Improvements in Electric Converters.
Year: 1891

page_text: Date of Application, 1st Apr., 1891
Complete Specification Left, 5th May, 1891-Accepted, 6th June, 1891
PROVISIONAL SPECIFICATION.
[Communicated from abroad by MOSES GERRISH FARMER, of Eliot, in the
County of York and State of Maine, U.S.A., Electrical Engineer.]
Improvements in Electric Converters.
I, REGINALD WALTER BARKER, of Monument Chambers, King William
Street, London, Middlesex, Patent Agent, do hereby declare the nature of
said invention for IMPROVEMENTS IN ELECTRIC CONVERTERS, to be as
follows:-
My invention has reference to improvements in electrical converters or in-
ductoriums, for converting, by induction, currents of a given tension into currents
of a different tension, and my improvements have special reference to the con-
struction of the core of the converter and to the magnetic shield for confining the
magnetic lines of force upon the inducting and induced coils.
In apparatus of this kind, the core is frequently built up of lamine of iron,
separated from each other by thin layers of insulating material, such as paper,
card-board &c., and in many cases the lamina of magnetic material are placed
directly in contact with each other, without the intervention of insulating
material. In both constructions there is this defect, that the assembling of the
lamine which constitute the core, is tedious and complicated and in the case where
insulating partitions between the lamina are used, the building up of the core
requires great care and nicety of manipulation. When no insulating portions are
used the rapidity of magnetization and demagnetization of the core is in a great
measure lost, so that inductoriums made with such cores are very little better than
if the cores were made of solid pieces:
By my invention, these defects are overcome, in that retain the principle of
laminating the core but in place of the insulating material for separating the
magnetic lamine, I use very thin sheets of non-magnetic metal, each of which,
together with two magnetic lamine, soldered or sweated to it, constitutes a core
element, and all these elements may be assembled to build up a core of any desired
cross-section in an expeditious and easy manner.
I have also found that the efficiency of the converter is increased when each magnetic
lamine is made either shorter than the whole length of the core, or when it is made
in two parts, which together have the length of the core but are not in direct or
solid contact, so that the core may be laminated, not only in planes parallel to its
axis, but also in planes at right angles thereto.
The magnetic shield which I provide I construct in two parts, closely fitting the
pole-pieces of the core and so shaped as to be easily mounted and dismounted.
In the construction of my improved converter core, I use a great number of thin
sheets of non-magnetic metal, shaped with a shank and a cross head formed at each
end of the shank. These non-magnetic lamina may be made of zinc, brass, copper
or other like metal and they are covered on both sides with a thin adherent film
of tin, or other easily fusible non-magnetic metal; this is done by the ordinary
process of tinning, and it is of no consequence whether in this process the edges of
the lamina are also tinned or not, except as will be hereinafter set forth.
For each laminæ of non-magnetic metal, I provide two lamina of soft iron, which
are also tinned on both sides, and are therefore, preferably cut from the ordinary
tinned sheet-iron.
Having provided a great number of these magnetic and non-magnetic laminæ,
they may be put together to form a core-element, in a variety of ways.
As has been stated above, the laminæ are tinned on each side, and when applied

page_text: to each other they are heated under pressure until the tinned surfaces in contact
become fused or sweated together.
Dated this 1st day of April 1891
COMPLETE SPECIFICATION
Improvements in Electric Converters.
1. REGINALD WALTER BARKER, of Monument Chambers, King William
Street, London, Middlesex, Patent Agent, do hereby declare the nature of my inven-
tion for IMPROVEMENTS IN ELECTRIC CONVERTERS, 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 converters, or in-
ductoriums, for converting, by induction, currents of a given tension into currents
of a different tension, and my improvements have special reference to the construc-
tion of the core of the converter and to the magnetic shield for confining the
magnetic lines of force upon the inducting and induced coils.
In apparatus of this kind, the core is frequently built up of laminæ of iron,
separated from each other by thin layers of insulating material, such as paper,
card-board, &c., and in many cases the lamina of magnetic material are placed
directly in contact with each other, without the intervention of insulating material.
In both constructions there is this defect, that the assembling of the lamina which
constitute the core, is tedious and complicated and in the case where insulating
partitions between the laminae are used, the building up of the core requires.great
care and nicety of manipulation. When no insulating portions are used the-rapidity
of magnetization and demagnetization of the core is in a great measure lost, so that
inductoriums made with such cores are very little better than if the cores were made
of solid pieces.
By my invention, these defects are overcome, in that retain the principle of
laminating the core but in place of the insulating material for separating the
magnetic laminae, I use very thin sheets of non-magnetic metal, each of which,
together with two magnetic lamina, soldered or sweated to it, constitutes a core
element, and all these elements may be assembled to build up a core of any desired
cross-section in an expeditions and easy manner.
I have also found that the efficiency of the converter is increased when each
magnetic laminae is made either shorter than the whole length of the core; or when
it is made in two parts, which together have the length of the core but are not in
direct or solid contact, so that the core may be laminated, not only in planes parallel
to its axis, but also in planes at right angles thereto.
The magnetic shield which I provide I construct in two parts, closely
fitting the pole-pieces of the core and so shaped as to be easily mounted and
dismounted. All this will more fully appear from the following detailed
description, with reference to the accompanying drawing, in which I have
shown in
Figure 1, a face view of a non-magnetic metallic lamina entering into the con-
struction of my improved converter core; in
Figure 2 a like view of a magnetic lamina;
Figures 3 and 4 edge views of one form of a core element and an assemblage of
the same respectively, in accordance with my invention;
. Figures 5 and 6 are like views of another form of a core element and of an
assemblage of the same;
Figures 7 and 8 are edge views of still another form of a core-element and an
assemblage of the same, respectively;
Figure 9 is a perspective view of one form of my improved-converter core:
Figure 10 is a perspective view of a converter or inductorium constructed in

