Improvements in High Tension Transformers and Induction Coils for Roentgen Ray Work and for other Purposes.
Year: 1898

page_text: Date of Application, 9th Apr., 1898
Complete Specification Left, 20th Dec., 1898-Accepted, 25th Feb.,
1899
PROVIDIONAL DITUIFICATION.
Improvements in High Tension Transformers and Induction Coils for
Roentgen Ray Work and for other Purposes.
ALBERT LEWIS DAVIS, "Ranmore," Strawberry Hill Road, Twickenham, do
hereby declare the nature of this invention to be as follows;-
My invention relates to improved methods of construction of transformers &
induction coils for Roentgen ray work & for other purposes where high insulation
& high potential are required. The primary system or thick wire windings of
the coil or transformer may be enclosed in an insulating tube in the usual manner,
the secondary or high tension windings are preferably subdivided into a number
of flat sections the width & diameter & number of such sections being regulated by
the size and output of the transformer or coil, each pair of high tension sections are
separately enclosed in a specially shaped insulating cell made of vulcanite or other
suitable insulating material, these cells are preferably made in two halves, and may
conveniently be made as follows, circular pieces of vulcanite or other suitable
insulating material are first cut from sheet of suitable thickness & diameter, an
annular depression in the centre of the disc is then made by means of a hot steel
die in a manner such that the insulating disc assumes the shape of a flanged disc
having a hole in the centre of the flanged portion just large enough to allow the
Hanged or turned up rim in the centre of the insulating disc to pass over the outside
of the insulating tube containing the primary wire & core, the flanged or turned
up portion of the insulating disc is of a width equal to that occupied by one pair
of the fine wire coils forming the high tension circuit of the coil or transformer, a
similar disc is now made of smaller diameter & having the annular flanged or
turned up portion of the same width as before but of a diameter such that the
flanged portion of the one disc just slides over that of the other, in a manner such
that when the two discs are placed in position they form a narrow insulating reel
leaving a space between the two cheeks, one cheek being of larger diameter than
the other. When a sufficient number of flanged discs as above described have been
made the high tension portion of the coil or transformer may be conveniently built
up as follows.
One of the flanged insulating discs having the cheek of larger diameter is placed
in position on the outside of the primary tube, one of the fine wire coils is then
placed over the flanged portion of the disc & against the cheek of the disc, a flat
insulating washer is now placed next to the fine wire coil, then a second coil is
placed in position, & is followed by the second insulating flanged disc having the
cheek of smaller diameter, this completes the first pair of coils, the latter being
wound in opposite directions & having the inner ends of their windings soldered
together in the usual manner; all the sections are built up in the above manner
& in the same order, each pair of coils being encased in its separate insulating cell
constructed as above described, neighbouring coils being connected together as
usual in series. From the above method of construction it will be seen that no

page_text: space is wasted, the high tension wire can be wound in closer proximity to the
primary tube, without fear of leakage between neighbouring sections, than is
possible with other forms of construction, & the tendency to sparking. between
adjacent sections is prevented owing to the fact that any such leakage between two
adjacent sections is obliged to follow a zigzag path equal to four times the width of
one pair of flanged insulating discs; the result being a very much higher efficiency
from a given weight of wire than has been possible hitherto.
Datod this Sawanth day of 1000
Improvements in High Tension Transformers and Induction Coils for
Roentgen Ray Work and for other Purposes.
ALBERT LEWIS DAVIS, "Ranmore," Strawberry Hill Road, Twickenham,
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 relates to improved methods of construction of transformers and
induction coils for Röntgen ray work and for other purposes where high insulation
and high potential are required. The primary system or thick wire windings of
the coil or transformer may be inclosed in an insulating tube in the usual manner;
the secondary or high tension windings are preferably subdivided into a number
of flat sections; the width and diameter and number of such sections being regulated
by the size and output of the transformer or coil, each pair of high tension sections
are separately enclosed in a specially shaped insulating cell made of vulcanite or
other suitable insulating material. These cells are preferably made in two halves,
and may conveniently be made as follows;-
Circular pieces of vulcanite or other suitable insulating material are first cut
from sheets of suitable thickness and diameter, an annular depression in the
centre of the disc is then made by means of a hot steel die, shaped in a manner
such that the insulating disc assumes the shape of a flanged disc, having a hole
in the centre of the flanged portion just large enough to allow the flanged or
turned up rim in the centre of the insulating disc to pass over the outside of the
insulating tube containing the primary wire and core, the flanged or turned up
portion of the insulating disc is of a width equal to that occupied by one pair of
the fine wire coils forming a portion of the high tension circuit of the coil or trans-
former. A similar disc is now made of smaller diameter and having the annular
flange or turned up portion of the same width as before but of a diameter such that
the Hanged portion of the one disc just slides over that of the other in a manner
such that when the two discs are placed in position they form a narrow insulating
reel having a space between the two cheeks, one cheek being of larger diameter
than the other; when a sufficient number of flanged discs as above described have
been made, the high tension portion of the coil or transformer may be conveniently
built up as follows:-
One of the flanged insulating discs having the cheek of larger diameter is placed
in position on the outside of the primary tube, one of the fine wire coils is then
placed over the flanged portion of the disc and against the cheek, a flat insulating
washer is now placed next to the fine wire coil, then a second coil is placed in
position and is followed by the second insulating flanged disc having the cheek of

