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. Installation, Care and Operation of Circuit Breakers and Accessories

TnlE LA-50 AIR CIRCUIT BBEAKER

BOOK BWX-6427

These instructions are not intended to cover all detaj.ls or variations that may be encountered in connection with the installation, operation, and maintenance of this equipment. Should additional information be desired contact the Allis-Chalmers Mfg. Company.

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ALLIS·CHALMERS � MAIUFACTURIIG COMPAIY

CONTENTS

. INDEX TO INSTRUCTION BOOK COVERING

TYPE LA-50 AIR CIRCUIT BREAKER

Part I. General Information

A. Introduction B. Warrahty C. Receiving and Inspection for Damage D. Storage

Part II. Installation and Operation

PAGE NO.

1 1 1 1

A.. Mounting 2 B. Inspection 2 c. Operating Mechanism Check 3 D. Trip Units and Accessory Devices 3 E. Pantograph and Trip Interlock Adjustment 3 F. Energizing the Breaker 4

Part III. Description and Function of Parts

A. Operating Mechanism B. Contacts C. Method of Arc Interruption D. Relays E. Trip Units and Accessory Devices

Part IV. Maintenance, Adjustment and Replacement

A,. General B� Periodic Inspection C. Maintenance Check List D. Movable Arcing Contact E. Stationary Arcing Contact F. Movable Main Contact G. Stationary Main Contacts H. Trip Units and Accessory Devices I. Operating Mechanism { Manual) J. Operating Mechanism ( Hydraulic)

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ALLIS·CHALMEIS <8> MAIUFACTURIIG COMPIIY

CONTENTS (CONT'n) PAGE NO.

Part V. Protective Devices

A. Series Overcurrent Trip Device Assembly Adjustment and Calibration 11

Inspection and Adjustment 13 Maintenance and Replacement 13

B. Thermal Magnetic Overcurrent Trip Device Assembly 14

Inspection and Adjustment 1 5 Maintenance and Replacement 16

C. Overcurrent Trip Flag Indicator and Reset 16

Part VI. Accessory Attachments

A. Shunt Trip Attachment 16 B. Auxiliary Switch Attachment · 17 C. Bell Alarm Switch Attachment 17 D. Mechanical Overcurrent Lockout Attachment 17 E. Undervoltage Trip Device 18

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AUI.S·CHALMEIS • MAIUFACTURIIIG ·cOMPiiY

Figure

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2b

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LIST OF ILLUSTRATIONS COVERING ALLIS-CHALMERS TYPE LA-50

LOW VOLTAGE AIR CIRCUIT BREAKER AND AUXILIARY EQUIPMENT

Description

Hydraulically Operated Breaker

Manually Operated Breaker

1200 Amp Contact Structure

1600 Amp Contact Structure

Operating Mechanism (Schematic)

Wiring Diagrams

Auxiliary Switch

Secondary Disconnect

Hydraulic Operator Assembly

Limit Switch

Shunt Trip Device

Series Trip Device

Thermal Trip Device

Indicator Flag, Mechanical Lockout, .Bell Alarm Switch, and Reset Button for Overcurrent Trip Devices .

Series Trip Curves (Dual Magnetic)

Series Trip Curves (Dual Selective)

T.ime Curves of Series Trip Elements ( S. T. , Lt. & Inst • ) Thermal Trip Curves

Undervoltage Trip Device

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AL:I;IS·CHALMEii <$> ;M'AIUFACTURJIIG COMPAIY

CAUTIONS TO BE OBSERVED IN THE INSTALLATION AND OPERATION OF. THE LA-50 AIR CIRCUIT BREAKER

1. DO NOT ATTEMPT TO OPERATE BREAKER OR INSERT IN CUBICLE UNTIL ALL PACKING TRACES HAVE BEEN REMOVED.

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2. READ INSTRUCTION BOOK BEFORE MAKING ANY CHANGES OR ADJUSTMENTS ON THE BREAKER.

,3. DO NOT INTERCHANGE PARTS OF TRIP DEVICES ... TO DO SO MAY CHANGE CALIBRATIONS.

4. ALWAYS OPERATE MANUAL CLOSING HANDLE QUICKLY AND DECISIVELY - TO HESITATE IN MID-STROKE .MAY CAUSE UNDUE BURNING OF CONTACTS.

5. CHECK CURRENT RATINGS AND SERIAL NUMBERS AGAINST SINGLE LINE DIAGRAM TO ASSURE THAT BREAKERS ARE PROPERLY LOCATED IN SWITCHGEAR AT INSTALLATION.

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INSTRUC.TIONS FOR THE IN£TALLATION AND OPERATION

OF ALLIS-CHALMERS TYPE LA-50

LOW VOLTAGE AIR CIRCUIT BREAKER AND

AUXILIARY EQUIPMENT

PART I GENERAL INFORMATION

&. Introduction. Th e type LA-50 air circuit breaker is one of a line of low voltage air breakers which may be used in metal enclosed switchgear, on open type switchboards, or separately mounted in individual housings. The LA-50 breaker series is composed of two ppera classesi the 1200 ampere class for continuous current ranges of 200 to 200 amperes, and the 1600 ampere class . The Ll-50 air circuit breaker has an interr­upting capacity of 50,000 amperes and a maximum continuous current. rating of 1600 amperes at 600 volts, 60 cycles. For information on other frequencies, the factory should be. -consulted, All LA.-50 breakers are completely· aasembled , tested, and calibrated at the factory in a vertical position and·must be so installed to operate properly. Customers primary connec­tions should be adequately braced against the effects· of short · circuit currents to prevent overstressing the breaker terminals,

· B, Wars:antr . Allis-Chalmers LA-SO air circuit breakers are warranted to e l'ree of defects in material and workmanship for a period ot one year atter deli very to the· ·ori ginal purchase-r.

·This warranty is limited to the turnishins . ot any part which--to our Ja&tistaction has been proven defective�· Allia•Ohaliluars ·will ilot in any case asswae responsibility for allied equipment ot"' any ki�.

_ C, Receivinf fnd Inspection for Damage .�en U-S9 _ _

air circuit breaker an ts associated apparatus !s carefully checked, inspected, and packed at the factory by·workman ex­perienced in the proper handling of electrical equipment. Immediately upon receipt of this equipment, carefully remove �11 packing traces an d examine parts, checking thea against the -packing liat and carefully noting any damagea incurred 1ft tra�sit, If such is disclosed a damage claim should �e filed at once with the tranaportat!on company and Allis-Chalaera notified, Keep instruction books and tags with the breakers,

D, Storage. When breakers are not to be put into -immediate uae, they should be carefully wrapped or coTered to provide protection from plaster or concrete dust and other foreign matter, Abrasive dust in the breaker can cause ex-

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Observe that the manual operating handle ( 2-17) returns from closed �o neutral posit ions automatically by act ion of its return spring ( 2-14) .

Next open breaker by means of manual trip button ( 2-1 ) on front of breaker . The toggle linkage (2-3 7) will collaps e , the contacts will move to the open position freely and rapidly , and the closing mechanism will reset , ready for th e next operat ion. Operating springs (2-4) assist in rapid opening of the contacts and actuate the resetting of t he closing mechanism.

C . Operating Mechanism Check . The operating mechanism is properly adjusted and t ested at the factory , and ordinarily there should be no need for readjustment in the field . If for . some reason , the mechanism fails to latch in the closed po�it ion che ck to be c ertain that all trip devices are reset and not ' interfering with th e trip latch (2-3 1 ) . The trip lat ch should be free to return to its latching position; If the t ri p latch is free and the-mechanism still fails to latch , check to be certain that there are no binds or interferences in the mechanism and that all links and lat ches are fully reset . If breaker is st ill unstable , the trip latch reset spring (2-JO) may be adjusted to increase its r eaction against the latch (refer to Maintanarice Check List , Part IV , S ection C ) . However , befor e changing any adjustments b e c ertain that the trip lat ch engage­ment is sufficient , as outlined in the maintenance check list .

D . Trip Units and Accessory Devices . These it ems also should receive a thorough che ck prior to placing breaker in service to be certain that adjustments are proper and parts are not damaged. Refer to Parts V and V I of th e instruction book for the description of adjustments and funct ions of these devices .

E. Pantograph and TriS Interlock Adjustmen� . This applies only to cubicle mounted reakers of the drawout type . As a closed breaker is racked into position it should trip shortly after it passes the "test position" indicator; At tl)is poi�t. the control circuits will be made , but the primary con­nections will be open , and it will be impossible to close the breaker unt il it reaches the "operating position" indicator. Continue racking breaker in and close it when the operating position is rea ched . Closing should not be affected by t he int erlock mechanism. Then , as the closed breaker is racked out towards the test posit ion , after approximately·5/16 inches travel the breaker should trip . At this point, disconnect fingers {l-14 ) will still b e in full contact with the stationary stud , and it will b e impossible to close the breake r again until the t est pos it ion is reachedo If the me chanism does not �un ction as desc�ibed , refer to the cubicle instru ction book for correc­tive �djustments.

