Improvements in Dynamo Electric Machines.
Year: 1895

page_text: Date of Application, 9th Feb., 1895--Accepted, 30th Mar.,
1895
COMPLETE SPECIFICATION.
Improvements in Dynamo Electric Machines.
I, JAMES DEVONSHIRE, Secretary of The British Thonison-Houston Limited of
38 Parliament Street, Westminster in the County of Westminster (a communication
to me from abroad by Charles P. Steinmetz of Schenectady, County of Schenectady
State of New York United States of America) do hereby declare the nature of
this invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
This invention relates to improvements in dynamo electric machines, and more
particularly to those machines in which cross or end connections over-lap at the
ends of the armature or field. Such over-lapping exists in direct current-alternating
and polyphase machines in which there is more than one tooth per pair of poles.
In all machines of the above character, it has been usual to so construct the
winding that at every point of circumference the coils overlap one another at the
end of the armature or field. This is a serious objection, as it renders the coils
difficult of removal for repairs, and makes it impossible to divide the magnetic
structure without removing some or all of the coils.
This invention consists in arranging the coils in separate sets of sections, whose
combined effect is the same as that of the continuously overlapping coils now used,
but whose end portions or cross-connections while over-lapping in each set, do not
overlap those of other sets. This enables each set to be removed independently of
and without disturbing the others, and also enables the magnetic structure to be
divided up into two or more separable parts.
One advantage of this is that it renders it possible to make a three-phase
induction motor, which is eminently suited for use as an electric railway motor, the
field structure being divided say, along a horizontal plane, in like manner to the
present direct current railway motors. The advantages of such a construction are,
that it permits ready inspection and repair of the motor parts, including the
armature, while the machine as a whole remains in place on the truck.
in the accompanying drawings
Figure 1 is a diagrammatic-representation of the armature winding of a three-
phase machine, either a generator or a synchronous motor.
Figure 2 is a similar diagram, showing the winding as applied to a monocyclic
machine.
Figure 3 is an end elevation of a three-phase induction railway motor, having its
field winding arranged according to this invention.
Figure 4 shows the punching which may be used in constructing the field of such
a motor.
Figures 5 and 6 show the application of the invention to direct current-machines
respectively of 4 and 8 poles.
Referring to Figure 1; 1, 2, 3, 4 etc. represent field poles of a three-phase twelve
pole generator, of which A may represent the armature. The radial lines drawn
on the armature represent, according to usage, portions of the wire that sweep
across the field, and in which the electro-motive-force is generated, while the
diagonal lines at the end represent the cross or end connections. The winding
consists of coils a b c etc. and the heavy black lines representing the single coil are
supposed to represent a number of turns constituting that coil, the light lines at
the end representing the connections between successive coils. It will be seen

page_text: that the coils are substantially similar in size and shape, each having a breadth
about equal to the pitch or distance between poles, and that they are connected
around in consecutive order.
It will also be seen that there are nine coils for each pair of poles, and being a
three-phase machine, there are three coils for each phase per pair of poles. In
polyphase machines of this character, it has been usual to wind the coils in a
regular succession around the complete circumference of the machine. The coils
in, say a three-phase machine, being divided into three series, each series having
a part recurring at regular intervals around the machine, and the three series over-
lapping continuously around the machine so that at no portion of the circumference
was the magnetic core free from over-lapping parts of the winding, and the whole
structure was so bound together that it was impossible to separate the magnetic
structure without disturbing the winding.
In accordance with this invention the winding is divided into separate
groups CD etc.
It will be seen that while the winding in each group over-laps at
the end or cross-connection, they do not over-lap, and are entirely free from the
windings of other groups. Each set or section CD of coils extends over a range
or circumferential portion of the armature, corresponding to one pair of adjacent
poles, and with this construction there would be as many sets as there are pairs of
poles. It is then possible to divide the magnetic structure into as many parts as
there are pairs of poles.
The machine, if a generator may be supposed to be delivering separate three-
phase currents to separate circuits from each set of coils or the separate sets of
coils may be connected together in series or parallel by appropriate connections
which may be readily separable in case it is desired to remove any one of the coils
or divide the magnetic structure of the armature. If it is used as a motor similar
connections would be made.
In Figure 2, C D etc. represent as before, separate groups of coils, similarly
disposed with reference to the successive pairs of poles. This machine is, however
supposed to be a single phase machine having main terminals X Y, X¹ Y' etc. for
each set of coils, and intermediate terminals Z Z etc. to about the middle portion
of each coil. Such a machine can be connected to feed a number of separate
alternating circuits, and provide an intermediate or out of phase main for each
circuit in accordance with what is known as the monocyclic system. By properly
connecting up these sets of coils CD, they can be made to feed a single circuit
in multiple. They may also be connected in series with a single circuit, by
connecting the end of each set to the beginning of the next and leading out
terminals from the first and last ends of the end sets, and making an intermediate
connection from the intermediate set to a supplementary out of phase main. By
omitting the intermediate connections altogether the machine becomes a single
phase machine pure and simple, and while this invention is of special importance
in connection with polyphase machines, yet so far as is known to me, it is new to
make a single phase lap winding, which is divided up into entirely separable sets,
each set over-lapping only within itself, and not overlapping with any other set.
I consider this invention as extending to single phase machines.
In Figure 3, H represents the axle, G the axle gear and I the pinion of a three-
phase induction motor, having a closed circuited armature K and a field L. This
field structure consists of laminations or punchings 7 clamped and held in an outer
frame M. These punchings may be made as indicated in Figure 4, consisting of
a long and short portion, together forming a half circle. The punchings have
dove-tail recesses on their outside, which fit in with dovetail projections on the
field frame, and the long and short punchings are placed alternately so as to break
joint. The punchings on the inner side are provided with slots to receive the
winding which is divided up into sections CD. Thus in the three phase twelve
pole motor shown there would be three sections above the centre-line of the motor
and three below it, and as the sections immediately above the middle line of the
motor do not over-lap the sections immediately below the middle, it becomes

