Improvements in Conductors for Electrical Machinery, and in Dynamo Electric Machines, Motors, and other Electrical Apparatus.
Year: 1896

page_text: Date of Application, 16th Dec., 1897-Accepted, 12th Mar., 1898
COMPLETE SPECIFICATION.
Improvements in Conductors for Electrical Machinery, and in
Dynamo Electric Machines, Motors, and other Electrical Apparatus.
I, JOHN MILLIS, of 1732, Twentieth Street, N.W., in the City of Washington,
District of Columbia, United States of America, Captain in the United States Army,
a citizen of the United States, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:―
This invention relates to an improved form of electric conductor and its applica-
tion to the art of generating, transforming, transmitting and utilizing electricity in
the construction of the general class of machines, instruments and apparatus whose
action depend upon electro-magnetic induction either alone or in connection with
dynamic effects and relative motion among the parts of the apparatus.
Some well known examples of apparatus of the character referred to are dynamo-
electric generators, electric motors, and electric transformers or converters including
induction coils.
Notwithstanding the great variety found in the design and construction of such
apparatus there are certain features and principles common to all practical forms here-
tofore constructed.
It will be found that the electrical currents are generated, transformed and utilized
in, as well as conveyed by, wires or conductors made of metal having a high degree
of electric conductivity, but which is non-magnetic, or incapable of becoming
magnetized to a sensible degree either permanently or temporarily. The metal most
generally used for these conductors is copper.
Associated with these non-inagnetic conductors will be found in apparatus hereto-
fore constructed, other parts essential to the operation of the apparatus which are
made of magnetic metal, and the metal used for this purpose is almost universally
iron or steel.
These magnetic parts often forin in part the frame work of the apparatus and
the mechanical connections and supports for other parts, but otherwise they
perform magnetic functions only.
The electrical conductors of apparatus of usual construction are comprised in the
armature coils and field magnet coils of dynamo generators and motors, the primary
and secondary coils of transformers, the coils of electro-magnets, etc.
The magnetic parts take the various forms of armatures, armature and field
magnet cases, yokes, pole pieces, cores of transformers and induction coils, and
the like.
Aside from their mechanical functions these parts serve only to afford paths for
and to direct and apply the magnetic inductive effects commonly referred to as
the "lines of force."
The magnetic parts are not usually designed to convey currents of electricity;
on the contrary, special construction of such parts, in alternating current apparatus
particularly is generally resorted to, in order to prevent the generation in them of
"eddy" or "Foucault" currents. Such currents would result in heating of the

page_text: parts and in loss of efficiency, or they might even render the apparatus entirely
inoperative.
The magnetic parts are generally massive, they add greatly to the weight of the
apparatus, and are frequently of costly construction. They are also the source of a
certain loss of efficiency, particularly in alternating current apparatus, on account of
the magnetic "hysteresis" of the metal.
The invention herein to be described consists in a conductor designed to be used
for the active parts of the general class of electro-magnetic or magneto-electric
apparatus referred to, which conductor will do away, either entirely or to a large
extent, with the necessity of using separate parts. performing the functions of
magnetic elements and not conveying useful currents.
The improved conductor is made in whole or in part of a material which is
both magnetic or capable of being magnetized, and an electrical conductor. Such
material is preferably iron or steel, and for most applications it should be soft nearly
pure iron or low steel combining a high degree of magnetic permeability and
electrical conductivity.
The desired results are produced by the direct electro-magnetic inductive actions
between such conductors or between the different parts of one such conductor.
These inductive actions alone produce the results, as in static apparatus like
converters and induction coils, or the inductive actions in connection with relative
motion of parts are used, as in dynamo generators, motors, and rotary
transformers.
In order to more clearly describe the nature of my invention, reference is had to
the accompanying drawings, wherein similar parts are designated by similar letters
throughout the several views.
Fig. 1 represents a solid soft iron conductor, showing the direction of the magnetic
stresses.
Fig. 2 represents an end view of a conductor composed of concentric rings or
tubes of soft iron.
Fig. 3 represents a conductor such as shown in Fig. 2, divided in halves.
Fig. 4 represents a plurality of the conductors shown in Fig. 3, illustrating the
mutual inductive effect.
Fig. 5 represents a plurality of conductors constructed according to my improved
principle, further illustrating the inductive effect between neighboring conductors.
Fig. 6 represents an end view of another form of conductor constructed according
to my improved principle, and
Fig. 7 represents still another form of the same.
Fig. 8 represents a central vertical section of a static transformer constructed with
my improved conductors, and
Fig. 9 represents a top plan view of the same with a portion of the top conductor
broken away.