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Thus link ( 15 ) will move to the left and open the breaker contacts (3 ) and ( 4 )o When the me chanism reaches the open posit ion , link { 13 ) ·is released from link {19 ) and the mecha­nism is reset by spring {20 ) to the open posit ion as shown in Fig . 5.

Fig. 4 shows the me chanism in the trip-free position . Since.latch (5) and levers (6 ) and (7 ) are released� center (D) is not temporarily held as in-a normal closing operation. Thus when link (13 ) rotates counterclockwise , spring reaction holds center ( 23 ) fixed and link {14) rotates counterclockwise about center {23 ) . Thus, although link (13 ) goes through its complete stroke , link {15) does not move and the breaker contacts will not close . This action can take place during any part of the closing stroke, causing contacts t o immediately return to the open position even though the hydraulic operator remains energized or the manual closing stroke is completed.

B. Contactso The contact structure for the 1200 ampere class LA-50 is shown in Fig. 2ao The contact structure for the 1600 ampere class LA-50 is shown in Figo 2b. The 1600 ampere class contact structure is the same as the 1200 ampere class contact structure except for the addition of an extra pair of primary disconnect contacts and addit ional conductor material in the contact structureo

The contacts on the LA-50 breaker consist of main current carrying contact s and arcing contactso They are arranged such that contact make and break is by means of the arcing contact s , while the main contacts are not subjected to a�cing. Arcing contact surfaces are clad with a silver tungsten arcing alloy which greatly reduces mechanical wear and arc erosion. The positive wiping action of the arcing contacts, as well as the properties of the contact material, prevents weld­ing and sticking when interrupting high current s. This insures long satisfactory service .

Another feature of the contact structure is the "blow­on" effect produced by the physical configuration of the moving member . This is best shown schemati cally as in Fig. 5o The current path , when main contacts only are parted , is from the arcing contact {5-3) to pivot point (I) , and thence completely around the loop of the main contact to pivot point {F). The mechanical forces produced by current flowing in such-a path tend to hold the arc ing contacts solidly in contact , both in opening and in closing , and thereby prevent premature or un­controlled contact parting or bounceo Both the stationary and the movable arcing contacts have arc runners which lead the arc away from the contact surfaceso This prolongs contact life as well as aiding arc interruption.

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When the Y contacts close the X relay and hydraulic pump motor are deenergized, but the Y relay will remain energized as long as the control switch i:s held closed.· This prevents "pumping" or repeated attempts to close. The control switch must be opened before another closing attempt is possible. The hy4raulic pump motor and the X relay coil are designed for intermittent duty and must not be permitted to rem�in energized any longer than is necessary to close the breaker. The XY relay scheme accomplishes this automaticallY· Fig. (6) shows a typic�l wiring diagram. Although variations ma.y be necessary� ·or other control elements added, to suit a specific app;l.i,cation., llbe basic XY relay arra,pgement will usually be a a deecri·bed. ·

E. Trip Units and Accessory D2v�ees � . .Jleacription and function or· these itell)s· are covereCiti Parts>·V a!ld VI of the instruction book�

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PART IV MAINTENANC�, ADJUSTMENT, AND REPLA�ytENT

A. General. Occasional checking and cl,eS:ni:ng· ·or the breaker will promote long and troublefree service. Oiling and greasing should be done with care because excess oil and.grease tend to collect dirt which ih time might make operat1Qn �luggish and affect the dielectric strength of insulating members. Always refer to the instruction book before removing parts or·changing adjustments. A recheck of the installation inspection (Part II) during maintenance will indicate the o·verall general· cond�tion of the breaker.

B. Periodic Inspection. A periodic inspection·and servicing shoUld be included in the breaker maintenance routine. A semi-annual inspection is usually sufficient, however, in cases where unfavorable atmospheric conditions exist, more frequent inspections are �ecommended. In any case, the total number of breaker oper.ations between servicing should not exceed 500 for the LA-50 breaker. The maintenance check list (Section C) will provide a ready and convenient guide to a thorough and understanding inspection of the breaker. Servicing will be facilitated if a tag �s attached to each unit listing date, operation counter reading, ·date of next inspection, counter reading at next inspection, and serviceman's signature • .

C. Maintenance Check List. The following items are listed for convenience irt maintaining the equipment in the best possible condition. By periodically checking and maintaining. these items, the breakers will provi�e the con\inu�d satisfactory service of which they are capable.

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.. positioning slotted end of spring (2-30) - clockwise to decrease tripping force, and counterclockwise to increase the tripping force .

Trip latch (2-31) engagement on secondary trip lever (2-36) roll should be 1/8" to 3/16". Measurement is from the leading edge of trip latch face to-the line of contact on the latch face. Adjustment is obtained by the positioning of a fixed stop in the mechanism frame.

8. Trip latch roll adjustment. Trip latch roll on screw (2-29) should have 1/32" to 1/64" clearance to trip block (2-34) with the trip block against its stop. Adjustment is obtained by positioning screw (2-29):

9. Reset button. The reset button (14-6) is adjusted to provide.l/16" to 1/6" clearance between reset lever (14-10) on the breaker and trip device reset lever (14-17) with the reset shaft (14-1) on the trip device in the tripped position.

10. Operation counter. The operation counter (2-16} when supplied is actuated by the open-close indicator (2-18) and is adjusted such that the counter arm has same overtravel when breaker is open. ·

11.. Limit switch. With breaker in closed and latched position, the upper conta·cts (10.,8) (10-9·) of limit switch (10-3) should have 1/32� follow-up after contact make. Adjustment is by use of shims (10-7) between switch and mounting pad.

12. Hydraulic operator assembly. The hydraulic operator assembly (Fig. 91 is mounted on the operating mechanism frame (2-19) and held in position by mounting screws l9-4). Energization of the motor (9-6) causes pump l9-14) to move hydraulic fluid from the reservoir (9-13) through the pump and connecting table (9-16) into cylinder (9-2) under pressure. This hydraulic fluid under pressure moves plunger (9-3) up against closing cam ram pin ( 9-9) which in turn closes. the · breaker. The vertical motion of.the plunger compresses plunger return spring (9-15) which returns the fluid back through the connecting tube into the reservoir.

Should readjustment be necessary, the following procedure ·should be used. With the breaker in the closed position, rotate closing h'ndle to take'up all free motion in handle, a clearance of 1-1 16" to 1-3/32" .shoUld· be maintained ·

between the end of plunger (9-3) and contact surfac� of closing cam ram pin (9-9). Remove or add shtm (9-S) to maintain thia adjustment. After this adjustment has been.made, there should be a minimum of l/64H clearance between main closing cam (9-1) and· closing cam overtravel stop {9-lO)(Fig, 9 dimension HA"). With the breaker in the open position there should be a minimum

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H . Trip Units and Accessory Devic es. For maint enance, adjustment , and replacement of these devices refer to Parts V and VI of the instruction book, where detailed instructions will be found.

I. Operat ing Mechanism (Manual). The manually operated mechanism is fastened to the breaker panel frame by eight screws (2-21). Shims (2-22) are used to adjust main contacts (see section IV� C - 5 ) and must not be changed for any other reason . The operator may be removed from the breaker by disconnect ing breaker operating link (2-39) and removing four screws (2-21J, carefully noting amount of shims (2-22). After reassembly , pay particular attention to trip latch adjustments and main contact adjustments to be c ertain they have not changed. Ch eck me cha­nisms for ease of operation and freedom from binds .

J. 0 eratin Mechanism H draulic • The hydraulic operating mec anism is exactly the same as the manual me chanism, with the addit ion of hydraulic cylinder and accessories to accomplish the closing operation. The manual closing means is retained , as in the manually ope rated breaker. The operating mechanism and hyd�aulic me chanism can be removed as a unit as described in Section IV- I ,·after disconnecting the clQsing motor and limit switch leads. Should the hydraulic mechanism be removed from the operating mechanism, it must be carefully readjusted on assembly as outlined in S ection IV - C-12. A. D . C. motor is furnished for use with a direct current source . When the breaker is to be operated from an alternating current source , an A . C . motor is furnished. Thus, rect ifiers and aging resistors are not required.

PART V PROTECTIVE DEVICES

A. S eries Overcurrent Tri Device Assembl Ad ustment and Calibration. eries overcurrent trip devices used on low voltage breakers function to trip the breaker whenever the current through the breaker exceeds a predetermined value. This device includes a series coil , magnetic circuit with two arm­atures, and a sealed oil t ime delay device. This arrangement is varied somewhat on current· rat.ings above 600 amps. on the LA-50, and the LA-75 breakers , in that the trip device coil is not t ied to the lower contact structure , but is l inked to an inductive series coil mounted on the fixed bus in the rear of the breake r . Figure 12 shows the arrangement of the functional components of this device and Figures 15, 16 give the inverse time delay character�stics.