page_text: smaller diameter; this completes the first pair of coils, the latter being wound
in opposite directions and having the inner ends of their windings soldered together
in the usual manner. All the sections are built up in the above manner and in
the same order, each pair of coils being enclosed in its separate insulating cell con-
structed as above described; neighbouring coils being connected together as usual
in series.
From the above method of construction it will be seen that no space is wasted,
and the high tension wire can be wound in closer proximity to the primary tube
without fear of leakage between neighbouring sections than is possible with other
forms of construction, and the tendency to sparking between adjacent sections is
prevented owing to the fact that any such leakage between two adjacent sections
is obliged to follow a zig-zag path, equal to four times the width of one pair of
flanged insulating discs; the result being a very much higher efficiency from a
given weight of wire than has been possible hitherto.
On the accompanying drawings similar parts are indicated by similar reference
letters, Fig. I, A, A, A", shows three stages of construction of the flanged discs.
Fig. II, A, B, C, shows the three component parts forming one complete insulat-
ing cell, the dotted portions being removed in order to more clearly show the shape
of the parts.
Fig. III, is a perspective view in part section of a complete insulating cell wi
with
the two fine wire coils and insulating washer in position.
Fig. IV, shows a sectional elevation of the insulating cells made in one piece in
lieu of two halves.
Fig. V, shows a complete coil or transformer in section.
All the above figures are drawn to the scale indicated on the drawing.
On reference to Fig. V, I, is the iron wire core of the primary system over which
may be wound the primary or thick wire winding, portions of which are indicated
in section at P, P. This may be enclosed in an insulating tube in the usual
manner, made of vulcanite or other suitable insulating material and of a thickness
depending on the potential difference at the terminals of the secondary or high
tension windings.
The secondary or high tension windings are preferably subdivided into a number
of flat sections, the width and diameter being regulated by the size and output of
the transformer or coil, each pair of high tension sections are separately enclosed
in a specially shaped insulating cell, Fig. III, and Fig. 5, S, made of vulcanite
or other suitable insulating material. These cells are preferably made in two halves,
Figs. I, III and V, A, C, and if vulcanite is used may conveniently.be made as
follows:-
Circular pieces of sheet vulcanite of suitable thickness and diameter are first cut,
an annular depression, Fig. I, A" is then made by means of a hot steel die, a second
hot die is then used, shaped in a manner such that the insulating
disc assumes the shape of the flanged disc. A Fig. I, the portion J,
Fig. I is then cut away and the finished disc will then assume the
appearance shown in Fig. I, A, having a hole in the centre of the
flanged portion just large enough to allow the flanged or turned up rim U in the
centre of the insulating disc to pass over the outside of the insulating tube, T,
Fig. V. A similar disc is now made of smaller diameter and having the annular,
flanged, or turned up portion, U, Fig. II of the same width as before, but of a
diameter such that the flanged portion of the one disc just slides over that of the
other; preferably the flanged portion U of the disc A, Fig. II should slide over and
outside the flanged portion U of the disc C in a manner such that when the two
discs are placed in position they form a narrow insulating reel, Fig. III, having
a space between the two cheeks, one cheek A, being of larger diameter than the
other cheek C. The insulating discs.are preferably made for ease of manufacture,
as described, in two halves, they may, however, be formed if required, in one piece
as shown in section at Fig. IV, in this case the shape of the moulding die should
be modified to suit and produce the special shape indicated, the central insulating