Fig. 10 represents a vertical section along the line 10-10, in Fig. 11, and looking
in the direction of the arrow, and showing the application of my improved conductor
to the construction of dynamo-electric machines or motors.
Fig. 11 represents a side elevation of the same machine.
Fig. 12 represents a development of a part of the armature coils of the machine
shown in Figs. 10 and 11, and Fig. 13 shows an arrangement of the coils when used
in the generation of two-phase currents.
Fig. 13 shows the arrangement of the conductors for a two-phase motor.
Fig. 14 represents a form of conductor similar to those shown in Figs. 12 and 13
except that the folds are wider apart than in those shown above.
Fig. 15 represents an enlarged perspective view of a part of the conductor shown
in Fig. 12, showing how the conductor is enclosed on three sides by a continuous
magnetic metal envelope or trough.
Fig. 16. represents a conductor in which the different laminæ are connected in
multiple.
Fig. 17 represents a conductor in which the laminæ are in series, and

page_text: Fig. 18 represents lamine of the conductor connected in multiple series.
Fig. 19 represents diagrammatically a method of connecting adjacent conductors
different from that shown in Fig. 12, and
Fig. 20 is an enlarged perspective view, showing a form of connector for the ends
of the adjacent conductors.
Fig. 21 is a sectional view showing a means of attaching the conductors of the
machine shown in Figs. 10 and 11 to the supporting rings, when the rings are not
made of magnetic material.
Fig. 22 is a similar view representing a way of accomplishing the same result when
the rings are made of magnetic metal.
Fig. 23 represents a conductor composed of laminations of different metals.
In Fig. 1, A represents a soft iron rod. Supposing a current of electricity to be
passed through this rod in the direction of its length as towards the bottom of the
figure, for example. In accordance with well established laws the metal of the rod
will be polarized or magnetized while the current is passing, and, the direction of this
magnetization will be represented by the circumferences of circles a whose planes are
perpendicular to the axis of the rod, and which have their centers on that axis.
'The direction and degree or intensity of the magnetization of magnetic stress will
depend upon, the direction and strength of the current which produces the
magnetization. If, therefore, the current be varied in strength a corresponding
change will follow in the magnetic stress, and if the current be reversed in direction
the direction of the magnetic stress will be reversed.
Conversely, if the transverse magnetization or magnetic stress represented by
lines be varied in strength or direction, corresponding changes in the current flowing
along the rod will result.
The transverse magnetic stress in the rod resulting from the passing current
produces magnetic stresses external to the rod, and the direction of these external
stresses may be represented by the circumferences of circles a¹¹ whose planes are
perpendicular to the axis of the rod, and whose centers lie in that axis.
These external inductive magnetic effects are illustrated by the well known
experiment of iron filings sprinkled on the card A. These filings tend to arrange
themselves in circles a' when a current is passing, which circles are ordinarily called
"lines of force."
The well known inductive effects which take place between parallel electric
conductors are explained by these lines of force, as are also the relative motions of
such conductors when they are conveying currents and are not relatively fixed in
position.
The laws of inductive actions between such conductors, and the forces of attraction
and repulsion developed are well known principles of the science of electricity and
magnetism.
As explained above, the current in conductor A, produces magnetic stresses which
are perpendicular to the axis of the conductor but do not intersect the axis.
Similarly, a change in the magnetic stress at any point in the conductor, regarded as
a cause, tends to produce a current around this point, and in a plane perpendicular
to the direction of the magnetic stress. As a result of this, when the current is
rapidly changing in strength and direction, as when an alternating current is sent
through A, the current in the interior of the conductor is very much reduced by
mutual interference, and the current, therefore, passes principally on the outer
portions. This is commonly known as the "skin effect."
Now let the iron rod be split up by surfaces of cylindrical shape and parallel to
the axis, so that instead of a solid rod, we have one made up of a number of thin
concentric tubes or shells, and let these tubes or shells be separated by layers or
insulating material like paraffined paper.
An end view of such a conductor is shown in Fig. 2. B is the conductor composed
of concentric tubes made of soft iron or steel b, with intervening layers of insulation b¹
as shown.
By this construction the continuity of the metal in the direction of the length of

page_text: the conductor, as well as in circular directions around the axis, is preserved. With
the same area of cross sections of metal the electric conductivity for steady currents
is as great as is a solid conductor, and the magnetization or transverse magnetic
stresses resulting from a current through the conductor have also uninterrupted paths
through the metal in circular directions around the axis.
The continuity of the metal in all directions intersecting the axis is, however,
interrupted at numerous points by the insulation. By making the layers of metal
sufficiently thin the possibility of "eddy" currents or current actions, in directions
intersecting the axis may be practically removed.