The trip elements available in the vari'ous categories of series trip devices are three in number and calibrated in the following ranges.

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plunger varies the force applied to the time delay device by changing the lever ari;ll and also changing the stroke required for tripping. Each time band, maximum, intermediate or minimum, is marked by a white band indicating the mounting point for the time delay device plunger. All of the band locations are progressive and if desired, intermediate settings may be made between the calibrated points for finer selectivity.

The pickup calibration of the armatures is selected by rotating knob (12-2 ) which moves the calibration label (12-3 ) to the required setting. Adjustment of the calibration label increases or decreases tension in the pickup spring and is factory calibrated for values of pickup current.

INSPECTION AND ADJUSTMENT

The series trip device should be inspected prior to being put in service to see that the pickup calibration and time delay band selections are in accordance with the applica­tion requirements. This device leaves the factory with the following standard settings unless otherwise specified in the purchase order: Long time delay element is set at lOQ%.pickup on the intermediate time delay bandft Short time delay element is set at 750% pickup on the intermediate time delay band. Instantaneous trip element is set at BOO% pickup. Selections other than those already made to the device do not require further testing in that the unit is completely calibrated at the factory. The current rating of the series coil is stamped on the breaker Nameplates and should be checked in applications involving varied current ratings.

MAINTENANCE AND REPLACEMENT

The individual phase series trip device assemblies are mounted on a common base and must be removed from the breaker for maintenance or replacement as one assembly. To remove this assembly, detach the assembly mounting bolts (2-271 and screws (2a-24) holding the series overcurrent coils (12-7) to the contact structure. NOTE: ON THOSE APPLICATIONS ABOVE 600 AMPERE COIL RATING,.THE OVERCURRENT COILS ARE LINKED TO INDUCTIVE SERIES COILS MOUNTED IN THE .REAR OF· THE BREAKER AND: THESE COIL LEADS MUST BE DISCONNECTED TO REMOVE THIS ASSEMBLY. Having removed the assembly from·the breaker each single phase aasembly can then be detached from the common base by the ·

removal o£ four mounting screws (14-15Y·and the reset shaft(l4-l).

To remove series coil (12-7 ) which does not require a single phase disassembly1 detach the four mounting screws (12 -5) holding core assembly (1�-8) in·place and slide the complete core assembly out of the device. The series coil will then slide off the core leg and can be assembled in the reverse steps.

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condition exists in t he series coil {13 -12 ), it causes a similar overcurrent in the secondary coil {13 -9 ) due to the transformer action in the fixed armature {13-16) . This overcurrent condition in the secondary coil generates heat to the spiral wound. bi­metallic element (13-3) by means of the nichrome wire heater coil {13 -2 ) which surrounds this element. The heat generated in the heater coil (13 -2) causes the free end of the.bimetallic element (13 -3 ) to rotate along with cam (13-5 ) which is fastened to it. On overloads, the rotation of cam (13-5 ) is sufficient to release the thermal trip armature (13-19 ) which was previous�y restrained by roller (13-7) working against. this cam. Upon being released, the thermal armature rotates on shaft (13-10) so as. to close the air gap through which it is ele·ctromagneti­cally attracted to the core assembly (13 -13 ) . As the thermal armature {13 -19) closes this gap it picks up and engages the trip block { 2 -34 ) at trip screw {13-14) and acts to trip the breaker as previously described in Section III - A of the operating mechanism. The breaker having tripped the core assembly {13-13 ) is no longer energized which aliows the thermal

· .armature to be returned to its latched position by return spring { 13-18 ). A short time interval may be required to completely reset cam (13-5 ) after trip cycle is completed due to c_ooling of bimetallic element.

Because of the inherent long time delay of this device it is equipped with an instantaneous trip armature {13-21 ) which provides high-overload protection. This instantaneous trip armature is factory set so as to trip the breaker whenever there is an overload of 8 to 12 times normal coil current.

Trip screw (13-14) on thermal trip armature (13-19) is removed for those applications which require the thermal armature to sound a bell alarm on overcurrent conditions, 'but not trip the breaker. Under these conditions the instantaneous trip armature {13-21 ) must have the trip screw (13-14) properly adjusted tor high overload protection. For details concerning reset of the bell .alarm see Section VI - .C under bell alarm. .

INSPECTION AND ADJUSTMENT

The thermal magnetic trip device should be inspected prior to being put in service in the same manner as the series trip device to check that the pickup calibration is in accordance with the application requirements. The thermal·trip device leaves the factory with the following standard settings unless otherwise epecified in the purchase order:

Thermal magnetic trip element ia set at 10� Bickup calibration. Instantaneous trip element is set at 800� pickup. The thermal magnetic trip element may 'be adjusted without further testing as this element has been factory calibrated over its full range, but the instantaneous element would require calibra­tion to change ita pickup value. To adjust instantaneous pickup,

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\ c ontact swit ch i s used to interrupt its c ircuit immediat ely after the breaker is tripped . Each electrically operat ed breaker is equ ipped with a shunt tripping device for remote control . Thi s devi ce is mounted on a bracket on the left side of the me chanism frame as shown on Fig. 1. It includes a c oil, magnet, armature and return torsion s�ring s . Energization of the coil (11-3) causes armature (11-2) to pickup and engage trip bar (11- 4) thereby tripping the breaker . The t orsi on springs (11-1) are used primarily to return the armature t o a n eutral position after the breaker trips. Little or no mainte­nance or adjustment is required on this device. To che ck, move the armature to the pickup posit ion and not e that the trip bar has moved the trip latch as explained in Section III Paragraph A under operating me chanism.

B. Auxiliary Switch Attachment . The auxiliary switch Figure 7 i s of the rotary type and i s stu rdily constructed. This switch is mounted on the operating mechanism frame and functions by direct connection to the breaker m echanism. Elec­trically operated breakers are provided with 2 "a" and 2 "b" (7-4) contact s in this switch, mount ed on the left sid e of the mechanism . Provisions are available for the mount ing of an identical switch on the reverse s ide. "a" switches are closed when the breaker contacts are closed, and "b" switches clos ed when breaker contacts are open . The auxiliary switch contact s are factory s et for "a" and "b" pos it ion, but may be int er­changed in the field-by reassembling the rotor element (7-1) as desired. A moulded bakelite cover l7-3) which snaps on can,be easily removed for c ontact inspect ion.

c. Bell Alarm Switch Attachment . The bell alarm switch (14-8) functions to close an alarm circu it upon automatic overcurrent tripping of the breaker, or by s pecial application may indicate an overcurrent condition by sounding an alarm wi�h­out tripping the breaker. This switch i s a single pole double throw switch mount ed on the outer pha se trip devic e . The b ell alarm switch is actuated by lockout lever (14-9) which .rotat e s with reset shaft (14-1). The rotation of the reset shaft is d escribed under "series trip flag indication" Section V Para­graph C. The rotation of lockout lever (14-9) trips toggle spring (14-16) which holds this lever in the tripped position until reset button (14-6) is actuated to reset the reset shaft. It must be noted that the b ell alarm switch i s reset only by manually actuating the reset button (14-6). Replacement of the b ell alarm switch requires only the removal of two mount ing screws holding switch to the t rip device . On reassembly check to be certain that alarm will sound when lockout lever (14-9) is released.

D . Mechanical Overcurrent Lockout Attachment . The mechanical lockout featur e prevents the circuit breaker from being closed e ither manually or electrically aft er being tripped

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moved and that the armature (18-13 ) slides freely to the breaker trip position without being energized. This device (with time delay) leaves the factory set at 2 seconds time delay, when the voltage drops to zero, unless otherwi�e specifi ed. The time delay device is adjustable, but not calibrated, between 2 ;5 seconds and . 5 seconds. This adjustment is obtained by loosen­ing nut (18-10 ) and positioning time delay device (18-o) on bell crank (18- 5 ) as shown in lFig. 9) . The pick up and drop settings can be adjusted by loosening locknut (18-11) and adjust­ing the pre-compression of springs (18-3) and (18-4)-by turning adjusting nut (18-12) .

