leonard r crow - attracting copper, aluminum & other non-ferrous metals - extra

8/12/2019 Leonard R Crow - Attracting Copper, Aluminum & Other Non-Ferrous Metals - Extra

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G, S & AG

LS LMAGS

AAG ALMM &

H -S MALS

by

Leonard R. row

EDUCATIONAL SPECIAISTIn evlopmnt of

Elrica sruco

DIRECTOR OF REEARCH AND DEVEOMENT

Usl Snic Compy, Inc.

THE SCENC BOOK PBLSNG CO

V

9 5


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Repinter.s ote

I am ve nteested n communcatng wthndivdas and o companies that hae in the past,

o ae cuenty usng ths magnet technoogyShoud you know of addtional aceooks ec. or

ndduas that have knowedge elating to thssubjt matte pease contact me at:

Benjamn eming1734 Vewpont D

Fayettelle Akansas 72701

o e-ma

bnenguaked

NOICE

Some of e devices and consrucons lusraedand described hs book are covered by eerspae Desgners ad mafacrers ae waredo ceck he pae siuaion horougly, before coporag any o e embodimens descrbedherewih io heir own designs or consrucos

lusrao or descrpio s boo mus nobe consrued to Impy ha a device sysem o consucio shown herein Is commo propery avai-abe for pubc use by anyoe. Accordgy, ere-fore, te publishers or auor wl o assume ayresponsbiy for damages arsing ou of ligaioinolvg Irgeme sus relave o ay sysemconsruco or apparas descrbed erei


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TOMAGNTS O SA ONSTTON OR TATTAON O NON-OMAGNT MTAS

Magnetism is one of the most interesting and mysteious aswel as one of the most impotant physical phenomena knownThough its action we generae and utiize the enormous qantities of eectrical we which make possibe modern industry

and modern iving. Many important principles of electomagnetism can undestd fom the study of an electomagnet,invented ad designed by the autho, which aacts non-ferromagnetic metals

Everyone hs eeimented with magnets and observed theiaraction fo ion filigs naiS nd othe smal aticles ofion and steel ome of you ill have seen lage electomag

nets attached to cnes pick p tons of scap steel and move it

aut with ease. Tons of iro ae hed fimly to the magnetwith an invisible foce and are released by the fip of a switchYou have also obseved that hie ion is atracted with suchfoce othe metls such as auminum coppe and sive aeuaffected his pincipe is often used to sepaate iron fom

non-ferous mels No dout you have used a magnet to detemine whethe a ckel plated scew had an iron or bass seYou may aso have noticed tht aternting curent is appIed


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2 ELCTROMAGNES

igur 2

to an ordinary electomagnet, non-magnetc meals of goodeecrica coductivty wl acuay repeled. n view o aof e ave wil be mos interestng o learn how magetsmcan be used o atract nonferromagneic meals

In 1934 he author desgned equpment with whch was possible to demonstrate princpes whereby non-erromagneicmetals migh be atraced by a special magne In 940 heauhor completed the deveopmen ad construcion o an eecromagnet wh would actualy aract meals sch as aluminum, copper and slver. In act the magnet would atract any

ea o air or go electrica conductvity owad the endof 1947 the author completed he desgn and consructon of amuch mproved eecromagne or he aacton nonerrousmeas he detas and descrpion of which ae ncluded n thisarce The special electromagne s iusrated n Fgure .In Fgure 2 he magnet wih ts a horionta s shownsupporting a heavy pece o copper I Fgure 3 two pieces oauminum have en added to he original pece o coperFigure 4 shows te magne suprtng wo sUver dollars Thesze of he magnet ustraed by comparison wh he siverdolars a the maget may aso be used to attrac ron isidicated cleary n Figure 5.