page_text: possible to divide the motor in two along this line as is usual with direct current
railway motors. The field frame is therefore divided along the line T, the two
parts being hinged together at p, and held together by removable fastenings in the
usual manner. The field punchings are also so arranged that a split or division
occurs along this line.
The motor is shewn as having a short circuited revolving member and a
stationary inducing field, but it is obvious that the relation might be reversed,
and a three-phase current be led to the revolving member, in which case the field
would be closed circuited on itself, but would have a similar arrangement to that
above shown.
This invention is also applicable to direct current machines as shown in Figure 5
wherein 1. 2. 3. 4. represent field poles of a 4-pole direct-current machine.
A represents the armature carrying coils or bars, having E.M.F. producing portions a
and cross or end connections a¹. As usual, there are a larger number of bars or coils,
than there are pairs of poles, and the bars or wires under one pole are connected
across to bars or wires under a pole of opposite sign-the successive bars or wires
being connected in consecutive order. Now by the usual method of winding this
cross connection is continuous around the machine, proceeding from one pole to
another, until the circuit of the armature is made. It has been found however,
that in a direct-current machine, of two or more pairs of holes, the coils may be
divided into sections or sets, one for each pair of poles, and the cross connections
of each set may be independent of and free from over-lapping with the cross
connections of the other sets. Thus in this 4-pole machine there are two sections
of coils C and D, which do not over-lap one another, but are connected by
connection at i which may be made easily separable and by cross connections on
the commutator. Each of these sections corresponds to a single pair of poles, and
it will be seen that in a multiphase machine, we can get as many sections,
independent of one another, as far as overlapping cross connections on the
armature is concerned, as there are pairs of poles. And we therefore correspondingly
divide the magnetic structure of the armature into two or more sections, in the
same way as above indicated for alternating machines. With 4 poles, however,
as shown in Figure 5, it is seen that the commutator is not separable, and to get
the condition of complete separability of commutator, as well as armature winding,
it is necessary to have a multiple of 4 poles-for example 8-as shewn in Figure 6.
Here the parts are lettered as in Figure 5, but are duplicated on the two sides of
the machine, the sections C and D on one side and the sections C¹ and D' on the
other side, with their corresponding parts of the commutator, constitute two
complete and separable portions of the machine, so that the latter could be split
along the line F, through the magnetic core, commutator and all without disturbing
any connections.
It will be seen therefore that this invention, broadly, covers the division of the
winding into sections or units, each unit being, so to speak, complete in itself and
independent of other units. This independence may be only partial, and imply
only that the coils do not over-lap, or it may be entire dependence, the coils being
mechanically free from one another, and if desired electrically separate.
While the invention is described in connection with dynamo electric machines,
it is obviously applicable to any electro-magnet structure, embodying the same
general arrangement of parts and having portions of the winding over-lapping.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In a dynamo electric machine, a winding consisting of two or more sets of
coils, each set over-lapping within itself, but not over-lapping with other sets.
2. In a dynamo electric machine, a winding consisting of a number of sets of
coils corresponding to the number of pairs of poles, each set over-lapping within
itself, but not over-lapping with other sets.

page_text: 3. In a dynamo electric machine, a winding consisting of two or more sets of
coils, corresponding to the number of pairs of poles-each coil having a breadth
substantially equal to the polar distance, and the coils in a set over-lapping each
other, but not over-lapping coils of other sets.
4. In a polyphase dynamo electric machine, the combination of a circular
magnetic structure, coils arranged around said structure and associated in sets, the
coils of each set over-lapping one another, but not over-lapping coils of other
sets.
5. In a polyphase dynamo electric machine, the combination with the armature
and field core of coils arranged in sets on said core-each coil having a breadth
substantially equal to the distance between the poles developed in said core, and
the coils of each set over-lapping each other, but not over-lapping coils of
other sets.
6. In a dynamo electric machine, the combination with a magnetic core-separable
into two or more parts, of a winding on said core, consisting of coils over-lapping one
another the coils on one of said separable parts not over-lapping with coils on the
other part or parts.
7. In a dynamo electric machine, the combination with a magnetic core,
separable into two or more parts, of a winding on said core, having its coils
overlapping one another, on each separable part, but not over-lapping coils on the
other part or parts.
8. A polyphase dynamo electric machine or motor, having its armature or field
core divided into two or more separable parts, with coils on each part over-lapping
one another, but not over-lapping coils on other parts.
9. A polyphase motor, having an inner revolving member, and an outer
stationary member, the outer member having its core divided into two parts, and
having coils on each part over-lapping one another, but not over-lapping coils on
the other part.
Dated this 8th day of February 1895.