NOTE: After making this adjustment, a check should be made to see that the armature still seats firmly on the pole head, otherwise the increased exciting current may-�ause ·the coil to overheat. �

J_une 195 5

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A UXILIARY--( ll SWITCH

LIMIT­SWITCH

I"TERLOCK --( I T RIP BAR

VIEW SHOWING RELAY MOUNTING

(LEFT HAND VIEW)

�------ 18�--------� IIOCATIIIG LIGHTS --(13 a PUSH BUTTO"

(SPARE) AUXILIARY

SWITCH

10 )--U"DERVOLTAGE TRIP

PROVISI0"--(11 FOR PADLOCK � �ti� ��--HYDRAULIC CLOS I"G

I I I DEVICE - MOTOR - a PUMP AS SEMBLY

9 l--HYDRAULI C CLOSING DEVICE- CYLIM>ER

a I'LUMIEI FIG-I HYDRAULICALLY OPERATED

BREAKER 2-28-55 71-540-024

·i"DIA HOLE PROVIDED FOR BI!KR LIFT

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THESE TERMINALS HOT FURNISHED ON BRKRS 1200 AMPS 8 BE LOW

141-- PRIMAIIY DIS CONNECT

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ALLIS·CHALMERS � MAIUFACTURIIG COMPANY

MANU AL TRIP I RESET BUTTON 1'- CAM FOLLOWER 2l SCREW

PROP LATCH SPRING 16. OPERATIONS COUNTER (WHEN REQUIRED) 28 OVERCURRENT TRIP DEVICE

PROP LATCH IT IIANUAL CLOSING HANDLE 29. TRIP LATCH ADJUSTING SCREW I MANUAL TRIP

OPENING SPRING 18. OPEN-a.osE INDICATOR LATCH AtlJUSTING SPRING (ACTUATED BY Q) I LATCH PIN 19. OPERATING MECHANISM FRAME :sa TRIP LATCH ADJUSTING SPRING

MAIN CLOSING UNK 20. INDICATOR LINK 31. TRIP LATCH UFT PIN 21. SCREW 32. PRIMARY TRIP LEVER

YOKE 22 CONTACT ADJUSTING SHIM 33. MANUAL TRIP I RESET SPRING

LOCKING SCREW 25. FRONT BARRIER 34. TRIP BLOCK BREAKER PllOLOCK LATCH 24. PHASE IARRIER 3:5. MANUAL TRIP BLOCK

MANUAL CLOSING CAM OVERTIIAVEL STOP PIN 25. ARC CHUTE 36. SECONDARY TRIP LEVER

MANUAL CLOSING CAM UNK CLOSING HANDLE RETURN SPRING

26. PANEL ASSEMBLY 31 MAIN TOGGLE LINK

1200 AMP. PANEL SEE FIG 2a 36. ROCKING LINK

2000 AMP. PllNEL SEE FIG 2b 59 CONTACT OPERATING LEVER

40 CAM FOLLOWER

FIG 2 MANUALLY OPERATED BRE AKER APRIL 5, IV55 71·540·030 www .

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!···MOVABLE ARCING CONTACT 2--MOVABLE MAI\I CONTACT 3··- STATIONA RY ARCING CONTAGT 8 ARC RUNNER 4·-· FRAME 5·-·SCREW 6--·SCREW 7·-· STATIONARY MAIN CONTACT BLOCK a--SCREW 9-·· LOWER STUD CONNECTOR IO···MAIN CONTACT SPRINGS 11-··MAIN CONTACT FINGER 12·-·SHIELD

13--HINGE CONTACT SPRINGS !+··SCREW 15-··HINGE CONTAGT BLOCK 16--HINGECONTACT ANGER 17··-RETAINING RING 8 HINGE PIN 18-·-MAIN OPERATING SHAFT 19· --cONTACT OPERATING LEVER

20--A RCING CONTACT SPRING 21··-ARCING CONTACT INSULATION 22-SPRING WASHER

23--RETAINING WASHER 24··-SCREW

23

1; I II

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.IUMI"EJi *"'WWafloENT (800TO 1200 AMPS)

FIG. 2A

25--� 26--.IUMPER 27- SERIES COIL (COILS 200 TO 600 Alii' RATING) 28-SERIES COIL( USED WITH INDUCTIVE SERIES COIU 29--INSULATING TUBE 30--INSULATING TUBE 31 -NUT

(200 T0600 AMPS.)

1200 AMP BREAKER PANEL ASSEMBLY APRIL 13,1955 71-540-038

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I···MOVASLE ARCING CON TACT 2···MOVABLE MAIN CONTACT 3·· ·STATIONARY ARCING CONTACT a ARC RUNNER +··FRAME 5-· SCREW &-··SCREW

7··· STATIONARY MAIN CONTACT BLOCK &···SCREW 9 ·· · STUD CONNECTORS

IO · ··MAIN CONTACT SPRINGS I I ···MAIN CONTACT FINGER 12 ···SHIE LD

1600 APRIL 14,1955

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I I I

O! 13·-tiiNGE CONTACT SPRINGS 14-·SCREW 15···HINGE CONTACT BLOCK 16--tiiNGE CONTACT FINGER 17-··RETAIIING RING a H INGE P IN 18--MAIII OPERATING SH AFT 19 --(;()IITACT OPERATING LEVER

2D--ARCING CON"IIICT SPRING 21-·ARCING CONTACT INSULATION

22- SPRING WASHER 23·-RETAINING WASHER 25-· ·NUT

AMPERE

FIG.2B BREAKER PANEL

28·-SERIES C OILIUSED WITH INDUCTIVE SERIES COIL) 51-SCREW 32-·SCREW 33···TUBE 34-IIRIDGE

ASSEMBLY 71-540·037

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-UAL CLOSM-( 10 L£Y£II

FIG-3 CLOSE POSITION

II

FIG-4 t}, TRIP FREE POSITION

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:i, 1":'\_� y {i��=..rACT ... .!..< ,-...._ 'i'--STATIONAIIY � .� .... COIITACT i-;l'

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c�� .FIXED CEIITER o---E CEIITER (Q}-CMI-.L e--FIXED TOMEJIIIER

-CLOS£-(12 CAlli

l SCHEMATIC DIAGRA M OF

TYPE 'LA' OPE RATING MECHAN ISM

FIG-5 OPE N POSITION

MARCH I, 1955 71-540-025

. 10 TR1�

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ALLIS·CHALMERS � MAIUFACTURIIG COMPAIY

7 TYPICAL WIRING DIAGRAM FOR

HYDRAU LICALLY OPERATED BREAKER S

FIG. 6

A.C.B.

-+---t--7.....--INDUCTIVE SERIES COILS

4 15 II 12 I! 14 115

1111111 arsro�ar�ar'i 9 10 16 17 18 19 20

SERIES TRIP COILS

800 AMPS a ABOV E 600 AMPS a BELOW

TYPICAL WIRING DIAGRAM FOR MANUALLY OPERATED BREAKER S

FIG. 6 A MARCH I, 1955 71-340-077

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·. . ·�, '' -�f;� . .. i' :> .J!Itj., �. ' ... _:; INSTRUCT IONS

FOR THE INSTALLATION AND OPERATION OF

ALLIS-CHALMERS TYPE LA-50 LOW VOLTAGE AIR CIRCUIT BREAKER

AND AUXILIARY EQUIPMENT

PART I GENERAL INFORMATION

A. Introduction. The type LA-50 air circuit breaker is one of a line of low voltage air breakers which may be used · in metal enclosed switchgear, on open type switchboards, or separately mounted in individual housings. The LA-50 breaker seri"es is composed of two �pere classes, the 1200 ampere class for continuous current ranges of 200 to 1200 amperes, and the 1600 ampere class. The Ll-50 air circuit breaker has an interr­upting capacity of 50,000 amperes and a ma�mum continuous current rating of 1600 amperes at 600 volts, 60 eycles. For information on other frequencies, the factory should be . consulted, All LK-50 breakers are completely·assembled, tested , and calibrated at the factory in a vertical position and must be so installed to operate properly. Customers primary connec­tions should be adequately braced against the effects of short circuit currents to prevent overstressing the breaker terminals .

B, Warranty . Allis-Chalmers LA-50 air circuit breakers are warranted to be l'ree of defects in material and workmanship for a period of one year after delivery to the--original purchaser.

·This warranty is limited to the furnishing _ o£ any part which·t,o our :aatisfaction has been proven defective�- Allis•Chalth,rs ·will not in any case aesume responsibility for allied equipment of''' any kind.

C, Receiving and Inspection for Damage Eacl:l LA.-50. a ir circuit breaker and ite associated apparatus !s carefully ··· checked, inspected, and packed at the factory by·workman ex­perienced in the proper handling of electrical equipment. Immediately upon receipt of this equipment , carefully remove �11 packing traces and examine parts, checking them againet the

·

pack :tng list and carefully noting any damages incurred in tra�sit. ·If such is die closed a damage claim should be filed at once with the transpor tation compa ny and Allis-Chalmers notified. Keep instruction books and tags with the breakers.

