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N. TESLA.
SYSTEM OF BLEGTRI CAL DI STRI BUTI ON. , .
No. 3 8 1, 9 7 0 . A PatentedMay 1, 18 8 8 ' .
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UNI TED STATES ,
PATENT OFFI CE.
NI KOLA TESLA, OF NEI V YORK, N. Y., ASSI GNOR OF ONE- HALF TO CHARLES
F. PEOK, OF ENGLEWOOD, NEW JERSEY.
SYSTEM OF ELECTRI CAL DI STRI BUTI ON.
SPECI FI CATI ON forming p art of Letters Patent No. 3 8 1, 9 7 0 , dated May 1, 18 8 8 .
Ap p l ic ation ?l ed Dec ember 23 , 18 8 7 . Serial No. 25 8 , 7 8 7 . (No model .)
To al l whom, it may c onc ern.
Be it known that I , NI KOLA TEsLA, from
Smil j an Lika, border c ountry of Austria- Hun
gary, now residing at New York, in the c ounty
and State of New York, hav e inv ented c ertain
new and useful I mp rov ements in Systems of
El ec tric al Distribution, of whic h the fol l owing
is a sp ec i?c ation, referenc e being had to the
drawings ac c omp anying and forming a p art of
the same.
This inv ention rel ates to those systems of
el ec tric al distribution in whic h a c urrent from
a singl e sourc e of sup p l y in a main or trans
niitting c irc uit is c aused to induc e by means
of suitabl e induc tion ap p aratus a c urrent or
c urrents in an indep endent working c irc uit or
c irc uits. -
The main obj ec ts of the inv ention are the
same as hav e been heretofore obtained by the
use of these systems - v iz., to div ide the' c ur
rent from a singl e sourc e, whereby a number
of l amp s, motors, or other transl ating dev ic es
may be indep endentl y c ontrol l ed and op erated
by the same sourc e of c urrent, and in some
c ases to- reduc e a c urrent of high p otential in
the main c irc uit to one of greater q uantity and
l ower p otential in the indep endent c onsump
tion or working c irc uit or c irc uits.
The general c harac ter of the dev ic es em
p l oyed in these systems is now wel l under
stood. An al ternating- c urrent magneto- ma
c hineis used as the sourc e of sup p l y. The c ur
rent dev el op ed thereby is c onduc ted through
a transmission- c irc uit to one _ or more distant
p oints at whic h the transformers are l oc ated.
These c onsist of induc tion- mac hines of v arious
kinds. I n some c ases ordinary forms of induc ~
tion- c oil hav e been used with one c oil in the
transmitting- c irc uit and the other in a l oc al
or c onsump tion c irc uit, the c oil s being differ
entl y p rop ortioned ac c ording to the work to
be done in the c onsump tion- c irc uit that is
to say, if the work req uires a c urrent of higher
p otential than that in the transmission c irc uit
the sec ondary or induc ed c oil is of greater
l ength and resistanc e than the p rimary, whil e,
on the other hand, if a q uantity c urrent of
l ower p otential is wanted the l onger c oil is
made the p rimary. I n l ieu of these dev ic es
v arious forms of el ec tro- dynamic induc tion- 5 o
mac hines, inc l uding the c ombined motors and I
generators, hav e been dev ised. For instanc e,
a motor is c onstruc ted in ac c ordanc e with wel l
understood p rinc ip l es, and on the same arma
ture are wound induc ed c oil s whic h c onstitute , 3
a generator. The motor- c oil s are general l y of
?ne wire and the generator- c oil s of c oarser
wire, so as to p roduc e a c urrent of greater
q uantity and l ower p otential than the l ine- c ur
rent, whic h is of rel ativ el y highv p otential , to 6 c
av oid l oss in l ong transmission. A. simil ar ar
rangement is to wind c oil s c orresp onding to
those desc ribed in a ring or simil ar c ore, and
by means of a c ommutator of suitabl e kind to
direc t the c urrent through the induc ing- c oil s 6 5
suc c essiv el y, so as to maintain a mov ement of
the p ol es of the c ore and of the l ines of forc e
whic h set up the c urrents in the induc ed c oil s.
WVithout enumeratingthe obj ec tions to these
systems in detail , it wil l suffic e to say that the 7 0
theory or the p rinc ip l e of the ac tion or op era
tion of these dev ic es has ap p arentl y been so
l ittl e understood that their p rop er c onstruc
tion and use hav e up to the p resent time been
attended with v arious diffic ul ties and great 7 5
ex p ense. The transformers are v ery l iabl e to
be inj ured and burned out, and the means re
sorted to for c uring this and other defec ts
hav e al most inv ariabl y been at the ex p ense of
effic ienc y.
