Fig. The strongest points of
the field, will understood, are those be- 65
tween the projections points the polar
faces, while the weakest points lie midway
between them.
A . 371,554, (N
om
odel. If, on
the contrary, armature-core formed pro
vided with polar projections employed, it
is evident that limit soon reached at
which the iron not economically utilized,
35 being incapable following without consid
erable loss the rapid reversals polarity. machine thus constructed 75
there comparatively little that effect
which known magnetic leakage,” and
there also but slight armature reaction. SerialN
o. and
Fig.
To obviate these and other difficulties, have
devised form machine embodying the
following general features construction.)
other.
In the systems distribution electrical
energy from alternating-current generators
in present use the generators give ordinarily
from one three hundred alternations cur-
15 rent per second.nited States Patent Office. horizontal section line of
Fig. The machine these two figures is
one which the armature-conductor and the roo
field-coil are stationary while the field-mag
net core revolves. Between the faces formed mount
or support the armature coil coils and pro
vide either for rotating the field-magnet 55
the armature, both, and arrange the said
armature-coil conductor that will be
symmetrically disposed with respect the
field—that say, that when one portion
of the conductor passing through the 60
strongest portion the field the other por
tion, which forms the return for the former,
is passing through the weakest points or
parts the field. armature without polar pro
jections used, not easy obtain the
necessary strength field, mainly conse
quence the comparatively great leakage of
30 the lines force from pole pole. 95
Figure vertical central section the
machine, taken lines Fig. 447,921, dated March .
NIKOLA TESLA, NEW TORE, Y.
4 provide field-magnet core made of
two independent parts formed with grooves
for the reception one more energizing-
coils. vertical central
section amaehineembodyingtliesame plan
of construction, but having stationary field-
.
SPECIFICATION forming part Letters :
ApplicationfiledN
ovem
ber15,1890
To all whom concern:
Be known that Nikola Tesla, sub
ject the Emperor Austria,from Smiljan,
Lika, border country Austria-Hungary, re-
S siding New York, the county and State
of New York, have invented certain new and
useful Improvements Alternating-Current
Machines, which the following specifi
cation, reference being had the aecompa-
10 nying drawings. The polar faces of
the coreofthe field are not smooth,but formed
50 with great many projections serrations,
the points which one side polar face
are preferably exactly opposite those the
Patent No.
).
A field-magnet, when constructed above
described, produces, when the energizing-coil 70
is traversed continuous current, field
of great strength, and one which maybe made
to vary greatly intensity points not far
ther distant from one another than the eighth
of inch. The energizing coil, coils, com
pletely surrounded the iron core, except
45 one side, where occurs the opening be
tween the polar faces the core, which open
ing made narrow the conditions of
the machine will permit. have recognized and dem
onstrated practice that great ad
vantage, many accounts, employ such
systems generators capable producing a
very much greater number alternations
20 per second—say fifteen thousand per second
or many more. produce such high rate
of alternation, necessary construct a
machine with great number poles polar
projections; but such construction, this
25 account, order efficient, rendered
difficult.
Either the armature-conductor the field-
magnet may stationary while the other ro- 3o
tates, and often desirable maintain
the conductors stationary and rotate the
field-magnet have made special modifica
tion the construction the machine for
this purpose, and with view such case 85
still further simplifying the machine and ren
dering more easy maintain operation
I arrange the armature-conductors and the
frame supports therefor support
also fixed coil coils for energizing the ro- 90
fating field-magnet, thus obviating the em
ployment all sliding contacts.
trated the two typical forms machine
above referred to.
In the accompanying drawings haveillns-