Now, let the conductor be split lengthwise into two similar parts B' and B², Fig. 3,
and let these parts be separated a short distance, remaining parallel, with a thin
layer of insulation, or a space, between them.
Under these circumstances the conditions are highly favorable for the various
electro-magnetic inductive actions and the dynamic effects which take place between
parallel conductors in accordance with the well known laws of electro-magnetic
induction. The laminations of the conductors and the intervening layers of
insulation cut off detrimental cross current actions or eddy current effects, while the
"lines of force" or lines of electro-magnetic induction have free paths through iron
which enable them to act with the greatest facility to produce the desired results.
The directions of these lines are indicated in Fig. 3 by the dotted lines, by which it
will be seen that the magnetic stresses are transmitted throughout by continuous
iron, except over the small gap on thin layer of insulation between the conductors.
If the conductors B1 and B2 are fixed in relative position and each forms part of a
completed electrical circuit, an alternating or inconstant current sent through one
will induce a corresponding current in the other. If the conductors can move
relatively to each other, and currents in opposite directions are sent through both,
they will repel each other; if currents in similar directions are sent through them,
they will attract each other. If a continuous current be sent through one and the
other he moved relatively to the first, a current will be generated in the second one
according to the general law. Fig. 4 shows conductors B B B capable of motion
relative to each other in accordance with the above.
Instead of the circular form, or semi-circular form for the section of the conductors,
it is evident that many other forms may be made, the principles of action remaining
the same, and also that any number of conductors may be combined upon principles
already explained for two.
Thus, in Fig. 5 six conductors are shown placed parallel to each other, and when
carrying a current the inductive actions between them will be as above described.
For instance, if e, ƒ and g are connected in multiple to form part of one circuit,
and h, and are similarly conuected to form part of another circuit, an alternating
current sent through one set will generate an alternating current in the other.
Again, if one set, h, i, k, is made movable with respect to the other set e, f, g,
relative motion will take place as indicated, the movable conductors passing to the
position shown in dotted lines when the alternating current is sent through
set e, f, g.
Or currents may be generated by the application of external power to cause such
relative movement to take place.
Some practical applications of this invention to electrical apparatus will now be
described and illustrated.
Referring to Figs. 8 and 9, the transformer is made up of a number of flat spiral
coils of soft iron ribbon C and D. In coils D the ribbon is simply coiled up with
insulating material to prevent contact between contiguous turns. Coils C are formed
by first making compound conductors of the desired number of ribbons, similar to
those in coils D with insulations between the ribbons; this compound conductor is
then coiled up-as shown. The spiral for the outside of the converter may have an
additional U-shaped strip of iron ribbon placed over it to better utilize the electro-
magnetic inductive effects, or in other words to reduce the magnetic leakage, as

page_text: shown in Fig. 6, or thin sheet disks H may be put over the top and bottom as shown
for the same purpose, with radial cuts to interrupt useless currents.
The coils are so laid or placed that the connection will come alternately inside and
outside of the converter for greater convenience, as shown in Fig. 8.
If used, as converters are commonly used, for transformning currents of high
potential to those of lower potential, coils D would constitute the primary circuit
with terminals d, l, and coils C would be the secondary circuit with terminals c, c',
the heavy dotted lines representing the secondary connections and the light dotted
lines the primary.
To better insure the perfection of the insulation, sheets and strips of insulating
material like mica may be placed between these coils as at co and coo. It is obvious that
these transformer coils may be placed in oil insulation as is frequently done with
transformers.
Connections for the terminals, safety cut-outs, and other accessories are, of course,
to be provided, and the coils are to be properly secured in fixed relative positions.
The terminals of the various coils may be brought to suitable terminal connectors
accessible for adjustment, so that the converter may be altered for various effects
without disturbing its interior construction. Besides single converters, those
designed for polyphase currents of any desired characteristic may be constructed on
the same principle.
Figs. 10 and 11 show the application of this form of conductor to the construction
of a dynamo generator, or an electric motor.
The conductors X and Y are made of iron or soft steel strips with insulation
between the strips as already described. The conductors X are secured to the
rings M concentrically supported by spider arms N on the shaft W; this shaft is
supported in bearings mounted on supports R, which are secured to a suitable base S.
The shaft and its attachments including the conductors X are free to turn about the
axis with the shaft. The rings L, I support the conductor Y, and these latter rings
are rigidly secured by uprights P, and braces P in position concentric with rings M
and in planes parallel to the planes of said rings. Conductors Y are secured to the
inner surfaces of rings L. Rings L. and M may be made of insulating material like
"fibre" or of metal. If made of metal the conductors should be secured to them
without electrical connection, as by interposition of insulating material, as shown in
Fig. 22.
