Improvements in Electrical Discharge Apparatus.
Year: 1896

page_text: Date of Application, 10th Nov., 1896
Complete Specification Left, 30th July, 1897-Accepted, 25th Sept., 1897
[Communicated from abroad by ALEXANDER JAY WURTS and CHARLES B.
SKINNER, both of Pittsburgh, in the County of Allegheny and State of
Pennsylvania, United States of America.]
Improvements in Electrical Discharge Apparatus.
I, REGINALD BELFIELD, of 32, Victoria Street, in the City of Westminster.
Electrician, do hereby declare the nature of this invention to be as follows:-
The invention relates to Electrical Discharge Apparatus which comprises
separated electrodes between which the discharges or sparks pass.
The object of the invention is to provide an improved apparatus which will
facilitate the passage of disruptive discharges. By this invention with a given
electromotive force a longer spark can be obtained than that obtainable from
apparatus hitherto in use."
Apparatus constructed according to this invention may be employed with
advantage for exhibition or laboratory purposes where it is desired to obtain a
long spark, but a particular application of the principle of this invention is in the
construction of lightning arresters as will be hereinafter described. In lightning
arresters it is desirable as well known, to have as great a distance between the
discharging terminals as possible in order to prevent leakage or arcing of the
ordinary line currents, but this distance must not be so great as to prevent
the passage of a disruptive static discharge between said terminals.
According to the present invention the terminals are placed in contact with r
in close proximity to a body or plate of insulating material and one of said
terminals is electrically connected with a conducting body placed on the opposite
side of said insulating body. By this arrangement the sparking distance is
increased by the presence of the surface of the insulating body and of the
conducting body on the opposite side of said insulating body.
In one form of the improved apparatus a sheet of glass is provided having one
side thereof coated with metal foil. The discharging terminals are supported in
close proximity to the uncovered side of the glass sheet and one of them is con-
nected by a wire either through a condenser or not to the metal foil on the other
side of the sheet.
In applying the invention to lightning arresters the terminals are preferal:ly
designed so as to prevent the continuance of an arc if one should be formed and
one of said terminals is connected to the circuit to be protected, and the other
terminal connected to the earth. Preferably the plain surface of the glass shet
between the terminal is covered with a conducting film in order to facilitate the
passage of a static discharge.
In a modification the insulating body takes the form of a tube lined internally.

page_text: with metal and the terminals are constituted by metal caps at the ends of the
tube, one of which caps is connected with the metal lining.
Dated this 5th day of November 1896.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.
improvements in Electrical Discharge Apparatus.
I, REGINALD BELFIELD of 32 Victoria Street in the City of Westminster,
Electrician, 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:-
The invention relates to Electrical Discharge Apparatus which comprises
separated electrodes between which the discharges or sparks pass.
The object of the invention is to provide an improved apparatus which will
facilitate the passage or disruptive discharges. By this invention with a given
electromotive force a longer spark can be obtained than that obtainable from the
apparatus hitherto in use."
Apparatus constructed according to this invention may be employed with
advantage for exhibition or laboratory purposes where it is desired to obtain a
long spark, but a particular application of the principle of this invention is in
the construction of lightning arresters as will hereinafter describes.
In lightning arresters it is desirable as well, known to have as great a distance
between the discharging terminals as possible in order to prevent leakage or
arcing of the ordinary line currents, but this distance must not be so great as to
prevent the passage of the disruptive static discharge between said terminals.
According to the present invention the terminals are placed in contact with or
in close proximity to a body or plate, insulating material and one of said terminals
is electrically connected with a conducting body placed on the opposite side of
said insulator body. By this arrangement the sparking distance is increased
owing to the presence of the surface of the insulating body and also by the
conducting body on the opposite side of said insulating body.
In the accompanying drawings:-
Figure 1 is a diagrammatic view of an apparatus embodying the principle of
the invention.
Figure 2 is a perspective view of a double pole lightning arrester constructed in
accordance with the invention.
Figures 3 and 4 are sections on lines a, al al Figure 2 respectively.
Figure 5 is a view of the under side of one of the end blocks shewn in Figure 2.
Figure 6 is a side elevation of a lightning arrester designed for low potential
circuits and.
Figure 7 is a longitudinal section of the same.
Referring to Figure 1, 1 and 2 are two electrodes separated a considerable
distance and placed in contact with one face of the plate 3 of insulating material.
This plate may be of any convenient material and thickness. Glass is found to
be a suitable material, although the invention is not limited in this regard, and
the thickness should be sufficient to preclude any puncturing or rupturing of the
same when employed in connection with high potentials. 4 is a plate of con-
ducting material which may be of any suitable metal and of any convenient
thickness. This plate is in close contact with the face of the insulating plate
opposite to that upon which the terminals 1 and 2 rest; and it may conveniently