Beore considerng the detas o consruction and prncpleso operaion of the speca elecromagnet et us revew someof he sc pricpes o magnetism and elecomagnesm

DESIGN CONSTRCTIONA OPERTG PRCES 3

ire 3

We wl not ony observe tha nonferromagneic metas can attracted to an eecromagnet t w also gan the peasure ondersanding its prncpes o action

Oersed in 189 was the fs to show tha a current carryingwre was surounded by a magnetic !eld He dscovered ha acompass neede algns tse a righ ages o a wre carryig

Fie"


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LETROMAGNTS

Fgure

a ltr urrt hu it i w at a ru lart a Fiu 6, thr wi a a Id aut h wir drt hw. h urr drt arda

'CEl

Figure 6

DSIGN, CONSTUTION, A OPATG PRCS 5

wih h vta xplaa tha urr lw fr piv av

a pa pad abv th wir wl pt h dri hw I Fur 7A pit at rht a h urr arryi dur h pa d wl pt thdri ta h lux li ar vi H th urrt rvr d a I Fur 7-B h pa wll p h pptdrti a hw ad w w th ux li hav rvrdh ditO-Cm

Fgue

w pa a ubr ati d r pa auta urr arryi dutr I h ar hw i Fur 8h pa dl w pIt drU lurad

I

1A B

Fig


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8 ELECTROMAGNETS

Figure 1

will be opsite to the flux lines at No. 2 conductor and thereare no flux lines encircli th conductors The two conductorswill repel each other Thus we see that flux lines which travelin the same direction, as in the space between the wires pro-duce repulsion

'

From the foregoing we see that such non-ferromagneticmetals as copper condctors can be moved about in magnetic

fields becaus of the magnetic lines of force that are prodedby currents flowing in the conductors (metals) themselves Thisdoes not necssarily, indicate that it is possible to magnetizenon-ferromagnetic metals (such as copper or aluminum) in themanner that we do a piece of steel or other ferromagnetic metalhowever it is quite interesting to note the striking similiarity

,

of araction nd eplsion as shown by Figres and .In Figure , by the se of conventional symbols, two con

dctors are shown carrying current The circles with a pls(+) at their centers represent the cross section of two condctors carrying crrent away from the observer The directionof the magnetic flux aut the conductors is also shown in relation to the direction of crrent flow Jst low the two condctors are two ermanent magnets with an indication of the direction of flux lies of each magnet in relation to its ' polarityNote the imiarity i n the direction of the flx lines between th

DESIN CONSTRUCTION AND OPERAT RCLES 9

ATRACION

Figure 13

magnets and etween e conductors carryingc rrent. I is

shown i the drawing and can easily be demonstrated that there

is attractionbtween the two copper (non-ferrous) condctors

when theflx lines between them are in opposite directions;

likewise, there attraction between the two pieces of steel

(peranent agnets when theflux lines etween the are in

opposite directions.

In igre 4, illstration is made of the same two conductors

and permanent magnets except here the crrent in the right hand

condctor is represented asflowing toward the oserver, such

deSgnation being a dot ( at the center of the circle (conductor).

Also, it is to be noted that the right hand permanent magnet has

its polarity reversed to that of Figre 13. Here the magnetic

lines of force etween the two conductors are in the same direc-

tion thereby producing replsion between the two copper

EPULSO

Figure 14


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12 EECTROMAGNETS

T uhe usate he efect f the magneic field pucedby the current fw hugh this p cnduc Figure 6shws a lge l suspended withi ad a he cete f thelp The age curet flw thugh he p cnducr pr-duces a magnetic field aut he p whch magetizes the largenai Visul p that he lge ai is magneized is shwn bythe fact that it attracts ad hds i suspesin a lage numbe smal nals

T pceed a step furthe, we sha nw sudy igue 7.ee a few arge nails are shw whi the op cpper we

Figue 7

and it is be ned ha a these ails have cme magnezedby the mageic ield abut the curent caying cnduct Eachf the ails has cme a maget ad they al epe each herbecause ike les o a magnet epel These nail magnets havehe same laiy cause they ae all the same side f hecnducr and ae subject ies rce that are lwing Inthe same directi Alhugh he cuent lwing hugh thecpper lp is aleatig t neveheless prduces a magneticlux that a any insant is the same diectin thugh all theais As he ield segh ad plarity ay ne ni chages,it likewise changes thrugh all he thes Cnsequently, theais have like rities at all times wch esuls i epulsinbetwee them since like ples epel

Let us assume hat the mageic lux f a give aenatinis flwing dwwad n the iside f the cppe lp cnducr

