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
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