The form of c onv erter or transformer whic h
I hav e dev ised ap p ears to be l argel y free from
the defec ts and obj ec tions to whic h I hav e al
l uded. Whil e I do not herein adv anc e any
theory as to its mode of op eration, I woul d 8 5
state that, in so far as the p rinc ip al of c on
struc tion is c onc erned, it is anal ogous to those
transformers whic h I hav e abov e desc ribed as
el ec tro - dynamic induc tion - mac hines, ex c ep t
that it inv ol v es no mov ing p arts whatev er, and 9 c
is henc e not l iabl e to wear or other derange;
ment, and req uires no more attention than the
other and more c ommon induc tion- mac hines.
I n c arrying out my inv ention I p rov ide a
series of induc ing- c oil s and c orresp onding in- 9 5
duc ed c oil s, whic h, by p referenc e, I wind up on
a c ore c l osed up on itsel f- suc h as an annul us or
ring subdiv ided in the usual manner. The
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two sets of c oil s are wound side by side orsu
p erp osed or otherwise p l ac ed in wel l - known
ways to bring them into the most effec tiv e re
l ations to one another and to the c ore. The
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induc ing or p rimary c oil s wound on the c ore
are div ided into p airs or sets by the p rop er
el ec tric al c onnec tions, so that whil e the c oil s of
one p air or set to c o- op erate in fix ing the mag
nc tic p ol es of the c ore at two giv en diametric
al l y- op p osite p oints, the c oil s of the other p air
or set assuming, for sake of il l ustration, that
there are but t\ v o tend to ?x the p ol es ninety
degrees from suc h p oints. \ Vith this induc
tion dev ic e I use an al ternating- eurrent gen~
erator with c oil s or sets of c oil s to c orresp ond
with those of the c onv erter, and by means of
suitabl e c onduc tors I c onnec t up in indep end
ent c irc uits the c orresp onding c oil s of the gen
erator and c onv erter. I t resul ts from this
that the different el ec tric al p hases in the gen
erator are attended by c orresp onding mag
netic c hanges in the c onv erter; or, in other
words, that as the generatorc oil s rev ol v e the
p oints of greatest magnetic intensity in the
c onv erter wil l be p rogressiv el y shifted or
whirl ed around. This p rinc ip l e I hav e ap
p l ied under v ariousl y~ moditied c onditions to
the op eration of el ec tromagnetic motors, and
in p rev ious ap p l ic ations, notabl y in those hav
ing Serial Nos. 25 2, 18 2 and 25 6 , 5 6 1, I hav e de
sc ribed in detail the manner of c onstruc ting
and using suc h motors. I n the p resent ap p l i
c ation my obj ec t is to desc ribe the best and
most c onv enient manner of whic h I am at p res
ent aware of c arrying out the inv ention as ap
p l ied to a system of el ec tric al distribution;
but one skil l ed in the art wil l readil y under
stand from the desc rip tion by the modi?c a
tions p rop osed in said ap p l ic ations, wherein
the form of both the generator and c onv erter
in the p resent c ase may be modified.
I n il l ustration therefore of the detail s of
c onstruc tion whic h my p resent inv ention in
v ol v es, I now refer to the ac c omp anying draw
l ugs.
Figure 1 is a diagrammatic il l ustration of
the c onv erter and the el ec tric al c onnec tions of
the same. Fig. 2 is a horizontal c entral c ross
sc c tion of Fig. 1. Fig. 3 is a diagram of the c ir
c uits of the entire system, the generator being
shown in sec tion. '
[use a c ore, A, whic h is c l osed up on itsel f
that is to say, of an annul ar c yl indric al or
eq uiv al ent form~ ~ and as the efl ic ic nc y of the
ap p aratus is l argel y inc reased by the subdi
v ision of this c ore I make it of thin strip s,
p l ates, or wires of soft iron el ec tric al l y insu
l ated as far as p rac tic abl e. Up on this c ore,
by any wel l ?known method, I wind, say, four
c oil s, B B B B , whic h I use as p rimary c oil s,
and for whic h I use l ong l engths of c omp ara
tiv el y fine wire. Ov er these c oil s I then wind
shorter c oil s of c oarser wire, 0 C O O , to c on
stitute the induc ed or sec ondary c oil s. The
c onstruc tion of this or any eq uiv al ent form of
c onv erter may be c arried further, as abov e
p ointed out, by inc l osing these c oil s with iron
as, for ex amp l e, by winding ov er the c oil s a
l ayer or l ayers of insul ated iron wire.