DSGN, CONSTRCTON, AND ORATN PRCPL 3

As he magneic ux circles aut the cducr it wil lw up-wad n the uside the lp Theer e, a nai placed n theutside the lp wil hve he ppsite plaity t e n theiside ad attracti will result between a nail n the utsidead ne he iside since uike ples attract igure 8 shwsths very clealy whee several ails n the Inside f the lpcing t the aUs the uside the p.

gre 18

As has previusly en stated the magnetic fce aut acurret carryig cductr s quite small unless a very largecurret is made flw thrugh It de t cceate he

actin and incease the fce, the wie may fmed in sev-eral ts as shwn in igre 9, Here thee ae three turnsrming he cl (helix) theeby ccentratig the magneti c ines fce alng sevea inches the cnduct it a sma space,which shws hw the magetic stength pduced by a given cur-en fw ca be cncenated.

t is a wel esablished act tha he mageic rce (stegh) a ci Is diectly prptina t the ampee turs f theci T find the ampere turns a ci it is ecessay t muiply the num turns i the cil by he current lW, i amperes, thugh the cil emple, a c uns cary-Ing 1 amperes is equivalen t a cil 10 turns carying 0ampees, assumig f crse hat all her actrs culd made equa in each cil

The magetic frce betwee tw paralel cnducs may


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4 ELECTROMAGNS

Figure 19

augmented by concentra1ng the magnetc feld and thereby in-creasng the force by formng the conductors nto cos as shwin Figure . Here there would many fux nes nkng hcoUs ad tus pul tem together so long as the currens

Fge 20

though th cos were In the same drection U the eads toone of te cois were reversed therey reversng the dectioof current flow trough that col the two cos woud repel eahother.

DSIGN, CNSUCTN, A PEATG CS 5

very strkng demonstraton of te attractve ad repulsvefOrces pruced y the magnetc feds of two cols s ustratedby gures 2 and 22. n gure 21- two cois are shown suspended and separted a cosderable dstance before current was

A Bgure

made to flow through them current flow through the two coBsn the same drecton caused the attractive force to be so greatthat the coils jumped together tough seera nches as shown gure 21-B

By suspending the two cos so tat they touched each otherfore ssg current though them, they were as show ngure A. ut as soon as current was made to fow thoughthe two cols n opste drectons they repeled each other nthe maer shown n gre 22B.

n order to concentrate and utilze effectvely the magnetcines of force that ae pruced y a current flow through aconductor for most appcations it s advsale to use ferromagnetc metals such as steel to conduct the flu ecause ars a very or conductor of magnetism and ferromagnetc metalssuch as steel are eceptonaly go magnetc conductors. Thats, a offers a gh reluctance whe ferromagnetc metas offer


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6 ECTROGNS

A B 22

low rectance . How a ferromagnet c met my used to ilstrate this fact 1s clearly shown y the se of the soft steelcores shown n Fgres 23 and 2.

he foregoing eerments shoud sucent to gve a veryclear pictUre of how mgnetc fux Is pruced y current Clow

e 23

DSGN, CONSTRUCON, ND OPRTG RNCES

iue 4

a someing e reation of the lux to the current he discssion s far has en concerned wth the me

cncal force prduced y magnetism We must also study'

he

eect of magnetsm n nducing a voltage or current we areto understand the attraction of non-magnetc etas by the specal eectromagnet.

After Oersted dscovered the magnetc feld at a conductor carryng crrent 8, many expermenters attempteto prouce the nverse effect. That s, they tred to produce acrent y means of a magnetc feld. Al were nsccessfuluntl FaradayS hstoric experments n 83 araday showedthat a current, or more correctly an electromotve force, wasnduced when the amount of fux threadng a col was changng,


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18 ELECTROMAGNETS

but that no voltage was induced by a steady magnetic field regardless of how strong it might b made. Let us consider a fewsimple experiments concerning induced electromotive force.

