breakers, it is possible to use padlocks
to lock the breaker open by placing the shackle of
the padlock through the trip button hole and out the
slot in the side of the escutcheon. This holds the
trip button inthe depressedposition and the breaker
cannot be closed.
Stationary breakers may be equipped with a key
interlock as illustrated in Fig. 7. This illustration
shows the end plate assembly of the main shaft when
the breaker is open. Pin (3) is held away from the
path of the lock bolt (4), which can be extended, aI-
-t-
1 . Lock
2. End Plate
3. Pin
4. Lock BoIt
5. Pin
6. Link
\
\\
\\
I
i
)
\
6
11
Fig. 7. (134C2184) Key inteflock for stati.orwrl breahers

GEK-7310, Power Circuit Breokers
l. Sliding Cover 2. Locking Link
Fig. 8. (134C2179) Drawout interlocks
3. Trip Button
lowing the key to be removed. Extending the bolt
makes it push against pin (5). Through the linkage,
this moves the breaker latch, and makes it impos-
sible to close the breaker.
When the breaker is closed, the metal plate as-
sembly is away from link (6) and the torsion spring
causes pin (3) to move into the path of the lock's
bolt, which cannot then be extended.
ACCESSORTES
Accessories available for use on the AIG-50
breakers are, in most cases, the same devices
used throughout the entire line of AK breakers.
Minor differences in mounting and location may
exist, but most of the devices themselves are iden-
tical.
L2
Maintenance operations, such as adding, re-
placing, and adjusting these components wili be
dealt with in the maintenance portion of these in-
structions; only a description of the device and the
function it serves will be dealt with here.
SHUNT TRIP
The shunt trip device opens the breaker when
its coil is energized. An frA't auxiliary switch,
which is closed only when the breaker is closed, is
in series with the device coil. Connections are
made to the external tripping source through sec-
ondary disconnects on drawout breakers, or to the
arxiliary switch and terminal board on stationary
breakers.
On the breaker, the shunt trip is mounted on the
bottom of the breaker frame in a central location.

Power Circuit Breokers, GEK-731O
UNDERVOLTAGE DEVICE
The undervoltage device trips the breaker when
its coil is de-energized. The leads of the coil are
connected directly to secondary disconnects or to a
terminaL board. Under normal conditions, the coil
remains energized and the breaker may be closed.
"Drop out" of the armature, with resultant
breaker tripping, occurs when the voltage is re-
duced to Iess than 60 percent of the rated voltage.
An open armature willrenderthe breaker incapable
of closing. The armature "picks up" ald allows
closing, if the voltage is 85 percent or more of its
nominal value.
If the breaker is disconnected, and for some
reason the breaker is to be operated manually, the
undervoltage device may be tied or wired down so
that it wiII not cause tripping.
MAIN SHAFT
(BREAKER CLOSED)
Fig. 9. (0134C2181) Holding link on electric
lockout deuice
STAT]C TIIYIE-DEIAY UN DERVOTTAGE
In addition to the instantaneous undervoltage
tripping device mounted on the breaker, the static
time-delay undervoltage includes a separately
mounted time-delay unit. Its diagram is shown in
Fig. 21. If the.aic control voltage is anyvoltage
other than 208/240V ac, a control power trans-
former (also remotely mounted with respect to the
breaker) must be used. This must have a minimum
rating of 100 volt-amperes.
When installed, the voltage to be monitored is
connected across terminal.s No. 1 and No. 2 of the
static delay box. The coil of the tripping unit is
connected across terminaLs No. 4 and No. 5 of the
static box through the secondary disconnects of the
breaker. The secondary disconnects to be used
will be shown on the breaker wiring diagram.
No more than one undervoltage tripping device
should be used in conjunction with one static time-
delay unit.
The static time-delay undervoltage can also be
furnishedwitha thermotector controlunit, as shown
on wiring diagram, Fig. 22. Overheating of motor
windings causes the thermotector, imbedded in the
motor windings, to open. This de-energizes the
undervoltage device on the breaker and drops the
motor load.
ETECTRIC LOCKOUT DEVICE
The electric lockout device utilizes an under-
voltage device to keep the breaker from resetting
its mechanism i-f the breaker is open and the under-
voltage device coil is not energized. The breaker
thus cannot be closed unless voltage is on the coil.
Once the breaker is closed, Ioss of voltage wiII not
trip the breaker because, in the closed position, a
mechanical link is used to hold down the armature
of the device. See Fig. 9. This arrangement pro-
vides a means of electrically interlocking two
breakers so that they cannot be closed at the same
time. Each undervoltage coil may be wired in
series with a '8" auxiliary switch contact on the
other breaker for cross-interlock purposes.
On each breaker having an electric lockout, an
arrangement is made which will allow breaker
closing with the coil de-energi-zetl. This is pro-
vided to aLlorr '?start-up" on "dead" systems. Fig-
ure 10 shows this device. The push slide shown is
located in the opening in the lower part of the es-
cutcheon. The breaker doormust be opened to gain
access to it.
HOLD.IN
13