page_text: accordance with my invention, showing a portion of the magnetic shield broken
away; and
Figure 11 is a perspective view of a cup-shaped magnetic shield.
In the construction of my improved converter core, I use a great number of thin
sheets of nou-magnetic metal, shaped as shown in Figure 1, that is to say, with a
shank 1 and a cross head 2 formed at each end of the shank. These non-magnetic
lamina may be made of zinc, brass, copper or other like metal and they are covered
on both sides with a thin adherent film of tin, or other easily fusible non-magnetic
metal; this is done by the ordinary process of tinning, and it is of no consequence
whether in this process the edges of the lamina are also tinned or not, except as
will be hereinafter set forth.
For each lamina of non-magnetic metal, I provide two lamina of soft iron,
which are also tiuned on both sides, and are therefore, preferably cut from the
ordinary tinned sheet-iron. These magnetic lamina are shaped as shown in
Figure 2, that is to say, with a shank 3 and a cross-head 4 at one end of the shank
only. The shank 3 and the cross-head 4 have the same width as the like elements
in the non-magnetic lamina and the length of the cross-head 4 is equal to that of the
cross-head 2, while the shank of the magnetic lamina may be made either of the
same length as the shank 1 as indicated in dotted lines in Figure 2, or by preference
it may be made only half the length of the shank of the non-magnetic lamina, as
indicated in solid lines in Figure 2.
In
Having provided a great number of these magnetic and non-magnetic lamina,
they may be put together to form a corc-element, in a variety of ways.
Figure 3, one such core element is shown, and it will be seen that it is made
of non-magnetic lamine with two magnetic lamine applied with the ends of
their short shanks toward each other, on the same side of the non-magnetic lamina.
As has been stated above, the lamina are tinned on each side, and when applied
to each other in the manner indicated in Figure 3, they are heated under pressure
until the tianed surfaces in contact become fused or sweated together.
By reference to Figures 1 and 2 it will be seen that in the centre of each cross-
head there is a perforation 5, and it will be clear that when a core-element, like
that shown in Figure 3 is completed, the perforations in the magnetic lamina will
coincide with the perforations in the non-magnetic lamina; if desired, these
perforations may be made after the sweating together of the magnetic and non-
magnetic lamina, but under all circumstances, they must be in each core element in
precisely the same position in the cross-heads.
The end edges 6 of the shanks of the magnetic laminæ need not be carefully
made to be in close magnetic contact and in fact I have found that these edges may,
with advantage, be out of contact, or separated from each other by a thin film of
tin, which, in the process of making the core-element will eventually be forced
between them. The long edges 7 of the cross-heads of the magnetic lamina how-
ever, must be free of tin or any other non-magnetic substance, for reasons which will
hereinafter more fully appear.
The core elements shown in Figure 3 are assembled to form a converter core in
the manner indicated in Figure 4,-that is to say, they are piled upon each other,
or strung upon two bolts 8, 8, by means of which, and by suitable nuts 9, 9, they
are bolted together. As will be seen by reference to Figure 4, the core elements
are so piled upon each other that the magnetic lamina of one is separated from the
magnetic laminæ of the next succeeding one by a non-magnetic lamina.
When the core elements are thus assembled, the core has the shape shown in
Figure 9, the assembled cross-heads constituting the flanges 10 of the core 11, upon
which the layers of insulated wire of the transformer are coiled.
In Figure 10 the coils of insulated wire are shown applied to the core, the
coarse wire 12 in this instance being shown next to the core and the fine wire 13
covering the coarse wire; but,, as is well understood, this arrangement may be
reversed.
In Figure 5 another form of core-unit is shown,-in this case it will be seen that