Let the bar magnet of Figure 25 be thrust quickly into thecoil. The d-c voltmeter with a zero center scale will deflect

Figre 25

momentarily either to the right or left depending upon the polarity of the connections. Let us say it deflects to the right.Next, the magnet is withdrawn quickly the voltmeter will de

flect momentarily to the left.Now let the bar magnet be replaced by a coil r solenoid and

a battery as in Figure 26 Upon closing the battery circuit the

Fgre 26

DESIGN CONSTRUCTION AND OPERATING PRINCIPLES 19

voltmeter will show a deflection and will deflect in the oppositedirection upon opening the circuit. The magnitude of the voltageinduced with the arrangement of Figure 26 would be quite small.However the magnitude of the induced voltage can be greatlyincreased by inserting a laminated iron core in the solenoid asin Figure 27 The introduction of an airon core causes a great

Fgure 27

deal more flux t be set up in coil B for a given current in thecoil A thus increasing the induced voltage. We say the ironcarries flx more readily than air because it has a higher permebility

Let us consider the direction of te induced electromotive

force in Figure 27. Un closing the switch current will flowin the diection of the arrows on the solenoid winding and thusproduce a north pole at the right hand end of the iron core. Nowwe must use a law discovered by Lenz in 1834 which is calledLenz' Law. The law may be stated as follows: Any inducedelectromotive force tends to set up a current in such a directionas to oppose the action which produced the electromotive force.Thus upon closing the switch n Figue 27 a current would beinduced in coil B in the direction indicated because such a current would set up a magnetic flux which opposes the flux set upby a north pole at the right hand end of the electromagnet core.Figure 28 shows that coil B will be repelled since flux lines inthe same direction repel. We might also consider that the current in coil A is prucing a north pole at the left side of coil Bwhich is repelled by the adjacent north pole of coil A. Uponopening the switch the urrent in coil A would be reversed


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2 CA

'-

Ie

v(dcasn). Accodn to nz' law, th ndcd cnt nco B wod st p a mantc n whch wod nd to pvntth dcas of h xstn fx. nd s condton th fxn co B wod vsd, and co B wod b attactd towad th ctomant A s 26 and 27 show tns ofw havn voas cd n thm cas of a chann cnt n th sonod s vdnt hat a coctn non-fomantc wash wd hav n a sma m.

Yo ca that fo dct cn, ndcd voas and cnts aa oy dn swtchn opatons and that th sno dcd vota dn stady cnt fow adss o howsto th fds may . HowvJ h atho'5 spca ctomant ts atnatn cnt, and w a t dstan

th opaton o th ctomat w mst consd a fw oth chaactstcs o atnatn cntAs yo alady ow atatn cnt h th popty of

vsn ts dcton o !ow many tms a sco o thsa 6 cyc cnt t fows n on dcton fo 1/12thof ascond an thn n th opst dcton fo th nxt 1/2thscond Howv t dos not chan abpty fom say 1 amps n on dctn to 1 amps n th oh dctonhs wod q a vy apd chan n cnt at th vsas and consqnty ndc hh voas nstad t chansn th ada mann lstatd n 29. hs cv scad a sn wav and psnts many nata motons as was atnatn cnt. o amp, psnts h voctytm aton of a wht sspnd fom a spn a st ntooscaton Consdn atatn cnt, h pont A

DG, CRC, A PRG PRC 2

"

igu 2

/o

M

,/

psnts zo cnt, bt h cnt s ncasn. fact, s ncasn most apdy at ths pont of th wav h pontB psnts maxmm cnt, bt th cnt has stoppd ncasn Byod nt B th cnt dcass At pnt Cth cnt s zo and dcasn most apdy om C to Da th ffct s ad bt n th oppost dcton hsw s that wth atan cnts, th cnt s chancontnosy cpt at h paks of th wa, that s, cp atponts k B and D nc chann cnt pcs chanf ad chann f podcs ndcd voas ad cntn condctos nd by th chann f thn atnatn c

nts podc sma atnatn ndcd ctomotv focsow t s consd an on co sonod connctd to anatnatn cnt soc wth a non-fomantc condctnwash (shot cctd sconday) sspndd fo as n 3 At som nstant th sonod cnt s ncann th dcton ndcatd h dcton of th dcd cntn h wash w as ndcatd bcas an ndcd votas aways n th opst dcton to th cn vota. hsth wash w d fom h ctomant bcas thf ns podcd y th cnt fow n th ash podcsa noth po adjacnt th nd of th ctomant nast thwash, a th cnt ow toh th ctomant podcs a noth p adjacnt th fac of th wash nast thctomant

h psv foc td btwn th fd of an ac


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22

AC

ELECTROMAGNETS

SC

, I, , .