GEK-731O, Power Circuit Breqkers
/-lr \\ '"/,/ ',
i.i;) Y ".
\-:/ // \. \ \
+-i!Lr-
i+.++-l
T l-*r 1
tr ll
'-L- -rL'
\@w
AUXITIARY SWITCH
AII electrically operated breakers and manual
breakers having shunt trips are supplied with aux-
iliary switches. Depending upon the requirements
of the breaker's application, the switch may con-
tain from two to six stages. UsuaIIy, each stage
has one ttAtt contact and one ttBtt contact. ttAtt con-
tacts are openedor closed as the breaker is opened
or closed. "B" contacts are the reverse of this.
Drawout breakers have their auxiliary contacts
wired to secondary disconnects; stationary breakers
may be wired directly to the switch terminals.
BELI AIARM
This device is used to give a remote indication
of the breaker's having tripped open through the
PUSH
IN TO
DEFEAT
LOCKOUT
action of one of its automatic protective devices.
It will not be activated by manual tripping or the
action of the shunt trip. A remotely mounted pro-
tective relay energizing the shunt trip will not re-
sult in the remote alarm action.
The bell alarm circuit may be turned off by
pushing in the manual trip or by energizing the
shunt trip. In the latter case, a normally open
contact of the bell alarm switch must be wired in
parallel with the "A" auxiliary switch contact in
the shunt-trip circuit. Closing the brea-ker will
also turn off the alarm.
The bell alarm device may be equipped with a
Iockout iink which will lock the breaker open until
the bell alarm device is reset.
The bell alarm is not a standard device and is
supplied only when specified on the breaker order.
Fig. lQ. Q134C2182) Arm.ature holdi.ng mechanismfor
electric lockout deui.ce
t4

Power Circuil Breokers, GEK-731O
BREAKER TIAINTENANCE
SAFETY PRECAUTIONS
WARNING: BEFORE INSPECTING oR
BEGINNING ANY MAINTENANCE WORK
ON THE BREAI<ER, IT MUST BE DIS-
CONNECTED FROM ALL VOLTAGE
SOURCES,BOTH POWER AND CONTROL,
AND THE BREAKER MUST BE IN THE
IIOPENII POSITION. ALSO, BEFORE
WORK IS DONE ON THE BREAKER, THE
CLOSING SPftING IS TO BE MECHANIC-
ALLY DISCONNECTED FROM THE CAM-
SHAFT OF THE MECHANISM. WITH THE
SPE/NG DISCONNECTED, THE BREAKER
MAY BE CLOSED SLOWLY, USING THE
MAINTENANCE HANDLE AS SHOWN IN
FIG. 5.
GENERAL
Breakers should be cared for through the im-
plementation of a systematic maintenance program.
A periodic inspection routine is recommended. How
frequently an inspection is made of an individual
breaker will dependonthe circumstances of its use.
Itwould be well to inspectany breaker at least once
a year. If it is frequently operated, or installed in
an area of high humidity or a dusty, dirty atmos-
phere, the frequency of maintenance inspections
should be increased. Under extremely bad condi-
tions, inspections might be monthly.
Amaintenance inspection should include an over-
all visual check and the observation of a few clos-
ing and opening operations. If the breaker is elec-
trically operated, at least one electrical operating
cycle should be observed. A close inspection should
be made of contacts and the inner surfaces of the
arc quencher side plates and inner components.
Contact wipe should be checked as described inthe
maintenance section dealing with contacts.
If dirt, grease, or any other foreign material is
found on any parts of the breaker, it should be re-
moved by a thorough and careful cleaning. Insu-
latingsurfaces shouldbe checked for any conditions
that could cause a loss of insulating properties.
If a breaker has interrupted a short circuit, its
contacts should be inspected.
It is good policy, if a number of breakers are in-
cluded in an installation, to have one or more spare
breakers to install in the place of breakers requir-
ing maintenance work. In such cases, a rotating
program, providing for a periodic withdrawaL from
service of each breaker in turn for inspection and
maintenance, is an excellent means of establishing
a high level of service reliability. Maintaining a
reasonable stock of recommended spare parts will
be a good means of ensuring that maintenance work
will be done quickly.
Maintenance work will, in most cases, consist
of cleaning and replacement of worn or damaged
breaker components. Mostof thefollowing instruc-
tions will comprise descriptions of replacement op-
erations and any adjustments that may be required
after new parts are installed. They will be equally
useful for adding accessories to breakers not orig-
inally equipped with them.
NOTE: Breakers oaithdrawn from equip-
ment must haae their drawout mechanism
cranked to the "connectedt position to
operate nonnally. See Step 7 of ttPre-
Seruice Check" instructions.
ARRANGING THE BREAKER FOR
srow crosrNG
Figure LL shows how to disconnect the closing
spring from the mechanism's camshaft. A l/2-
inch wrench is used to remove the hex-head bolt in
(8041 8 33) Dis cormecting closing s pring
15
Fig. 11.