page_text: each unit consists (as in the construction so far described) of a lamina of non-
magnetic metal and two lamina of magnetic metal, but in this case the magnetic
lamine are sweated to opposite sides on the same end of the non-magnetic laminie.
When such core elements are assembled, as indicated in Figure 6, the group formed
is substantially like that shown in Figure 4, except that the terminal plates show a
break of continuity, which is remedied by the addition at each end of the magnetic
lamine as indicated in dotted lines at 31, 4'.
I have so far described the use of magnetic lamina, the shanks of which are
only half as long as the shanks of the non-magnetic laminæ, but, as stated above,
the shanks in both lamina may have the same length; in which case, the core unit
will appear as in Figure 7 and the assemblage of the same will appear as in
Figure 8. At each end plate, therefore, the cross-head will have a depression
which may be filled out by a supplemental cross-head 4¹ of non-magnetic material 2',
as indicated in dotted lines. In this constriction, the magnetic cross-heads in
the alternate core-units will be missing, and I have found that the efficiency
of conversion is thereby not only not impaired, but is actually improved. If so
desired, the gaps between the successive cross-heads may be filled out by non-
magnetic material.
It will be noticed that in this construction, there are between two successive
non-magnetic lamina, two magnetic lamina, but these two are not in magnetic
contact, since the surfaces of the iron are tinned. We have therefore, in this
instance, as in the other forms described, alternate layers of iron and non-
magnetic material, the successive laminae of non-magnetic material, however, being
composed alternately of tinned zinc, brass or copper, and of two thin layers of tin
respectively.
When the converter core is finished in the manner hereinbefore described, and
the coils of insulated wires have been applied, the magnetic shield bridging the
polar terminals of the core is applied. By preference this magnetic shield is
made of two heavy bands of soft iron constructed as shown in Figure 10,-that
is to say, each of a plate of iron extending from the middle of one flange of the
core and in contact therewith, as indicated at 14 then bent around the edge
of said flange and extending down to the other flange of the core, as indicated
at 15, where it is again bent at right angles, extending to the middle of this second
flange.
This band is, besides, provided with an upright flange 16, at each end, and the
two bands, when assembled upon the core, in the manner shown in Figure 10, are
joined by their flanges 16 and form a magnetic shield, or more correctly speaking, a
magnetic circuit, for the line of force. This shield, therefore, being composed of
two separable parts, may be slipped onto the converter when otherwise finished, and
may be removed for inspection and repair.
While I use by preference the construction of magnetic shield thus described
with reference to Figure 10, I may also use the hood or cup-shaped construction
indicated in Figure 11, which in effect is nothing but a housing of iron, inclosing
the converter on all sides. It is made like the construction shown in Figure 10,
in two parts, each part being provided with lugs 17, 17, by means of which the
said parts are coupled together. I have found, however, that a complete magnetic
circuit or path for the magnetic lines of force between the pole terminals
must not necessarily inclose the converter upon all sides, and the construction shown
in Figure 10 being the cheaper and having the same efficiency as a hood or cup,
I use by preference a magnetic shield or circuit composed of two angular bands of
soft iron.
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. A core for an electrical converter or inductorium, laminated in planes
parallel to i s axit, and, at right angles thereto, substantially as described,

page_text: 2. A core for an electrical converter or inductorium, composed of laminæ of
magnetic material separated by laminæ of non-magnetic metal, substantially as
described.
3. A core for an electrical converter or inductorium, composed of laminæ of
tinned iron, with lamine of non-magnetic metal interposed between them, sub-
stantially as set forth.
4. A core element for an electrical converter or inductorium, consisting of a sheet
of non-magnetic metal having one or more lamina of iron fused to its surface or
surfaces, substantially as described.
5. A core element for an electrical converter or inductorium, consisting of
a thin sheet of non-magnetic metal formed with a shank and a cross-head at
each end, in combination with two lamina of iron each formed with a shank
having half the length of the shank of the sheet of non-magnetic metal, and a
single cross-head, and fused to the sheet of non-magnetic metal, substantially as
set forth.
6. A core element for an electrical converter or inductorium consisting of an
I-shaped lamina of non-magnetic metal in conbination with two T-shaped lamina of
magnetic metal fused to and covering the non-magnetic lamina, substantially as
described.
7. In an electrical converter, or inductorium, the combination of a laminated
core having free polar terminals, with a magnetic shield composed of two flanged
angle-irons closely fitting the poles of the core and each other, substantially as set
forth.
Date 1...
1001
REGINALD W. BARKER.