Improvements in Electrical Transformers.
Year: 1895

page_text: Date of Application, 19th Sept., 1895
Complete Specification Left, 19th June, 1896-Accepted, 25th July, 1896
Improvem
I, ARTHUR FRANCIS BERRY, of Manor House, Ashley, Market Harborough,
n the County of Leicester, Electrical Engineer, do hereby declare the nature of
his invention to be as follows:-
My invention has reference to electrical alternate current transformers of the
kind constructed with a core built up of slit stampings through openings in which
the coils pass.
My improved core is composed of thin metal stampings of annular form which
are suitably slit or may have two slits so that the intervening portion of the
annulus can be removed to pass the stamping over the coils and be then replaced
so as to complete the annulus, the stampings being arranged with their slit portions
alternately at opposite sides of the coils or otherwise so that slits in one shall not
be opposite slits in the adjacent stampings. To allow for expansion I build the
core in sections or lengths each composed of a suitable number of stampings, and
between one division or length and another I provide springs adapted to allow for
expansion due to heating of the metal composing the so divided sections or lengths
as well as to provide between the said sections or lengths spaces for passage of air.
Cores so built up may be constructed with stampings of other forms than annular
but the latter are preferable.
By my invention ventilation is facilitated, a relatively larger radiating surface
than heretofore usual is provided together with a uniform distance for the heat to
travel in order to reach such surface, the liability to eddy currents is obviated or
reduced, and provision is made for expansion of the core without consequent undue
pressure upon its component stampings during working, and thus liability to
histeresis and eddy currents is reduced.
COMPLETE SPECIFICATION.
Improvements in Electrical Transformers.
I, ARTHUR FRANCIS BERRY, of Manor House, Ashley, Market Harborough,
in the County of Leicester, 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 :-
My invention has reference to improvements in electrical alternate current
transformers of the kind constructed with a core built up of slit stampings through
openings in which the coils pass, as I shall now proceed to explain with the aid of
the accompanying drawings, wherein Fig. 1 is a plan and Fig. 2 a cross section
showing an electrical alternate current transformer having a core constructed
anding to this invention.

page_text: My improved core is composed of thin metal stampings 1 of annular form which
have two slits 2 and 2 so that the intervening portion 3 of the annulus can be
removed to pass the stamping 1 over the coils 4 and be then replaced so as to
complete the annulus, the stamping being arranged with their slit portions alter-
nately at opposite sides of the coils 4 or otherwise so that slits in one shall not be
opposite slits in the adjacent stampings. Instead of the two slits 2, and 2*, each
stamping may be provided with a single slit 2, the portion 3 being turned back
whilst putting the stamping upon the coils. To allow for expansion, I build the
core in sections or lengths 5 each composed of a suitable number of stampings 1,
and between one division or length 5 and another I provide springs adapted to
allow for expansion due to heating of the iron stampings composing the so divided
sections or lengths, as well as to provide between the said sections or lengths
spaces 6 for passage of air. The springs between the sections may be of various
kinds. Those shown at 7 are in the form of dished annular plates encircling the
coils 4 and arranged with their edges together, the edges being united if desired;
or coiled metal springs encircling the coils 4, or other springs may be substituted
for the springs 7; or springs may be formed by suitably bulging out the stampings
located at adjacent ends of the sections or lengths 5 so that they touch each other
as shown at 7° in Fig. 1. Cores built up in the manner described may be
constructed with stampings of other forms than annular, but the latter are
preferable.
By my invention ventilation is facilitated, a relatively larger radiating surface
than heretofore usual is provided together with a uniform distance for the heat to
travel in order to reach such surface, and provision is made for expansion of the
core without consequent undue pressure upon its component stampings during
working, and thus liability to hysteresis and .eddy-currents is reduced. Each
section or length 5 is or may be enclosed in a casing of cast or wrought iron that
will serve to hold the detachable portion 3 of each annulus in place without
interfering with the ventilation or other advantages secured by my improved
construction of core.
Having now 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 electrical alternate current transformer the core of which is composed of
a number of thin metal stampings that are suitably slit to admit of their being
placed over the coils and are arranged in sections or lengths held apart by springs,
substantially as herein-described for the purposes specified.
2. In an alternate current transformer my improved core constructed and
arranged as herein before described with reference to and shown in the drawings
annexed.
Dated this 10th dor of Lu 1906