: :> - ,

\ "' v;

I \

Fire 30

elecomaget ad the Held of a shot cicuited seconday(washe) is stikngy shown by a study of igues 31 and 32.igue 31 shows an electomagnet and with a means povided

fo connecting it t o a soce of alteating cuent. The electomaget has an ee coe ove which ae placed thee alminm wahes esting on the end of the magnet coil pimaywindig. When the mnet winding is enegized by the atenag cuent the magetic field podced by the coi wdingad hat set up by the (seconday auminm washe cuentpoduce epulion and the washes ae thown violently ito heai, as shown in ige 32.

ie 31

CONDUTIVEWASHER

RPlLf

TO .OURC

F 32

DESN ONSTRUCTON A OPERATG PRLES 23

Let two wahes placed nea the end of the electomagetas in igue 33 ome of the fux fom the eectomaget wthead o ct thogh th of the washes, and at a paticulainsant cents in the two washes and in the electomagnetwinding will have the diections indicated ee we have one ofthe most impotat opeating pincipes of the special electomagnet fo atactig n-magnetic metas

e

F 33

ompae the situation of the cuents in the two washes ige 33 with the cents in the two cois of iges 2 and21 The cen ae fowing in the same diection and as icated in igue 33 thee wil flx lines inkng the twowashes which will tend to pull hem toether oweve sincethe foce of epulsion beween the ac electomagnet and hwashes is vey stong is dfict to show by the aangementof ige 33 hat thee is an attaction between the two washes the cen in the

'two washes wee suficienty age the

washes wold ped ogethe with consideable foce The

hoe in eithe washe i immateia since fu passes thoughnon-feomagetic mateias just as does though ai

With thi fndamnta pinciple mid that thee Is attaction between the two washes igue 33), let s now conside the constuction and fields of the special electomagetwhich wi atact ofeos mateias The elecomagetis show diaamacaly In ige 34 The few tns showepesent the ente winding of the electomagnet ige 35 sa coss section of the inne and oute laminated ion coeswhich eend the entie aa length the electomagnet. ge 36 shows the inne coe and he goup of coppe washeswhich tiay fl the anna space between the inne andote coes These coppe washes occupy this space in onlythe face e the maget The top washe shows cealy inthe phoogaph of igue 1. The complete eectomagnet is


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24 ELECTROMAGNETS

AC W"'NG

ig 34

mouted o a suortig stand for coveience i demostratigits qe ability to attract o-ferromgetic metals.

We ow know the costrctio of the eletomaget ad avestudied the essential magetic theory volve i ts operatio.

LITED

g 35

DESIGN, CONSTRUON AND OPERATG PRCLES 25

AMINADCNRCORE .

g 36

With tis iormato it wil ot dfficlt to explai itsperformance

Figre 37 is a cross sectio of the magnet wth the fourcopper washers removed The circles at the top ad ttomrereset the widig. The dots ad crosses idcate tat curret is directed ot of the paper ave and ito the pper lowat the ist at cosidered We ow from the right had rle tat

Fre 37


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30 ELECTROMAGNETS

N

MGN FD K IY PL

Figue 2

SRE

formed Into oe contnuos cyldrical pole aut the iner poe.But addton te ceter pole o te ahors specal eectro-maget as a sort cicted (copper waser) secodary sur-roundng te le ed

U we mody the thee legged eectromagnet 01 igre 42 baddg a sort ccuted copper secodary o te center coreleg e mied electromaget will lok le gure 43. Tisdevice will terefore come a ompund saded pole electromagnet ts elecoagnet a second secodary tertiarypiece of copper Y wll ave a rce exerted on it te drectonsown I t s paced over poes A ad C but wil ave a orceerted on it e opsite drecto i paced over poes B

, y I-COPPERORp Nz I SHETx-

) TOAC. Fr 43

DSGN, CONSTRUCTON, AND OPERATG PCES 31

ad C Ts mes tt the tertary Y wll hve forces eertedon it from poles A ad B wic wll case a strong cetergacton of te tertary over pole C Here aga we ve te samecodton te authrs speca eectromagnet ecept at polesA ad B are ormed to one contuos cydrical pe atte ceter pole