The terminals x-x of the conductor X (see Fig. 12) may be connected to the
collector rings V in any convenient manner, as for example, the conductors from the
terminals xx may be carried down one of the spider arms and thence through a
hollow in the shaft W to the rings as.is usually done in dynamo construction. The
conductors T from the terminals of the conductors Y are carried to a switch T¹ on the
upright R.
Fig. 12 represents a development of the conductor X carried in the rings M showing
the terminals xx¹ of the said conductor. As the conductors X and Y are similar
and the method of securing them to the rings is the same, a description of one will
suffice for both.
The conductor X as shown is folded upon itself and secured to the rings M by
means of screws or bolts H. If the rings M are non-conductors of electricity the
method for securing them as shown in Fig. 21 may be adopted, or if of conducting
material, the arrangement shown in Fig. 22 may be employed, where H¹ is a bolt
passing through the conductor and ring and insulated from the latter as at m.
obvious that any convenient and practical means may be employed for securing the
conductors to their supports. The conductors may be folded as shown in Fig. 14,
leaving a greater space between parallel parts of the conductor. In order to prevent
leakage of the magnetic lines on the sides of the conductor when the lines will not be
available, the strips of the conductor may be covered on three sides by the outer
troughs of thin iron K as shown most clearly in Figs. 6 and 15, or they may have a
thin flat iron backing K¹ as shown in Fig. 7. When thus made, the main part of the
conductor may be made continuous and folded back and forth, as in Fig. 12, the

page_text: covering piece being cut out, or otherwise formed and then placed on the conductor
and secured thereto. There are obviously many ways of connecting the conductors
for different purposes; for example, the different lamine or strips may be connected
in multiple as shown in Fig. 16, or in series, as in Fig. 17, or in multiple series, as
in Fig. 18. Instead of folding the conductors upon themselves, they may be made in
separate pieces as shown in Fig. 19 and their ends connected alternately, as shown,
by suitable conductors. If the adjacent conductors are very close together, the means
shown in Fig. 20 may be used, when.Q represents a copper end piece in electrical
connection with the strips of the conductors.
Returning now to the operation of the machine shown in Figs. 10 and 11, let a
continuous current from some external source. be sent through one set of the
conductors as Y by conductors led from the external source to the terminals of
that conductor. If the shaft be now revolved, and with it the attached rings and
conductors X, an alternating current will be generated in these conductors which may
be led off on the brushes Z and utilized. The apparatus is, therefore, a separately
excited alternating current generator. If two such machines are placed end to end,
shafts in line and rigidly connected so that the conductors X of one machine have
the proper angular advance in relation to the corresponding conductors of the other,
while the conductors Y of both machines are in line the combination will form in
effect, a separately excited two-phase generator. Similarly, a two-phase generator
may be constructed by using in the same apparatus two sets of conductors X X in
Fig. 13, and one set of conductors Y, which latter are made long enough to extend
over both X and X. Upon the same principle by using three sets of conductors X a
three-phase generator is made. Obviously, a machine of any number and combina-
tions of phases may be built by extending the principles of construction above
described. If used as a two-phase motor, the conductor X, Fig. 13, would be given
angular advancement equal to one half the thickness of Xor X. By placing
commutators on the shaft to properly direct the currents the machine becomes a
continuous current generator or motor. Thus, by means of a commutator, a con-
tinuous current applied to the terminals Z is made to pass in alternate directions
through the conductor X, and conductor Y being short-circuited, the machine runs
as a motor.
Similarly, if coils are excited by a continuous current, the alternating current
generated in conductor X may by means of a commutator attached to the shaft, be
rectified or all the pulsations given the same direction.
While the construction shown in Figs. 10 and 11 with the magnetic conductors
secured to cylindrical surfaces and in a position parallel to the axis of revolution is
practical and simple, many variations of this form are entirely practicable. The
conductors may be inclined to the axis at any desired angle instead of being
parallel to it, there may be more than two concentric cylinders and sets of conductors,
or the conductors may be arranged radially about the shaft in planes perpendicular
to it, etc.
In general, the conductor is made of thin strips of wrought iron or low steel which
are preferably rolled for the purpose, but which may be cut from sheet metal.
These strips are given such width and shape and are assembled in such manner as to
give the conductor the required construction and cross section. It is in general
desirable to make the insulation between these strips as thin as practicable. The
insulation may consist of a coating of varnish or enamel on the strips, or material
like mica or paraffined paper may be used. The strips are held together by external
wrapping by clamps, by rivets or bolts, or any other suitable means. The conductor
may not be made entirely of magnetic metal, but strips of other metal like copper
may be combined with the iron strips to reduce the electric resistance or for other
reasons. Such a conductor made of alternate strips of copper and iron with an
U-shaped envelope made of iron is shown in Fig. 23, in which Q is the iron and Q
is the copper.
