Improvements in or relating to Electric Transformers.
Year: 1898

page_text: Date o
Application, 7th June, 1898-Accepted, 30th July, 1898
COMPLETE SPECIFICATION.
Improvements in or relating to Electric Transformers.
We, JOHN JACOB BELLMAN, of No 90, King Street, in the Borough of Man-
hattan, City of New York, State of New York, United States of America,
Electrical Engineer, and CHARLES TOMLINSON RITTENHOUSE, of No 247, West
138th Street, in said Borough of Manhattan, and City of New York, Electrical
Engineer, 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:-
Our invention, relates to electric transformers and has for its objects increased
efficiency of action, simplicity of construction, accessibility of coils and ease of
removal and replacement of individual coils and other advantageous features
as will hereinafter appear According to our invention the magnetic field is
made up of plates or layers of magnetic material continuous along the path of the
magnetic flux and without air gaps or lap or butt joints therein, and therefore
the field has a minimum of magnetic resistance and requires a minimum magnetiz-
ing current According to our invention the core or portion of the field
surrounded by the electric conductor is of substantially or approximately circular
cross-section and the spool for the electric conductor is of circular cross-section
and divided or sectional so that it may be inserted within the openings about
the core in the integral plates or layers of the field, and according to our in-
vention the spool is rotated for the purpose of winding the electric conductor on
the spool and around the core and thus the operation of winding the coils is
exceedingly simple and may be rapidly performed The spool may be supported
upon wheels or rollers and may be rotated in any suitable manner for the purpose
of winding the coils Our invention includes various improvements in construc-
tion all of which will now be particularly described in connection with the
accompanying drawings forming part thereof and will be pointed out in the
claims.
In the drawing Figure 1 is a cross-section of an electric transformer embodying
our invention.
Figure 2 is a longitudinal section of the same.
Figure 3 is a cross-section of a modified construction.
Figure 4 is a longitudinal elevation of another modified construction
Figure 5 shows a form of lap joint for the parts of the divided heads or rings
of the spools
Figure 6 shows parts of a spool cylinder, enlarged, to illustrate the manner of
making the cylinder of sections and insulating the same
The field C is composed of layers of magnetic material in the form of plates
or sheets, the core being integral with the other parts and the plates having
mortises at 2 and 3 of the proper size and shape for the admission of the primary
and secondary coils, so that the magnetic flux is free to circulate through the
entire field without resistance from air gaps or breaks or joints The term
"field" is to be understood in this connection as including the circuit or circuits
DR77
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made up of magnetic material and the term core is applied to that part of such
circuit or circuits surrounded by the electric conductor
The mortises may be cut with reference to the position of each plate in the
pile of plates so that when the plates are put together the core shall be of
substantially cucular cross-section as shown in Figure 1 In some instances,
however, the plates may be cut out approximately, as shown in Figure 3, and in
such a construction or other constructions the core portions of the outer field plates
may be made sufficiently wide to permit bending them inwardly, as shown at 4,
Figure 3, thereby providing guides for the spools.
The openings or mortises may be of any desired form In the constructions
shown in Figures 1, 2 and 3, a single core is provided by two mortises 2, 3, and
a single spool is used for the electric conductor, while in the construction shown
in Figure 4 a core in two parts is provided, formed by the single mortise 2, and
two spools are used for the electric conductor
A sectional or divided spool is used interlinking with the magnetic field and
consisting of a cylinder E which may be of paper or other material and of two
or more rings or heads 7 The spool may be made up of two or more pieces
or parts so that it may be placed around the core The cylinder E may be in one
or more pieces, and if of sheet metal, it is advisable to construct it so as to
prevent the circulation of eddy curients, and to this end we interpose an insulating
strip, as particularly shown at I, Figure 6, extending longitudinally along the
cylinder. If the cylinder is made up of two or more parts, the non-insulated
joints may be formed by tongues and grooves so that the surfaces are smooth, as
particularly shown at J, Figure 6 The parts of the cylinder may be joined
together and secured or held in position in any desired manner
The heads or rings 7 may be made in sections and joined in any desired
manner, as for example a lap joint may be formed, as shown at L, Figure 5, or
they may be split open at one end and introduced around the cylinder and then
united at the opening, if desired, by laps and rivets or otherwise and secured to
the cylinder E in any desired manner, the special object being to provide a spool
sufficiently strong for winding the coils upon it and at the same time sufficiently
free to be revolved around the core
This spool is to be rotated for the purpose of building up the electric conductor
in convolutions around the core, and hence the coils can be wound upon this
spool by turning the spool by hand or by any suitable mechanism adapted thereto
The spool or cylinder may be supported upon wheels or rollers, as shown at R,
Figures 1 and 3, which act as guides, and may be then 1otated in the manner
above stated, or it may be rotated by the guide rollers or wheels themselves, which
can be revolved by any suitable power
In winding the primary and secondary coils 5 and 6, the coils may be combined
or grouped in any manner desired. We, however, prefer to wind the primary
and secondary wires in separate coils, as shown in Figures 2 and 4 These coils
when side by side around the core, are advantageously separated by rings 7,
which may also form the heads of the spools, so that if any defect arises in any
coil, the coil may be easily unwound or removed and another substituted
It may
It is of course understood that the primary coils and secondary coils may be
connected electrically in any desired manner in their respective circuits
be advantageous to use strips or bands for either primary or secondary conductors,
or for both, as illustrated in the section Figure 2, wherein the coils 6 are formed
of strips or bands It is also advantageous to fill the mortised space of the field
as completely as possible with the coils
By the present improvements it is possible to economically construct trans-
formers having distinct advantages over those hitherto made, the field having
a minimum magnetic resistance and therefore requiring a minimum magnetizing
current The coils which surround the core or cores are wound with rapidity
so as to avoid consuming unnecessary time threading the wires through the
mortised fields. This construction also affords a ready means of dividing up

page_text: the coils or helices upon the core in such a manner that the primary and secondary
coils are easy of access, and in case of defect or injury, any coil may be removed
and another substituted without disturbing the remaining coils The magnetic
leakage and resistance are reduced to a minimum
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim 18'—
1. In a transformer a ferro-magnetic field built up of integral flat plates
mortised to form the core or cores, substantially as set forth
2. In a transformer, a ferro-magnetic field built up of integial laveis of magnetic
material so mortised that when the layers are properly assembled the magnetic
field will be approximately or substantially cicular in cross-section as set forth.
3. The combination in a transformer, of a ferro-magnetic field composed of
mortised plates, a divided spool or spools interlinking with the magnetic field,
and means for causing the spool or spools to revolve, substantially as set forth
4 The combination in a transformer of a ferro-magnetic field, a spool or spools
interlinking with such field and rollers for supporting the said spool or spools
and for causing them to revolve about the core or cores of the magnetic field,
substantially as set forth.
5 The combination in a transformer of a ferro-magnetic field of integral plates
each having a mortise through it and a sectional or divided spool or spools inter-
linking with the ferro-magnetic field, and primary and secondary wires wound
upon said spool or spools by rotating said spool or spools around the core of cores
of said ferro-magnetic field, substantially as set forth
6 The combination in a transformer of a ferro-magnetic field built up of
plates, and a sectional or divided spool or spools interlinking with the ferro-
magnetic field and the winding of wire around the core or cores of said ferro-
magnetic field by the turning of said spool or spools on the core or cores,
substantially as set forth
7. An electric transformer constructed substantially as shown and described
Dated this 7th day of June 1898
BOULT & WADE,
Agents for the Applicants