A grap c lstraton of te estence of e travelling m ag-etc ed prced by the specal electromaget s illstratedby a actl potograp (igre 44) Here two almnm llsare placed upo te face o te electromagnet ad wh te prmary crrent turned on te amm bals rotate very rapdly

Te curved arrow aove eac all ndicates te drecton o rotatio of te l

Several interestg tings are to be noted abut te attractive propertes of tis specal electromaet Te mass to be

Fr 44


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Excerpt from the book "Magnetic Current" By ED Leedskalnin

When you were making the small magnets with a single copper wire you wastedtoo many North and South Pole individual magnets. You only got in the steel wire verysmall part of the magnets that came out of the copper wire. You are still wasting the

North and South Pole magnets. You do not get one half of the magnets in the steel oriron bar from those which are in the coil. To get more magnets out of a coil put the coilin steel or iron tube, then the tube outside the coil will be a magnet the same as thecoil's core, but the magnet poles will be opposite. it means at the same coil end if thecore end is North Pole the tube end will be South Pole. In this way you will get almostagain as much magnet out of the coil and in the core and tube.


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'

(

)


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32 ELECTROMAGNES

attracted may subec o a repulsive force from the primaryHeld an therefore should b of a size not larger han he spacewihin the cylindrica e Since the current in he primarywining Is generally oosie to the current in the mass to araced, that mass shoud of a general size and shape o liewithin he cylindrical le pece undary and should o exendover into the ifuence of he primary coi

When he circumerence f the mass to atraced is largerthan the cicumference of he cylindrca pole, he repusive

force exered un it by he primary winding increases veryrapidy wih an increase n is size he non-ferrous mass saso reled i is approximately of he same periphera imensions as he inside dmnsion of the cylindrica core bu isnot closey adjacen hereo he obect to atracte shoulbe adapted o he field and soud generaly be placed fairlyclose to the magne unless i is Quie a bit smaer tha the inside dimension of the cyndrica poe face. is possibe tomake the conductive mass to b attracte "ump a considerable

dstance o affix se to the aractor b y havig he noferrousmass of consierably smar dameter tha the cyinricacore

By experimening wih armatures of eren sizes suspendeda various disances from the atracor face i has en found

hat a region or zone of atraction exss which is conical inshape. A coductive obect ace with is principa conductingpah wthn ths cone is atrace he se of this cone

Fr 45

DESGN ONSRUON OPERG PRNS 33

substantiay coincides wih he face of the attractor and has isvertex on he axs a a distance from the attracor as illustratedn gre

igre shows a siver half or suspended near he atractor face. n his f gure the half dolar is suspeded so aso have ts pane perpendicuar o the plane of the aractor face

re 46

bore he magnet s energized But the nstan current flowsthough he primary winding of the eecromagne he ha oar

urns so tha is pane is paralel with he pane of the attractorace as shown in igure 7 and is attrace with considerabeforce his resu is exacly opposite o he resul to be expectedhe silver doar were paced in he fiel o a ordinary alternaing curren elecomagnet he atracor in this specialeecromaet were o prese to exercise ts iuence thecoi wou hen urn with its pane perpendicuar to the pane ofthe electromanet faceU a non-ferrous ring washer or isc with a pane dimesion

consieraby in excess of the cyindrica poe face dmensio ispaced near the face of this speca eecromagnet the the obect s ou in he inluence of the primary c an as thecase of a conventional electromagne the obect woud be repele.


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34 LECTROMAGNES

Fgue 47

In Fgure 48 a large alumium dsc s suspeded n fo ohe eectromagne wh s pane paale wit te attraco facebefoe the eectromagne wndng s eegzed wh curentBu the insa hat curent flows toug the electomagne'sprmary widng e large dsc s epelled wit geat foce and

fally comes o est wt ts plane pepedcua to the face ofte eectomagne (see Fue 9) and emais tis posionas log as e cuent coiues to fow hough he primayWidng of the eectomagne

I s altogete ssible o modfy e seconday atacto)elemen by substug a wdg n pace of the coppe washes.Such a aangemen s show y Fgure 50.