page_text: washer B, should be placed in position before moulding the smaller cheek C,
Fig. IV.
When a sufficient number of flanged discs as above described have been made,
the high tension portion of the coil or transformer may be conveniently built up
as follows:-
One of the flanged insulating discs A, having the, cheek of larger diameter is
placed in position on the outside of the primary tube T, Fig. V one of the fine
wire coils S is then placed over the flanged portion of the disc against the cheek,
the flat insulating washer B, is now placed next to the fine wire coil, then a second
coil is placed in position and is followed by the second insulating flanged disc C,
having the cheek of smaller diameter; this completes the first pair of coils, the
latter being wound in opposite directions and having the inner ends of their wind-
ings soldered together in the usual manner at F, Fig. III. If the type of insulat-
ing cell made in one piece without joint, shown in Fig. IV is used, the high tension
wire must be wound in the cell itself, the latter being mounted on a suitable former
during the process, a split metal washer or distance piece taking the place of the
second coil until the first coil is wound, after which the metal distance piece may be
removed and the second coil may be wound on the other side of the loose insulating
washer B. Care must be taken to wind the coils in opposite directions, as stated
above. If required this method of winding may also be followed when using the
insulating cells made in two halves, Fig. II; the component parts being put
together first and mounted on a former as above described. In both cases it is
advisable to keep the reel from which the wire is being wound immersed in hot
paraffin wax. All the sections are built up in the above manner and
each pair of coils being encased in its separate insulating cell con-
structed as above described and in the same order, neighbouring coils of adjacent
cells being connected together as usual in series by their outer ends L L' (Fig. III).
In comparatively small induction coils or transformers, or where the potential
difference generated by each pair of fine wire coils is insufficient to cause a spark
in air of a length less than the width of the turned up portion U of the insulating
disc A, then the portion C may be omitted. From the above method of construction
it will be seen that no space is wasted, the high tension wire S, Fig. V, can be
wound in closer proximity to the primary tube T without fear of leakage between
neighbouring sections than is possible with other forms of construction and the
tendency to sparking between adjacent sections is prevented, owing to the fact that
any such leakage between two adjacent sections is obliged to follow a zig-zag path
equal to four times the width of one pair of flanged insulating discs; the result
being a very much higher efficiency from a given weight of wire than has been
possible hitherto. In view of the fact that a coil made according to this plan will
give sparks in air more than twice the entire length of the high tension system S
Fig. V, it is necessary to guard against leakage over the outside surface of the
insulating tube T into the primary system P, P and the core I; this leakage may
be prevented by screwing the ends of the tube T into supporting pieces K of
vulcanite or other suitable insulating material, and also by screwing on the tube T
a stout insulating disc D; in order to secure a good joint the supporting piece K
and the disc D should be screwed into position whilst immersed in hot paraffin
wax, additional insulating discs D₁ serve as a support for two vulcanite tubes H.
encasing the ends of the high tension system S, the spaces W may now be filled
with hot paraffin wax, and to give a finish to the instrument thin vulcanite covers E
may be placed round the wax; the completed transformer or coil may be mounted
on a suitable baseboard and provided with terminals, condenser, contact breaker and
the usual adjuncts of any convenient type.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is:-
I. In the high tension system of a transformer or induction coil, the use of a

page_text: flanged insulating disc or series of discs A, each disc having a turned up portion U,
and forming a cell capable of receiving one pair of coils forming a portion of the
high tension system of the transformer or induction coil; each pair of coils being
separated by a suitable flat insulating washer or washers, and used in conjunction
with one flanged insulating disc A, substantially as described.
II. In the high tension system of a transformer or induction coil, the use of an
insulating cell or series of cells, built up of two flanged insulating discs A and C
each disc having a turned up portion U, the turned up portion of the one disc being
capable of sliding over the turned up portion of the other disc in a manner such
that when the two parts are assembled, a narrow reel or cell is formed having two
cheeks, the cheek of the one flanged insulating disc A being preferably of larger
diameter than the cheek of the other flanged insulating disc C. Each pair of coils
forming a portion of the high tension system of the transformer or induction coil,
being separated by a suitable flat insulating washer or washers B, is enclosed
between and used in conjunction with one pair of flanged insulating discs A and C
substantially as described.
III. In the high tension system of a transformer or induction coil, the use of
one or more flanged insulating cells; each cell having two cheeks preferably of
unequal diameter Fig. 4 one such cell being used in conjunction with and forming
an insulating cell for each pair of coils forming a portion of the high tension
system of the induction coil or transformer; each pair of coils being separated by
a suitable flat insulating washer or washers B, substantially as described.
IV. In the high tension system of a transformer or induction coil the com-
bination and use of the several parts herein described and figured, and for the
purposes set forth.
Doted this 10th dor of Donamba 1000