D, Storage . When breakers are not to be put into lmmediati use, they should be carefully wrapped or covered to provide protection from plaster or concrete dust and other foreign matter. Abrasive dust in the breaker can causa ex-

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ALli,S·CHALMERS � MAIIUFACTURIIIG ·cOMPANY

Figure

1

2

2a

2b

3 4 5

6

7

8

9

10

11

12

13

14

15

16

16a

17

18

BWX-6427

LIST OF ILLUSTRATIONS COVERING ALLIS-CHALMERS TYPE LA-50

LOW VOLTAGE AIR CIRCUIT BREAKER AND AUXILIARY EQUIPMENT

Description

Hydraulically Operat ed Breaker

Manually Operated Breaker

1200 Amp Contact Structure

1600 Amp Contact Structure

Operating Mechanism (Schematic)

Wiring Diagrams

Auxil��ry Switch

S econdary llisconnect

Hydraulic Operator Assembly

L imit Switch

Shunt Trip Device

Series Trip Device

Thermal Trip ·'Device

Indicator Flag, Mechanical Lockout, .B ell Alarm Switch, and Reset Button for Overcurrent Trip Device s .

Series Trip Curves (Dual Magnetic)

Series Trip Curves (Dual S elective)

T.ime Curves·of Series Trip Elements (S.T., Lt . & Inst .)

Thermal Trip Curves

Undervoltage Trip Device

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ALLIS·CHALMERS � MAIIUFACTURIIIG COMPANY

CONTENTS

. INDEX TO INSTRUCTION BOOK COVERING

TYPE LA-50 AIR CIRCUIT BREAKER

Part I. General Information

A. Introduction B. Warranty C. Receiving and Inspection for Damage D. Storage

Part II. Installation and Operation

PAGE NO.

1 1 1 1

A. Mounting 2 B. Inspection 2 C. Operating Mechanism Check 3 D. Trip Units and Accessory Devices 3 E. Pantograph and Trip Interlock Adjustment J F . Energizing the Breaker 4

Part III. Description and Function of Parts

A. Operating Mechanism B. Contacts C. Method of Arc Interruption D. Relays E. Trip Units and Accessory Devices

Part IV. Maintenance, Ad.iustment and Replacement

A,. General B� Periodic Inspection C. Maintenance Check List D. Movable Arcing Contact E. Stationary Arcing Contact F. Movable Main Contact G. S tationary Main Contacts H. Trip Units and Accessory Devices I. Operating Mechanism (Manual) J. Operating Mechanism (Hydraulic)

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7 7 7

10 10 10 10 11 11 11

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Observe that the manual operating handle (2-17 ) � returns from closed �o neutral positions automatically by

action of its return spring ( 2 -14 ) .

Next open breaker by means of manual trip button (2-1) on front of breaker. The toggle linkage (2-37) will collapse, the contacts will move to the open position freely and rapidly, and the closing mechanism will reset, ready for the next operation. Operating springs ( 2 -4) assist in rapid opening of the contacts and actuate the resetting of the closing. mechanism.

C. Operating Mechanism Check. The operating mechanism is properly adjusted and tested at the factory, and ordinarily there should be no need for readjustment in the field. If for -some reason, the mechanism fails to latch in the closed po�ition, check to be certain that all trip devices are reset and not interfering with the trip latch (2-31 ) . The trip latch should be free to return to its latching position; If the trip latch is free and the mechanism still fails to latch, check to be certain that there are no binds or interferences in the mechanism and that all links and latches are fully reset. If breaker is still unstable, the trip latch reset spring (2-30) may be adjusted to increase its reaction against the latch (refer to Maintanance Check List, Part IV, Section C). However, before changing any adjustments be certain that the trip latch engage­ment is sufficient, as ou�lined in the maintenance check list.

D. Trip Units and Accessory Devices. These items also should receive a thorough check prior to placing breaker in service to be certain that adjustments are proper and parts are not damaged. Refer to Parts V and VI of the instruction book for the description of adjustments and functions of these devices.

E. Pantograph and Trip Interlock Adjustment. This applies only to cubicle mounted breakers of the drawout type. As a closed breaker is racked into position it should trip shortly after it passes the "test position" indicator; At t�a poi�t. the control circuits will be made, but the primary con­nections will be open, and it will be impossible to close the breaker until it reaches the "operating position" indicator. Continue racking breaker in a nd close it when the operating position is reached. Closing should not be affected by the interlock mechanism. The�, as the closed breaker is racked out towards the test position, after approximately·5/16 inches travel the breaker should trip. At this point, disconnect fingers (1-14) will still be in full contact with the stationary stud, and it will be impossible to close the breaker again until the test position is reached. If the mechanism does not �unction as described, refer to the cubicle instruction book for correc­tive �djustments.

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the Y contacts close th e X re la y an d hydrauli c pump moto r a r e d e e nergi zed , but the Y relay will remain energi z ed as long a s the control s wi tch is held clos e d .· Thi e pr events "pumping" or r e pe ated a tte mpts to clos e . The contr ol s witch must b e opened b e fore anoth er closing attempt i s pos s ible . The hy�raulic pump m o tor and the X relay coil ar e de s igned for inte rmittent duty and mus t no t be p e rmitted to r emai n e nergi z ed any long e r than i s ne ce s sa ry to clos e the breake r . The XY relay s ch eme a ccompli she s thi s automa ticall,y. Fig . (6) shows a "tfypic�l. wiring d iagram. Although va r.ia tions may be ne ces sary�· or o ther control e lements add e d, to suit a spe cifi c applicati on, �be ba s i c XY relay arra,pge men t will usually be aa de scribed.·

E. Tri p Uni ts and Access ory p�va,c·es • . J)eecription and functi on o f" the se itep}s· are covered in Parts ·V and VI of th e ins truction b ook.

PART IV MA INTENA NCE,,, ADJUSTMENT, AND REPLAC_EMENT

A . Gene ral . Occas ional che cking and c.l,eaning of the breake r wil l promo te long and troublefree servi ce . Oiling and greas ing should b e done wi th care b e caus e e xce s s o il and.gr e as e tend to colle ct d i rt wh i ch i h time might make operation aluggish and aff e ct the di el e ctri c strength of insulating membe rs. Always re fe r to the ins tructi on book b efore r e moving parts or chang ing adj us tments . A re ch eck of the ins tallati on insp ectfon (Part II) dur ing maintenance will indi ca te the overa ll ge neral cond:J.tion of the breaker.

B. Periodic Ins pe ction. A pe riod i c inspe ctio n;and s ervi cing should be included in the bre aker mainte nan ce routine. A s emi-annual inspe ction i s usua lly s ufficient, however, in cas e s wh�re unfa vorable atmospheri c condi tions e xi s t, more frequent inspecti ons ar e �e commended. In any case , th� total number of breaker ope ra tions b e tween s e rvi cing should not e xceed 500 for the LA-50 breaker . Th e ma intenance ch e ck l i st {Se ction C) will provide a ready and convenient guide to a thorough and unders tanding inspe ction of the b reak er. Servicing will be facili ta te d if a tag i s a tta ched to e ach uni t l is ting dat e , operation counter reading, ·da te o f ne xt ins pe ction , counter rea ding at next inspe ction, and s er vi ce man's s i gnature • .

C. Maintenance Che ck Lis t. The following items are l i s te d f or conveni ence in maintaining the e quipment in the beat pos s ible condi ti on. By pe riodi ca �ly che ck ing and mainta,in ing these items , th e bre ak er s will provide the continu�d satisfactory servi ce of whi ch th ey are capable . _ ·

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H . Tri p Un its and Acc e s sory D evic es . For ma int enance, adjustment, and replacem e nt of these devices refer to Parts V and VI of the i nstruction book , where detailed instructi ons will be found .

I . Operating Mechan i s m (Manual ) . Th e manually operated m echan i sm is fastened to the breaker pan el frame by eight screws ( 2-21 ) . Shims ( 2 -2 2 ) are used to adjust ma in contacts ( see · section IV- C -5 ) and must not be changed for any other r eason . The operator may b e remov ed from the breaker by disconne cting break er operating link ( 2- 3 9 ) and remov ing four screws ( 2 -21 ) , carefully noting amount of shims (2-22 ) . After reassembly, pay particular att ention to trip latch adjustments and main c ontact adjustme nts to be c ertai n th ey have not changed. Ch eck me cha­n i sms for ease of operation and freedom from binds .

J . Operating Mechanism ( Hydraulic ) . Th e hydraulic operating m echanism is exactly the same as the manual me chanism, with the addition of hydraulic cylinder and accessories to . ac complish the closing operation . The manual closing means i s r etained, as in the manually ope rated breaker. The operating mechanism and hydr.aulic mechani s m can be removed as a unit as described in Section IV - I, after disconnecting the clQsing mot or and limit switch leads . Should the hydraulic mechanism b e remov ed from the operati ng mech an i sm, it must b e carefully readjusted on as s embly a s outlin ed in Section IV - C-12 . A D. C. motor is furnish ed for us e with a direct cur rent source. Whe n th e breake r is to be- - operated from an alternating current sotirce, an A. C. motor i s furnished . Thus, rect ifiers and aging resis tors are not requir ed .