Hee a means s povded fO shr ccung he secodaycol by cosg e swch o poso A as ustaed By hsarangement the swtc may b cosed, causg he so crcuted widng o ac ke the coppe washers poducng atraco of a non-ferous mass whe used conjuncto wte prmay wding a cydca coe Ten te swtch maye opened causng e non-ferous mass o b epelled icete only fx nes now poduced by he elecromage ae oe

DESIGN CONSRUCTON, AND OPRATG PCES 35

Flgu.e 48

poduced by e primary. By te arageme show hs

fgure the swtc may e cosed o posito B heeby conecg

e wndingto te same alterag curren sorce o wch te

prmy wdng s cOMected b a manner so as o opse

te pmay wdng By s means attraco of te on-fer

ous mass ca also be accomplshed Ts aragemen wc he secoday (ataco Is coneced so a to e n pase

opston o the prmay s ifeor to he form wch he

secoday (atacto) has curret nduced I I. e reason fo

ts is tobatuedo he fac ta te curren iduced nthe

mass o batacted (ertay) s no exacly opos it n phaseto the pimay curen and heefore wl no be exactly inpase wt he cue e secodary whee he secondary sfed in exact opposto o e prmay en curre n hesecondary s nduce s more nearly exacty n pase wh

he cuen n he amare whch resuls In maxmum aac-

ton

-In he Instance whee e pmary and seconday (atraco)


34/35

36 ELECROMAGNE

Figre 49

are connected n phase opposion o he sae alernaing curen source, he secondary (aractor) crcut may b modid50 a to afford soe phase ag. An arrangement or ths odifcaion s shown in Figure 5 where a ressor may b connected I series wih he attracor wning y closng the swtch

to posiion B. his circut can e conneced n paralel Pposon with he priary and y adjustmen of he variale rheosaa fairly coparae phase lag may b produced Howeer tis Ifor o consrucion (even wth a reSstor) n whch he secodr (atractor s connected n phase oppositon to the priayS neror o he orm n whch the secodaryh current induced n t

he arrangemen shown n Fgure has soe advanagesfor educaona deonsraons een hough It s no as efcenas he copper washer ype The swichng syste allows amuch greater lexility in ts use snce he equipmen ay b

DEG CORUCTO, AD OEAG RNCE 37

Figre

used oh as a special electroagne for non-errous aerasand as a convenionl eectromagne

ue o he fact ha hs eecroagne s an open core device power factor is not unty his resuls n raher large powerconsupon and n heatng of he wnding although he heatingay e reduced consideray y usng very large wire. Forlae electroagnes o ths kind I ay e necessary o prove means or circuaing a coolng medium hrough h prary and secondary olow copper uing could e used in theconsructon of exremely arge elecromagnes o his ypeGeneraly speaing capaciors ay e used n correctng thepower facor of his ype eectroagnet therey reievng hepower supply line o much of Its watess curren urden andhus helping to eep he electroagnet prary wndng coo

Fgure 51 s a graph showing amount of power facor correcon ha was oaned wih static capacitors of 100 icrofaradsused In conuclon with one of the auhors' elecroagnets forhe atracion of non-ferrous meals.

ae shows the change n current line voage, powerfactor, and phase angle obtained hrough he use o statc capaciors in conuncion wth the eectroagnet he elecromagnet and capacitors were those used to otain he graphshown n Figure 1. n order to correc he power facor yuse of sac capacors he capactors are of course, shuntedacross he Inpu erminals of he prmary winding of he eectromagne


35/35

38

,350

.40

.30

.320

.310

.30

201 28.270

a

260250240230/

ELECTROMAGNTS

V7

10 20 0 0 0CAPTAE IN MfARADS

Figure 51

Table

'0 0

.

90 0

CAPACTORS USED FOR POWER FACTOR CRRECTIN

Cpcne Ln. ine Power Ftr Phase Angen d E P

E

0 16 0 3 ".

50 .8 O 289 72 8'

1 110 48 ego 42'An eectromagnet for attracton of non-ferros metals such

as has en descrd canot made effectve for the attrac

ton of smll peces of nonferros metals when sed on a owfreqency power sorce. In order to use ths type eectromagnet for the atracton of smal particles or peces of nonferrousmeals, s necessary tht desgned and constructed fororaUon on a sppy of hgh freqency current The freqencyrequred wi deend on the sze of he peces or partcles to beattracted

leonard r crow - attracting copper, aluminum & other non-ferrous metals - extra

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