The dev ic e is p rov ided with suitabl e bind
ing~ p osts, to whic h the ends of the c oil s are
l ed. The diametric al l y- op p osite c oil s B B and
B B are c onnec ted, resp ec tiv el y, in series, and
the four terminal s are c onnec ted to the hind
ing- p osts 1 2 3 4- . The induc ed c oil s are c on
nec ted together in any desired manner. For
ex amp l e, as shown in Fig. 3 , G C may be c on
nec ted in mul tip l e are when a q uantity c ur
rent is desired- as for running a group of in
c andesc ent l amp s, D ~ whil c G 0 may be in
dep endentl y c onnec ted in series in a c irc uit
inc l uding arc l amp s or the l ike. The gener
ator in this system wil l be adap ted to the c on
v erter in the manner il l ustrated. For ex am
p l e, in the p resent c ase I emp l oy a p air of or~
dinary p ermanent or c l ec tro magnets, E E,
between whic h is mounted a c yl indric al arma<
ture on a shaft, F, and wound with two c oil s,
G G . The terminal s of these c oil s are c on
nec ted, resp ec tiv el y. to four insul ated c ontac t
or c ol l ec ting rings, H H H I I , and the four
l ine c irc uit- wires L c onnec t the brushes K,
bearing on these rings, to the c onv erter in the
order shown. Noting the resul ts of this c om
bination, it wil l be observ ed that at a giv en
p oint of time the c oil G is in its neutral p osi
tionandisgeneratingl ittl e or no c urrent, whil e
the other c oil , G , is in a p osition where it ex
erts its max imum effec t. Assuming c oil G to
be c onnec ted in c irc uit with c oil s B B of the
c onv erter, and c oil G with c el l s B B , it is
ev ident that the p ol es of the ring A wil l be
determined by c oil s B B al one; but as the
armature of the generator rev ol v es, c oil G de
del op s more c urrent and c oil G l ess, until G
reac hes its max imum and G its neutral p osi
tion. The obv ious resul t wil l be to shift the
p ol es of the ring A through one- q uarter of
its p erip hery. The mov ement of the c oil s
through the nex t q uarter of a turn, during
whic h c oil G Yc nters a ?el d of op p osite p 0
l arity and generates a c urrent of op p osite
direc tion and inc reasing strength, whil e c oil
G, in p assing from its max imum to its neu
tral p osition generates a c urrent of dec reas
ing strength and same direc tion as before,
c auses a further shifting of the p ol es through
the sec ond q uarter of the ring. The sec ~
ond hal f- rev ol ution wil l obv iousl y be a rep e
tition of the same ac tion. By the shifting of
the p ol es of the ring A a p owerful dynamic
induc tiv e effec t on the c oil s G G is p roduc ed.
Besides the c urrents generated in the sec ond
ary c oil s by dynamo' inagnetic induc tion other
c urrents wil l be set up in the same c oil s in c on
seq uenc e of any v ariations in the intensity of
the p ol es in the ring A. This shoul d be av oided
by maintaining the intensity of the p ol es c on
stant, to ac c omp l ish whic h c are shoul d be
taken in designing and p rop ortioning the gen
erator and in distributing the c oil s in the ring
A and bal anc ing their effec t. iVhen this is
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done, the c urrents are p roduc ed by dynamo
magnetic induc tion onl y, the same resul t be
ing obtained as though the p ol es were shifted
by a c ommutator with an in?nite number of
segments. . _
The modi?c ations whic h are ap p l ic abl e to
other forms of c onv erter are in many resp ec ts
ap p l ic abl e to this. I refer more p artic ul arl y
to the form of the c ore, the rel ativ e l engths
and resistanc es of the p rimary and sec ondary
c oil s, and the arrangements for running or 0 p
j erating the same.
The new method of el ec tric al c onv ersion
whic h this system inv ol v es I hav e made the
subj ec t of another ap p l ic ation, and I do not
c l aim it therefore herein.
Without l imiting mysel f therefore to any
sp ec i?c form, what I c l aim is
1. The c ombination, with a c ore c l osed up on
itsel f, induc ing or p rimary c oil s wound thereon
and c onnec ted up in indep endent p airs or sets,
and induc ed or sec ondary c oil s wound up on
or near the p rimary c oil s, of a generator of
al ternating c urrents and indep endent c onnec
tions to the p rimary c oil s, whereby by the op
eration of the generator a p rogressiv e shifting
of the p ol es of the c ore is effec ted, as set forth
2. Thec ombination, withan annul arorsimi
l ar magnetic c ore and p rimary and sec ondary
c oil s wound thereon, of' an al ternating- c ur
rent generator hav ing induc ed or armature
c oil s c orresp onding to the p rimary c oil s, and
indep endent c irc uits c onnec ting the p rimary
c oil s with the c orresp onding c oil s of the gen
erator, as herein set forth.
3 . The c ombination, with indep endent el ec
tric transmission- c irc uits, of transformers c on
sisting of annul ar or simil ar c ores wound with
p rimary and sec ondary c oil s, the op p osite p ri
mary c oil s of eac h transformer being c onnec ted
to one of the transmission- c irc uits, an al ter
nating- c urrent generator with indep endent in
. duc ed or armature c oil s c onnec ted with the
transmission- c irc uits, whereby al ternating c ur
rents may be direc ted through the p rimary
c oil s of the transformers in the order and man
ner herein desc ribed.
NI KOLA TESLA.
Witnesses:
ROBT. H. DUNCAN,
' RoB' r. F. GAYLORD.
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