GEK-731O, Power Circuit Breokers
the bottom of the springassembly. This part of the
operation must bedone onlywhen the closing spring
has been discharged and is at its shortest condition
of extension. After the bolt has been removed, the
ratcheting maiatenance handle may be used to turn
the camshaft, closing the breaker slowly. The
breaker should be operated only to the point where
the roller on the ratchet stops against the prop link.
(See Fig. 6.A. ) At this point, the manual Ctose Uut-
ton must be pushed, or the armature of the closing
solenoid must be pulled, to move the prop away.
When this is done, the slow closing action may be
continued.
Closing the breaker slowly, while observing the
action of the mechanism and contacts, is a good
way of judging the correctress of mechanical and
contact relationships. Some of the maintenance
procedures described later will involve operating
the breaker in this manner.
TUBRICATION
In general, the circuit breaker requires mod-
erate lubrication. Mechanical bearing points and
sliding surfaces should be lubricated at the regular:
inspection periods with a thin film of GE lubricant
D50H15. Sliding silver-plated contact surfaces
should be lubricated with GE lubricant Db0H4?.
Hardened grease and dirt should be removed from
latch and bearing surfaces by using kerosene.
CAUT|ON: ALL .EXC,ESS LaBRICANT
SHOULD BE REMOVED TO AVOID ANY
ACCUMULATION OF DIRT OR DAST.
NOTE: The use of cotton waste to wipe
bearing surfaces should be auoided, as
the cotton raaelings may become entangled
underthe bearing surfaces and destroy the
surface of the bearing.
On drawout breakers, the contact surface of the
disconnect studs should be greased with GE Grease
Specification D50H47.
REPTACEfiIENT AND ADJUSTMENT
OF COfiTPONENTS AND ACCESSORIES
tvtEcHANtstvl (FlGs. 12,13, AND l4)
The mechanism closes the breaker when the
cam rotates. (Counterclockwise in Figs. 12 and
13; clockwise in Fig. 14. )
l. Closing Spring
2. Prop
3. Carn
4. Carnshaft
5. Carn Roller
6. Holding Pawl
7. Ratchet Wheel
B. Driving Pawl
9. Gearrnotor
l0. Trip Shaft
1 1. Trip Latch
12. Insulated Coupling
13. Main Shaft
14. Secondary Latch
15. Opening Spring
t2
lt
t0
4 5 6 7 I
Fi.g. 12. (108D8131) Electrical breaker mechalnism
16

Power Circuit Breokers, GEK-73\O
l0
ll
t3
I. Closing Spring
2. Prop
3. Carn
4. Carnshaft
5, Carn Roller
6. Holding Pawl
7. Ratchet Wheel
B. Driving Pawl
l0 . Trip Shaft
11 . Trip Latch
12. Insulated
Coupling
I3. Main Shaft
14. Secondary
Latch
I5. Opening Spring
16. Manual
Adjustrnent
Link
Fig. 13. (108D8130) Manual mechanism
TRIPPED
2. Prop
3. Carn
4. Carnshaft
5. Carn Roller
CLOSED
Fig. 14. (108D8132) Mechanisnt
RESET
10. Trip Shaft
1 1. Trip Latch
I 2. Insulated Coupling
I3. Main Shaft
14. Secondary Latch
t7

