Improved Construction of Electrical Transformers.
Year: 1897

page_text: Date of Application, 8th Nov., 1897
Complete Specification Left, 10th June, 1898-Accepted, 30th July, 1898
PROVISIONAL SPECIFICATION.
Improved Construction of Electrical Transformers.
I, CHARLES BORITSCHEWSKY, of Petersburg Quarter, Kl. Prospect No. 9,
St. Petersburg, Russia, do hereby declare the nature of this invention to be as
follows:
Hitherto the cores of electrical transformers have been formed of thin sheet iron
laminae, which were cut as shewn at Figs. 1 and 2 of the accompanying drawings,
for enabling the coils to be conveniently wound thereon.
In the working of such transformers there are produced at the points of con-
nection, Foucault and other prejudicial currents which heat the core, so that a
greater expenditure of electrical energy for magnetising the core is required than
would otherwise be necessary. This extra expenditure is more particularly felt
when only a small number of lamps are in use, and when the transformer works
without a load. On the other hand, the construction of transformers with the
form of core shewn at Fig. 3 which has also been proposed, while it is subject to
a less loss of energy, is very complicated. Each sheet metal lamina must be cut
through at the end, and after being bent back as shewn, must be introduced separately
into the coil. With a core composed of a large number of laminae this work
requires a very great expenditure of time, and when repairs are required, the
laminae must be withdrawn and re-introduced in the same manner.
My present invention relates to an improved construction whereby the production
of the objectionable currents at the joints and the consequent loss of energy are
avoided.
I will describe the construction with reference to Figs. 4 to 9, in which Fig. 4
shews a plan of the core, Figs. 5 and 6 a section and elevation of a construction
with three bobbins, Figs. 7 and 8 a sectional plan and cross section of an arrange-
ment with a single bobbin, and Fig. 9 a perspective view shewing the arrangement
for winding on the wire coils.
The cores are constructed of a series of complete laminae, having no joints.
The insulating bobbin formed in two halves is fitted together directly on to the
complete core and is so supported as to be capable of being rotated freely round
the middle part of the core. For enabling the rotation of the bobbin to be readily
effected for winding the wire of the coils thereon, I provide at the lower side of
the bobbin small rollers a, as shewn at Figs. 8 and 9, on which the rims of the
bobbin rest, so that these can then be readily rotated by pulleys b and bands c
passing round the rims, as shewn at Fig. 9, without touching the iron core.
consequence of this arrangement it is rendered possible to wind the wire directly
upon the bobbin on the closed core.
In
This work requires but little expenditure of time, and is very easy, while on the
other hand there is no useless expenditure of energy in the working of the trans-
former owing to resistances due to imperfect joints of the core, as there exist no
such joints in this case.
It will be evident that upon cores of the above described construction not only a

page_text: single bobbin but several of these may be provided for polyphase currents; thus
Figs. 5 and 6 shew respectively a plan and perspective view of a construction with
three bobbins for transforming three phase currents.
ABEL & IMRAY,
Agents for the Applicant.
Improved Construction of Electrical Transformers.
I, CHARLES BORITSCHEWSKY, of Petersburg Quarter, Kl. Prospect No. 9,
St. Petersburg, Russia, 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:-
Hitherto the cores of electrical transformers have been formed of thin sheet iron
laminae, which were cut as shewn at Figs. 1 and 2 of the drawings accompanying
my Provisional Specification, for enabling the coils to be conveniently wound
thereon.
In the working of such transformers there are produced at the points of con-
nection, Foucault and other prejudicial currents which heat the core, so that a
greater expenditure of electrical energy for magnetising the core is required than
would otherwise be necessary. This extra expenditure is more particularly felt
when only a small number of lamps are in use, and when the transformer works
without a load. On the other hand, the construction of transformers with the
form of core shewn at Fig. 3 which has also been proposed, while it is subject to
a less loss of energy is very complicated. Each sheet metal lamina must be cut
through at the end, and after being bent back as shewn, must be introduced separately
into the coil. With a core composed of a large number of laminae this work
requires a very great expenditure of time, and when repairs are required, the
laminae must be withdrawn and reintroduced in the same manner.
My present invention relates to an improved construction whereby the production
of the objectionable currents at the joints and the consequent loss of energy are
avoided.
I will describe the construction with reference to Figs. 4 to 9, in which Fig. 4
shews a plan of the core, Figs. 5 and 6 a section and elevation of a construction
with three bobbins, Figs. 7 and 8 a sectional plan and cross section of an arrange-
ment with a single bobbin, and Fig. 9 a perspective view shewing the arrangement
for winding on the wire coils.
The cores are constructed of a series of complete laminae, having no joints.
The insulating bobbin formed in two halves is fitted together directly on to the
complete core and is so supported as to be capable of being rotated freely round
the middle part of the core. For enabling the rotation of the bobbin to be readily
effected for winding the wire of the coils thereon, I provide at the lower side of
the bobbin small rollers a, as shewn at Figs. 8 and 9, on which the rims of the
bobbin rest, so that these can then be readily rotated by pulleys and bands_c
passing round the rims, as shewn at Fig. 9, without touching the iron core.
consequence of this arrangement it is rendered possible to wind the wire directly
upon the bobbin on the closed core.
In
This work requires but little expenditure of time, and is very easy while on the
other hand there is no useless expenditure of energy in the working of the trans-
former owing to resistances due to imperfect joints of the core, as there exist no
such joints in this case.

page_text: It will be evident that upon cores of the above described construction not only a
single bobbin but several of these may be provided for polyphase currents; thus
Figs. 5 and 6 shew respectively a plan and perspective view of a construction with
three bobbins for transforming three phase currents.
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, I declare that what
I claim is:-
Electrical transformers wherein the cores and frames are formed of complete
undivided laminae having no joints, the bobbins for carrying the windings being
divided so as to be fitted on to the parts of the cores and frames, and the winding
on of the wires being effected by rotating the bobbins on the cores, substantially
as described.
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