PART V PROTECT IVE DEVICES

A. Seri e s Overcurrent Trip D evice A s s embly Adj ustme nt and C alibration . S er i e s overcurrent trip d e vices used on low voltage breakers function to trfp the breaker wh enever the current through the breake r exceeds a predetermin ed value . This device includes a series coil, magnetic circuit with two arm­atures, and a sealed oil t im e delay device . This arrangement is varied somewhat on current · rat_ings above 600 amps . on the LA-50 , and the LA-75 breakers, in that th e tri p dev ic e coil is not tied to th e low er contact structure, but is link ed to an inductive series coil mounted on th e fixed bus in the rear of th e breaker . Figur e 12 shows the arrangement of the functional components of this device and F�gure s 15 , 16 give the inve rse time delay character� stics .

The trip elements available i n the vari'ous categories of series trip device s ar e thre e in number and calibrated in th e following ranges .

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condition exists in t he series coil ( 13 - 12 ) , it causes a s imilar overcurrent in the secondary coil ( 13-9 ) due to the transformer a ct ion in the fixed a rmatur e ( 13-16 ) . This overcurrent condit ion in the secondary coi l gen erates heat t o the spiral wound. bi­metallic elem e nt ( 13-3 ) by me ans of t h e nichrome w i re h e at e r c oil ( 13 -2 ) wh ich surrounds t his element. The heat generat ed in the h eater coil ( 1 3 -2 ) causes the free end of the . bimetallic element ( 13-3 ) to rotate along with cam ( 13 - 5 ) wh ich is fast ened to it. On overloads , th e rotation of cam ( 13 - 5 ) is suffi c i ent to release t h e th ermal trip armatur e ( 13 -19 ) which was previous+y restrain ed by roller ( 13 - 7 ) working against this cam . Upon being released , the the rmal armature rotates on shaft ( 13 -10 ) s o as. to close the air gap through which it is ele·ctromagnet i­cally attracted to the core assembly ( 13 -13 ) . As the the rmal a rma tur e ( 13 -19 ) closes this gap it picks up and engages t h e trip block ( 2 -34 ) at trip s crew { 13 - 14 ) and acts to trip t h e breaker as pr eviously des cribed in S e ct ion III · - A of the operating me chanism . The break er having tripped , the c ore assembly ( 13 -13 ) is no longer energi z ed which allows the thermal

· i arm�ture to b e returned t o its lat ched pos ition by return spring ( 13 -18 ) . A short t ime int erval may be required to complet ely res et cam ( 13 - 5 ) aft er trip cycle is complet ed due to cpoling of bime tallic element .

Be caus e of the inherent long t ime delay of thi s d evi ce it i s equipped with an instantaneous trip armature ( 13 -21 ) which provides high-overload prot ection. This inst�ntaneous t rip armature is fa ct ory set so as to trip the breaker whenever there is an overload of 8 to 12 times normal coil current .

Trip screw { 13 -14 ) on thermal trip armature ( 13 - 1 9 ) is removed for thos e applicati ons whi ch require the thermal armature to s ound a bell alarm on overcurrent condit ions , ·but not trip the breaker . Under these condit ions the instantaneous trip armature ( 13-21 ) must have the trip s crew ( 13 - 14 ) properly adjust ed f or h igh ov erload protection . For detail s c onc erning reset of t h e bell alarm see Se ction VI - . C under bell alarm .

INSPECTION AND ADJUSTMENT

The thermal magnetic trip device should be inspe ct e d prior to b e ing put in s ervi ce in th e same manner as th e s eries tri p devi c e t o c he ck that the pickup calibration is in ac cordance with the appl i c at ion requirements . The th ermal trip devi c e leaves the factory with the fol l owing standard s ettings unless otherwis e sp e c i fi ed in the purchase order :

Th ermal magne t i c trip element i e s et at lOo% Bickup calibrat ion . In stantan eous trip element is s et at 800% pi c kup . T h e th ermal magneti c t rip e l ement may be adjusted without furth er t e s t ing a s t h i s e lement ha s b e e n fa cto ry cal ibrat ed over it s full range , but th e instantaneous e l ement would requir e calibra­ti on t o chang e it s pickup value . T o ad j u s t instantan eous pi c kup ,

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moved and that the armature { 18-13 ) slides freely to the breaker trip position without being energized . This device (with t ime delay ) leaves the factory set at 2 seconds time delay , when the voltage drops to z ero , unless oth erwi�e specifi ed . The t ime delay device is adjustable , but not ca librated , between 2 ;5 s econds and . 5 s econds . This adjustment i s obtained by loosen­ing nut (18-10 ) and posit ioning t ime delay device { 18-o ) on bell crank (18- 5 ) as shown in l Fig . 9 ) . The pick up and drop settings can b e adjusted by loosening locknut { 18-11 ) and adjust­ing the pre-compres sion of springs (18-3 ) and ( 18-4 ) . by turning adjusting nut (18-12 ) .

NOTE : After making this adjustme nt , a __ check should be made to see that the armature still seats firmly on the pole head, otherwise the increased exciting current may ·�ause ·the coil to overheat. � ·

June 195 5

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Allis-Chalmers Mfg . Company Boston Works Boston , Mass·.

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.. ALLIS·CHALMERS � MAIIU FACTURI II G COMPANY

l 11ANUA1. TIIIP a R£S(T IIVTTON 15. CAM FOLLOWER lt SCREW

t. PROP LATaf SPRING ML OPERATIONS COUNTER (WH(N REQUIRED) Zl OVERCURRENT TRIP OEVICI 1 PROP LATCH R IU.NIJAI. CLOSING HANOL! u. TRIP LATCH AOJUSTINO SCREW a MANUAl. TIIIP 4. OPENING SPRING .. OPEN-Gt.OS£ INDICATOR LATCH AO-IUSTING SPRINI I ACTUATED IY 0 I 5. LATCH PIN 19. OPERATING WECHAHr5N fRAME 3Q TRIP LATCH ADJVSTWG SPRING

.. foWH CLOSING UNK 20. INDICATOR LINK 31. TRIP UJCH T UFT PIN 2l SCREW 32. PRIMARY TRIP LEVER

� YOI<[ 22. �TACT AOJUSTlHG SHIW 33. IIANUAL TRIP a RESET SPRINI

.. l.OCICIHO SCREW 23. FRONT BARRIER 34. TRIP Bl.OCX 10. IREAK[R �OCK LATCH 24. PHASE BARRIER n IIAHUAL TRIP BLOCK

II. IIAHUAL CLOSING CAll OV£IITIIAV£l. STOI' P11 25. ARC CHUTE 36. st:CONOARY TRIP LEVER

12. MANUAL CLOSINO CAM 211. PANEL ASSENBLY 3T IIAIN TOGGLE liNK

11 lJHK IZOO ANf PANEl SEE FIG Za 38. ROCICIHG LINK

14. CLOSING HANDLE RETURN SPRING 20.00 ANf PllNEL SEE FIG 2b )9 CONTACT OPERATING Lf:VER

40. CAM FOLLOWER

F I G 2 MANUALLY O P ERATED BRE AKER APRIL 5 , 19, www .

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ALLIS·CHALMERS � MANU FACTURI N G COMPA NY

9 II A. STATIONARY CONTACT I I 8 OVABLE CONTACT I '

F IG. IO LIMIT SWITCH

CLOSED POSITION FEB. 1 1, 1955 71- 240-136

FIG. I I SHUNT T R I P D E V I C E

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ALLIS·CHALMERS � MAIIUFACT URI II G COMPA NY

AUXILIARY SWITCH FIG. 7

SECONDARY DISCONNECT ASSEMBLY FIG .8 www .

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IIWCUOL CLOS ... -{ 10 LEVEll

FIG-3 C LO S E POSITION

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.FIXED CEIITER o--lE CIEIITIEIO

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l SCHEMATIC DIAGRAM OF

T Y P E •LA• OPERATI NG MECHANISM

FIG-5 OPEN POSITION

MARCH I, 1955 71- 540-025

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I ---MOVABLE ARCING CONTACT 2--MOVABLE MAIN CONTACT

3--- STATIONARY ARCING CONTACT 8 ARC RUNNER

4---FRAME

5--- SCREW 6 · · -SCREW 7--- STATIONARY MAIN CONTACT BLOCK

8---SCREW 9--- LOWER STUD CONNECTOR

1 0-··MAIN CONTACT SPftiNGS 1 1 ··-MAIN CONTACT FINGER

1 2·-- SHIELO

13--HINGE CONTACT SPRINGS 14-·· SCREW 15-·-HINGE CONTACT BLOCK 1 6---HINGE CONTACT FINGER

17··-RETAINING RING 8 HI NGE PIN 1 8··-MAIN OPERATING SHAFT 1 9··-GONTACT OPERATING LEVER

2o--ARCING CONTACT SPRING 21·--ARCING CONTACT INSULATION

22-SPRING WASHER 23--RETAINING WASHER 24-··SCREW

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SECTION A -A

.IIHIPDI �ltlfNT ( 100 TO 1200 AMPS)

F I G. 2 A

25-·-5CREW 2&---.IUMPER f!T- SERIES COIL (COILS 200 TO 600 AMP RATING) 28-SERIES COIL( USED WITH· INDUCTIVE SERIES COIU

29--INSUI..ATING TU8E :50--INSULATING TUBE

:SI-NUT

( 200 T0600 AMPS.)