While plain flat strips of uniform width and thickness for a given conductor will
ordinarily be used as far as practicable to simplify the construction, the invention is

page_text: not limited to these conditions. The conductor may be divided into separate lengths
connected by lengths of conductors made of copper or other metal, the form of cross
sections of the conductor may be varied at different points in the same conductor,
or the position of the cross section at one point may be relatively different from that
at another, as when the conductor is twisted about its longitudinal axis, etc.
Among the advantages gained by the applications of this conductor, are greater
simplicity and economy in construction, and reduction in weight of apparatus for
a given output. The losses due to hysteresis which occur in some forms of apparatus
as now constructed, are also reduced.
A great variety of applications other than those mentioned or indicated will
suggest themselves to electricians, such as in telegraph apparatus, electric bells, and
signals, regulating devices for electric light and power machinery, mensuring and
test instruments, etc. In fact, the applications of this device extend to the larger
part of the appliances that involve directly or indirectly the principles and laws of
electro-magnetic induction.
Having thus particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. An electric conductor made of thin strips or laminations of material which is
both a conductor of electricity and also capable of being affected by, and of
readily transmitting magnetic force or influence, and having the lamina separated
by insulating material.
2. An electric conductor composed of strips or lamine of iron or soft steel
separated by an insulating substance, and so arranged as to afford uninterrupted.
paths for electric currents only in directions along the length of the conductor,
while the transverse magnetic stresses are afforded nearly or quite free paths through
the metal of the conductors.
3. An electric conductor composed of laminations of material which is both
a conductor or electricity and also capable of being affected by, and of readily
transmitting, magnetic force or influence, an insulating substance separating the
lamina of said conductor and the said lamine so disposed as to afford uninterrupted
paths for electric currents only in directions along the length of the conductor,
while the transverse magnetic stresses are afforded nearly or quite free paths through
the metal of the conductor.
4. An electric conductor constructed in whole or in part of magnetic material,
properly insulated and designed for use as the active parts of the general class of
electro-magnetic or magneto-electric machines, instruments and apparatus, in which
the desired results are produced by the direct electro-magnetic inductive effects.
between different conductors or between different parts of the same conductor, either
with or without dynamic action and relative motion of the conductors or parts of
conductor.
5. A dynamo-electric machine having an armature whose coils are both conductors
of the electric current and magnetic in their action, and the field of said machine
being composed of coils similar to the armature coils.
6. In a dynamo-electric machine or motor, the combination with a movable con-
ductor composed of laminations of material which is both a conductor of electricity
and magnetic in its action, and having the lamine of said conductor separated from
each other by insulating materia!; of a stationary conductor of similar structure
mounted near and parallel or nearly so to said movable conductor, and the laminated
conductor so arranged as to afford uninterrupted paths for the electric currents only
in directions along their lengths, while the transverse magnetic stresses are afforded
nearly or quite free paths through the metal of each conductor.
7. In a dynamo-electric machine or motor, the combination with a plurality of
novable conductors, composed of laminations of material which is both a conductor
of electricity and magnetic in its action, and having the laminae of said conductor
separated from each other by insulating material, of a plurality of stationary

page_text: conductors of similar structure mounted near and parallel or nearly so to said movable
conductors, and the laminæ of all the said conductors so arranged as to afford
uninterrupted paths for electric currents only in directions along the lengths of the
conductors while the transverse magnetic stresses are afforded nearly or quite free
paths through the metal of the conductors.
8. In a dynamo-electric machine, the combination with a plurality of conductors
composed of laminations of material which is both a conductor of electricity and mag-
netic in its action, and the lamina of said conductor separated by insulating material;
a shaft and means for securing said conductors at intervals from each to and around
the said shaft; a frame having bearings in which said shaft is journalled; a plurality of
stationary conductors of similar structure secured in a frame and enclosing and
concentric with the movable conductor; and the laminæ of all the said electric
currents only in directions along the lengths of the conductors, while the transverse
magnetic stresses are afforded nearly or quite as free paths through the metal of the
conductors.
9. Electrical apparatus dependent upon the direct electro-magnetic inductive
effects of its active parts, in which the parts between which said inductive effects
take place are all conductors of electricity and magnetic in their action.
Dated the 16th day of December 1897
PHILIP M. JUSTICE,
Chartered Patent Agent, London, for the Applicant.