GEK-731O, Power Circuit Breokers
Fixed centers are shown shaded in Fig. 14.
The prop is free to rotate on the cam shaft. It
holds the cam roller in place after the cam roller
has been raised by the cam. A light tension spring
holds the prop in the position shown, but d.llows it
to move out of the wav of the cam roller.
On electrical breakers, the eccentric output
shaft of the gearmotor turns the camshaft by caus-
ing the driving pawl to reciprocate, advancing the
ratchet wheel.
Fast cam action occurs when the closing spring
goes over center, unless it is held by a prop link
(not shown) acting against a stop on the ratchet
wheel. Figures 12 and 13 show the closing spring
in a position just over center.
When the manual breaker handle'is raised coun-
terclockwise, a strong torsion spring rotates the
driving pawl assembly until
the camshaft. Returning th
position pulls the chain on
rotating the camshaft.
t engages a notch on
handle to its normal
the sprocket segment,
'YlECHAN ISIVI REPTACEMENT (FrGs. rs AND 16t
Figure 16 shows the mechanism sub-assembly.
If components of this unit require replacement, a
new complete sub-assembly must be installed.
If a general overhaul involving extensive com-
ponent replacement is undertaken, it may be con-
venient to separate the major breaker sub-assem-
blies as shown in Fig. 15. If this is done, the
secondary disconnect assemblies should be removed
first.
The ratchet wheel may be replaced as an indi-
vidual component by driving out the sprirg pin which
fastens it to the camshaft.
18
Fig. 15. (108D8127) Assembly of frames, arc quenchers, and secondany disconnects

Power Circui| Breokers, GEK-731O
Fig. 16. (8041918) Mechani.sm subassembly
LATCH ADJUST'VIENT
The reset position of the trip latch (11), Fig. 14
is set byan adjustment screw on the left side of the
mechaaism frame. The adjustment is correct if
three and one-half turns of the adjustment screw
causes a closed breaker to trip. If this check is
made, the screw must then be set back, or un-
screwed, three and one-half turns.
'VTANUAt HANDTE ADJUST'NENT
The manual handle adjustment is made by means
of the adjustable link (16), Fig. 13. The length of
this iinkis controlled byturninga double-ended stud
in the center of the link. A hex section in the mid-
dle of the stud allows the engagement of an open-
enA ?/16-inch wrench.
The handle can be out of adjustment either by
having the link too long, in which case it wiII not
extend the closing spring enough to go over center;
or it can be too short and not engage the camshaft
on the up-stroke of the handle.
If the handle stroke does not fully extend the
sp::ing, the maintenance handle can be used to com-
plete spring charging. The breaker can then be
closed and opened and the handle adjustment made.
With the wrench engaged, and looking down on
the breaker, turning the wrench clockwise will
lengthen the link. The opposite motion will shorten
it. The rarge of the adjustment is 300 degrees with
the best setting in the middle of the range. Each
stroke of the wrench imparts 15-degrees movement
in the confined space available.
CONTACT ftIAINTENANCE
CoNTACT REPTACETVIENT (FlG. 17)
Brea-kers whose application requires frequent in-
terruption of high currents may eventually require
the replacement of their contacts. The general
rule for determining the need of replacement is the
Ioss of one-half or more of the mass of the contact
tip material. Roughening or Iight pitting of the
contact surface does not indicate any loss of ability
to carry or interrupt current.
The contact arrangement provides sets of two
arcing contacts, two intermediate contacts, and six
main contacts. These are the stationary contacts.
Two movable contact arms act against the stationary
contacts in closilg.
Arcing contacts (1), Fig. 17, are released by
removing the arc mnner (5) and the arcing contact
pivot (6). When reassembling, make sure that the
insulating spacers on the ends of the arcing contact
pin (?)and the insulatingwashers (8)under the lower
arc runner fastening screws are replaced.
htermediate (2) and main contacts (3) are re-
moved by disconnecting their springs. The end
pieces on the springs (9) have a small hole for the
purpose of engaging a spriag puller having a wire
diameter of 1/16-inch. When the spring is pulled
while holdhg the contact, it may be lifted off the
end of the contact. A contact is replaced by hold-
ing it in position (with its inner end behind the con-
tact stop) and extending and engaging the spring on
the outer end of the contact.
A spring puller is available for this use and may
be ordered under Cat. No. 016585712G1.
Contact arms are removed by drifting out pin
(10) connecting them to the insulated link and then
removing the fasteners and pins from the pivot be-
low.
When replacing the arms, make sure that all
spacers, springs, and washers are returned to
their original position.
Right angle tru-arc pliers are needed to re-
move and replace the tru-arc retainer on the end
of the pin which connects the contact arms to the
insulated coupling.
19

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.