1200 AMP BREAKER PANEL ASSEMBLY APRIL 1 3, 1 95!5 7HHO -D36

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AUXILIARY-..(� SWITCH

LIMIT S W I TCH

'v"REL.lY--

INTERLOCK--( I TRIP BAR

VIEW SHOWING R E LAY MOUNTING

( LEFT HAND V IEW)

1----- !8 ff------1 INOICATING LIGHTS --(13 a PtJSH BUTTON

-(SPARE) AUXILIARY

SWITCH

10 )--UNOERVOLT.lGE TRIP

PROVISION--( I I FllR PADLOCK w '"i� ' u-u 'Lif�l -@-- HYDRAULIC CLOSING I I � DEVICE - MOTOR a PUMP ASSEMBLY

8)-- MOTDII NAMEPLATE

- HYDRAULIC CLOSING DEVICE - 0 YLINOEII

. .,_._. FIG-I H Y DRAULICALLY OPERATED

BREAKER 2 -28-55 71- 540-024

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contact swit ch i s u s e d t o i nt errupt it s c ircui t immediat e ly a ft e r t h e b r ea k e r i s t r i pp e d . Ea ch e l ectr ically operated b r ea k e r i s equ i p p e d w it h a shun t t r ipp ing de vice for rem ote c o nt r ol . T h i s d e v i c e i s mount e d o n a bracket on the l eft sid e o f t h e me c h an i sm frame a s

_s h own on Fig. l . I t i n c lu d e s a co i l,

magn e t , armat u r e and r e t urn to rsion s prings. Energi zation of th e coil ( l l- 3 ) cau s e s a rmatur e ( ll - 2 ) to p ickup and engage trip bar ( l l - 4 ) t h e reby t r ip p i ng t h e breake r. The tors i on s prings ( ll -1 ) a r e u s e d p r ima r i ly t o r eturn the armatur e t o a ne utral position aft er the breake r tri p s. Little or no mainte­nance or adj us tme nt is required on this d evice. To ch eck, move the armature to t he pickup posit ion and note that the trip bar has mov ed the trip latch as explained in S ection III Paragraph A under operating me chanism.

B. Auxiliary Switch Attachm ent. The auxiliary switch F igure 7 is of the rotary type and i s sturdily constructed. Thi s switch i s mounted on th e operating mechanism frame and functi ons by dir ect connection to th e breaker mechani sm. Elec­trically ope rated breakers are provided with 2 "a" and 2 " b" ( 7-4 ) contacts in thi s switch, mounted on the l eft s ide of th e m echanism. Pro v isions are available for th e mount ing of an id enti cal switch on t he rever s e sid e. "a" switche s are cl o s ed when the breaker contact s a r e clos ed, and "b" switches clos ed when breaker contacts are op en. Th e auxiliary switch contacts ar e factory s et for "a" and " b" pos it ion, but may be int er­changed in th e f i e ld by reas s embling the rotor e l ement ( 7-1 ) as d esired. A mould ed bakelite c o v e r l 7-3 ) which s naps on can . be easily removed for contact ins pection.

c . Bell Alarm Switch Attachme nt. The bell alarm switch ( 14-8 ) functi ons to cl ose an alarm circuit upon aut omatic ov ercurrent tripping of the breaker, or by s pecial application may indic�te an overcurrent condit ion by s ound ing an alarm wi�h­out t ripping t h e breaker. This switch i s a s ingl e pole double throw switch mount e d on t h e outer pha s e tr ip d e vic e. The b e ll alarm switch i s actuated by lockout l ever ( 14-9 ) which -rotat e s with re s et shaft ( 14 - l ) . Th e rotat i on o f the re s et shaft is d e scrib ed und er " s eri e s trip flag indication" Section V Para­graph C. The rotation of lockout l ever ( 14-9 ) trips toggle s pring ( 14-16 ) which holds this lever in th e tripped posit i on until re s et button ( 14-6 ) i s actuated to r e s et the res et shaft. It must be noted that the bell alarm switch i s r e s et only by manually actuating the r e s e t button ( 14-6 ) . Re placement of the b el l alarm switch requires only th e removal o f two mount ing screws holding switch to the trip device. On reass embly c heck to be certai n that alarm w ill . s ound when lockout l ever ( 14-9 ) i s re l eas ed o

D . Mechanical Overcurrent Lockout Attachment. The mechan ical lockout f eatur e prevents t h e circuit breaker from being clos ed e ither manually or electrically after being tr ipped

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plung e r var i es t h e f or c e app l i ed t o th e t ime d e lay d e vi c e b y changi ng th e l ever a rm an d a l s o c han g i ng th e strok e requ i r e d for t r i pping . Ea ch t ime b and , maximum , i nt e rmediat e o r m i n imum , i s ma rke d by a whi t e band in d i cat i ng t h e m ount ing po int f o r t h e t im e delay d e v i c e p lunge r . All o f t h e band l o cat ions a r e p r o gre s s ive and i f d e s i red , int ermed iat e s et t i ngs may b e ma d e b e tween th e cal i b rat ed point s fo r fin er s e l e ct ivity .

Th e pi c kup c al i brat i on o f th e a rmat ur e s i s s ele c t e d by r ot at ing kn ob ( 12 -2 ) wh i ch mov e s t h e cal ibrat i on lab e l ( 12-3 ) t o the r e quir ed s et t ing . A d j ustme nt of the calib rat i on labe l i n c r e a s e s o r d e crea s e s t e ns i on i n t h e p i c kup spring and i s fact ory calibrat ed for valu e s of pi ckup curr e nt .

I NSPECTION AND ADJUSTMENT

Th e s e ri e s t r i p d e v i c e sh ould b e i nspe ct ed pri o r t o b e i ng put in s ervi c e t o s e e that t h e pi ckup calibrat i on and t ime delay band s e l e ct i ons are in a c c or danc e with t h e appl i ca­t i on requirement s . This dev i c e l eave s t h e fa ct ory with t h e fol lowing standard s e ttings unl e s s oth erwis e s p e c i f i ed i n th e ·purch a s e ord er � Long t ime de lay el ement i s s et at 100% ·p i ckup on t h e int ermediat e t ime d elay band n S hort t im e delay e l em e nt i s s et at 750% pi ckup on th e int e rmediat e t ime d elay band . Instantaneous t r i p e lement - i s s et at BOO% pi ckup . S e l e ct i on s ot h e r than tho s e already mad e t o t h e d e v i c e d o not re qui r e fur ther t es t i ng in t hat t h e unit i s c om plet e ly calibrat e d a t t h e fa c t o ry . Th e curr ent rat ing of th e s e rie s coil i s st amp e d on t he breaker Name plate s and s houl d b e che c k ed in appl i c at i on s i nvolving var i ed cur r e nt rat ings .

MAI NTENANCE AND REPLACEMENT

The i nd i v i dual pha s e s e rie s t ri p devi c e a s s embl i es are mount ed on a c ommon ba s e and mus t b e r emove d from th e breaker for mai nt ena nc e or r e pla c ement a s one a s s embly . T o remove t h i s a s s e mbly , det a ch t h e a s s embly mount ing b ol t s ( 2 -27 1 and s c rews ( 2a-24 ) h olding the s e ri e s o ve r current c oi l s ( 12 -7 ) t o t h e cont a ct s t ructure . NOTE : ON THOSE APPLICATIONS ABOVE 600 AMPERE COIL RAT ING , . THE OVERCURRENT COILS ARE LINKED TO INDUCTIVE S ERIES COILS MOUNTED IN THE .REAR OF· T HE BREAKER , AND: THESE COIL LEADS MUS T BE DISCONNECTED TO REMOvE THIS ASSEMBLY . Having removed the a s s embly fr om · t h e breaker ea ch single pha s e ass embly ca n t h e n b e detached from the c ommon ba s e by the removal of four mount ing s c rews { 14-15 ) and t h e res et shaft ( l4-� .

T o remove s e r i e s coil ( 12 -7 ) whi ch d oe s not requir e a s in gl e pha s e di s a a a embly1 det a ch th e four mount i ng s cre�s ( 12 - 5 ) hold i ng c ore a s s embly ( lG - 8 ) in - pla ce a nd sl i de the c ompl e t e c o re a s s embly out of t h e d e vi c e . The s e r i e s c oil wi ll th en s l id e o ff t h e c o re l e g and c a n b e a s s embl e d i n the r evers e st e p s .

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p o s it i oning slott ed end of s pr ing ( 2-30 ) - c l o ckwi se t o decreas e t ri pping forc e , and count erclockwis e t o increa s e the tripping forc e .

Trip lat ch ( 2 -31 ) engagement on s e condary trip l e ver ( 2 -36 ) roll should be 1/8" to 3/16 " . Mea sureme nt is from th e l eading edge of trip lat ch fa ce t o - the line of cont a ct on th e lat ch fac e . Adjustment is obtained by the po s it i oning of a fixed stop in th e me chanism frame .

8 . Trip lat ch r oll adjustment . Trip lat ch r oll on s c rew ( 2 -29 ) should have 1/32" t o 1/64" clearan c e t o t rip block ( 2-34 ) with t he t rip block aga inst its a t op . Adjustment i s o btained by pos itioning screw ( 2 -2 9 ) ;

9 . R e set button . The r e s et butt on ( 14-6 ) i s a d j ust e d t o provide 1/16" t o 1/8" c l earan c e b etwe en r e s et lever ( 14-10 ) on the break er and t ri p devic e r e s et l e ver ( 14-17 ) w it h t h e res et shaft ( 14-1 ) o n t h e t rip devi c e i n t h e t ri pped pos it i on .

10 . Operat i on count er . The operat i on c ount er ( 2 - 16 ) wh en suppli ed is actuat ed by the open-clos e indi cat or ( 2 -18 ) and i s adjus t e d such that the count er arm ha s s ome overtravel when break er is ope n .

11 . Limit 3Wit ch . With break e r in clo sed and lat ch ed p o s it ion , the uppe r c onta·e·t s ( 10-8 ) ( 10-9 ) o f l imit swit ch ( 10-3 ) should have 1/32" follow-up aft er contact make . Adjustment � s by us e o f shims ( 10-7 ) between swit ch and mounting pad .

12 . Hydrauli c operat or a s s embly . The hydrauli c operat or a s s embly ( Fi g . 9 ) i s mount ed on the operat ing me chanism frame ( 2 -19 ) and held in posit i on by mount ing s crews l 9-4 ) . Energi zat ion of the mot or ( 9-8 ) caus e � pump l 9-14) to move hydraul ic fluid from the res ervoir ( 9-13 ) through the pump and c onnect ing tabl e ( 9-16 ) int o cylinder ( 9-2 ) under pre s sure . Thi s hydrauli c fluid under pressure move s plunger l 9-3 ) up a gainst clos ing cam ram pin ( 9- 9 ) whi ch in turn clos e s . th e break e r . The vert i cal mot i on of . the plung er c ompre s s e s plunger r eturn spri ng ( 9-15 ) whi ch returns the fluid back through th e c onne ct ing tub e into the res ervo i r .

Should readjustme nt be n e c e ssary , t h e f ollowi ng pro c e dure �h ould be us ed . With th e breaker in the closed pos iti on , rot at e clos ing handl e t o t ak e up all fre e mot i on in h andle , a clearanc e of 1-1/16" to 1-3/3 2 " .shoUld · be maint.ained · b etwee n the e nd of plunger ( 9-3 ) a nd c onta ct surfa cp of clos ing c am ram pin ( 9- 9 ) . R emove or add shim ( 9- 5 ) t o maintain this adjustment . Aft er this adjustment has b ee n . made , there sh ould be a minimum of 1/64" clearance b etwe en main c l o s ing cam ( 9- l ) and clo sing cam overtrave l st op ( 9-lO ) ( Fig . 9 dimension "A" ). With t h e breaker in the open pos i t i on th e re sh ould be a minimum

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Thus link ( 1 5 ) will move t o the l e ft and open the breaker contact s ( 3 ) and ( 4 ) . When the me chan ism rea che s the open posit ion , link ( l3 ) · is relea s ed from link ( 19 ) and the me cha­nism is reset by spring ( 20 ) to the open posit ion as shown in Fig . 5.

Fig . 4 shows the me chanism in the trip-free posit ion . S ince lat ch ( 5 ) and levers ( 6 ) and ( 7 ) are released , cent er ( D1 i s not temporarily held as in - a normal clos ing ope ration . Thus wh en link ( 13 ) rotat es c ount erclockwi s e , spr ing react ion holds c ent er ( 2 3 ) fixed and link ( 14 ) rotat es c ount erclockwise about c enter ( 23 ) . Thus , although link { 13 ) goes through it s c omplet e strok e , link ( 1 5 ) doe s not move and the breaker contac t s will not clos e . Thi s action can take place during any part of the c losing stroke , caus ing contac t s t o imme diat ely return t o the open position even though the hydrauli c operat or r emains energi zed or the manual closing s troke is c omplet ed .

B . Contact s . Th e contact structure for the 1200 ampere cla s s LA- 50 is shown in Fig . 2a . The contact structure for th e 1600 ampere class LA- 50 is shown in Fig . 2b . The 1600 ampere cla s s contact structure is the same as the 1200 ampere class conta ct structure exc e pt for the addit ion . of an extra pair of primary d i sconn e ct contacts and addit ional conduct or mat erial in the cont a ct structure .

The c ontact s on the LA- 5 0 breaker consist of main c urrent carrying contact s and arc ing c onta ct s . Th ey are arranged such that contact make and break is by means of t h e arc ing contact s , while t h e ma in c ontacts a r e not subj e ct ed t o arc ing . Arcing contact surface s are c lad with a silver tungst en arc ing alloy wh ich greatly redu c e s me chani cal wear and arc erosion . Th e positive wiping act i on of the arc ing c ontact s , as well as the properties of t h e contact mat erial , prevents weld­ing and sti cking when int errupt ing h i gh current s . Thi s insures long sat i sfact ory s e rvic e .

Another feature of the contact structure i s the "blow­on" effe ct produced by the phys i cal configurat ion of t h e moving member . This i s best shown s ch emati cally as in Fig . 5 . The current path , when main c ontact s only are part ed , is from the arcing contact { 5-3 ) to pivot point ( I) , and t hence complet ely around the loop of the main contact t o pivot point { F ) . The me chanical for c e s produced by current flowing in such - a path t end t o hold the arcing c onta ct s solidly in cont a ct·, both in opening and in closing , and thereby prevent premature or un­c ontrolled contact parting or b oun c e . Both the stati onary and th e movable arc ing contact s have arc runners whi ch l ead the arc away from the c onta ct surfa c e s . Th is prolongs c ontact life as well as aiding arc int errupt i on .

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t e Installation, Care and Operation of Circuit Breakers and Accessories

TYPE LA-50 AIR CIRCUIT BREAKER

BOO� BWX-6427

The s e instructions are n o t intended t o cover all deta� l s or variati ons that may be enc ountered in connection with the - in s t al l ation , o peration, and maintenance of this equipmen t . Should additional information b e de sired contact the Al l i s -Chalmers Mfg . Company .

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ALLIS·CH ALMER S � MAII UFACTURI IIG COMPANY

CONTENTS ( CONT 1 n)

Part v . A .

B .

c .

Part VI .

A . B . c . D . E .

BWX-6427

Prot ective Devi ces

Series Overcurrent Trip Devi ce Assembly Adjustment and Calibration

Inspection and Adjustment Maintenance and Replac ement

Thermal Magnetic Overcurrent Trip Device Assembly

Inspe ction and Adjustment Maintenance and Replacement

Overcurrent Trip Flag Indicator and Reset

Accesso� Attachments

Shunt Trip Attachment , Auxiliary Swit ch Attachment Bell Alarm Switch Attachment Mechani cal Overcurrent Lockout Undervoltage Trip Device

Inspection and Adjustment - .

' "'

Attachment

PAGE NO .

11 13 13

14 15 16 16

16 . 17

17 17 18 1 8

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' ., . . A:L:LIS·CHiLMERS � ;-M-AIUFACTURiiiG COMP4NY

CAUT IONS TO BE OBSERVED IN THE INSTALLATION AND OPERATION OF. THE LA-50 AIR CIRCUIT BREAKER

1 . DO NOT ATTEMPT TO OPERATE BREAKER OR INSERT IN CU

-BICLE UNTIL ALL PACKI NG TRACES HAVE BEEN REMOVED .

. . . .

2 . READ INSTRUCTION BOOK BEFORE MAKING ANY CHANGES- OR ADJUSTMEN�S ON THE BREAKER . ·

3 . DO NOT 'INTERCHANGE PARTS OF TRIP DEVICES ... TO DO so­MAY CHANGE CALIBRATIONS .

- 4 . ALWAYS OPERATE MANUAL CLOSING HANDLE QUICKtY AND DECISIVELY - TO HES ITATE IN MID-STROKE _MAY CAUSE -UNDUE BURNING OF CONTACTS . _

5. CHECK CURRENT RAT INGS AND S ERIAL NUMBERS AGAINST SINGLE LINE DIAGRAM TO ASSURE THAT BREAKERS ARE PROPERLY LOCATED IN SWITCHGEAR AT INSTALLAT ION .

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