page_text: be in the form of a: sheet. of metal foil. This plate or sheet is preferably of
sufficient length to bridge the space between the electrodes; but the invention is
not limited as regards the length of such plate or sheet. This metal plate or sheet
is electrically connected with one of the electrodes 2, as indicated in the drawings,
by means of a suitable conductor 5:. A condenser 6 may be interposed between
the electrode 2 and the plate 4, if desired, but this is not a necessary adjunct. The
connection may be made directly as indicated by the broken line 7. The
electrodes 1 and 2 are connected with a source of electrical energy 8, which, as
indicated in. the drawing, comprises a dynamo 9 and a transformer 10. This
source of energy may be a generator of statical electricity, if desired, as will be
readily understood. If the parts 1 and 2 are the electrodes of a static machine,
the length of the spark which may be secured from the machine for, laboratory
or exhibition purposes will be much longer than any that it has heretofore been
possible to secure.
In case the invention is utilized as a lightning arrester, it will be understood
that one of the electrodes will be connected to the line to be protected, and. the
other will be grounded.
In the lightning arrester shewn in Figures 2 to 5, 11 is the plate of insulating
material and 12 is the sheet of conducting material. Blocks 13 which may be
duplicates of each other are cemented to the upper surface of the plate 11 near the
respective ends of the same, cach block consisting of a body of insulating material,
preferably of wood; provided with a dovetailed groove or recess, in one end of
which is a metal terminal piece 15, and in the other end of which is a piece 16
preferably of hard wood provided with longitudinal shallow grooves burned into
its face, constituting what I have termed a discharge wedge.
One of the terminal plates or pieces 5 is connected to one side 17 of a high
potential circuit by a conductor 18, and the other to the other side 17' of such
high potential circuit by a conductor 19. A block 20 is cemented to the upper
surface of the plate midway between the blocks 13, and this block 20 is sub-
stantially the same in construction as the block 13 except that the metallic
terminal piece 15' is located at the middle of its dovetailed recess or groove, and
groove blocks 16 in au respects like the parts 16 above described, are located
at each side of the terminal piece 15. This terminal piece 151 is connected to
earth by means of a conductor 21. It is also electrically connected with the con-
ducting sheet or coating 12, preferably by means of a strip of metal foil 22
extending to the edge of the plate 11 over the same, along the top and under the
terminal piece 15. Either the whole of the upper surface of the plate 11, if con-
structed of glass, is ground, or, the spaces between the pieces 16 and 16' are ground
or roughened, and these last named spaces rubbed with plumbago or some similar
conducting material, as indicated at 23 in order to facilitate the passage of the
static discharge from either or both of the conductors 18, 19 to the terminal
piece 51 and thence to the ground. This construction of apparatus also tends to
facilitate the passage of the dynamo current, but to a less degree, and the
production and maintenance of an aro is prevented by the non-arcing terminal
blocks.
It will be understood from the foregoing description that these terminal
blocks 13 and 20 may be separated a distance very much greater than has been
possible with apparatus heretofore employed without materially impeding the
passage of static discharges.
It will also be understood that while a double pole lightning arrester is shewn,
the invention is equally applicable to a single pole arrester.
In Figures 6 and 7 is shewn a lightning arrester adapted for low potential
circuits, such, for instance, as those employed in telegraphy and telephony. In
the circuits employed for this class of work, the lightning arresters usually
employed have consisted of two electrodes brought into such close proximity to
each other that when a discharge occurred the electrodes were liable to be bridged
or beaded over. This difficulty is entirely avoided by the employment of the

page_text: apparatus here shewn, in which 24 is a glass tube, the outer surface of which is
preferably ground and rubbed with plumbago, as indicated in Figure 6. Inside
of this glass tube 24 is a metal tube 25 preferably slotted as indicated, in order
that it may be readily inserted into the tube 24 and closely fit the same. This
tube 25 may be in the form of metal foil, however, if desired, instead of the sheet
metal indicated in the drawing. The inner tube or coating 25 is electrically
connected at its outer end to one binding post 26 of the lightning arrester. The
electrode 26 is also connected with the outer surface of the tube 24 by means of
a slotted metal tube 27, the internal diameter of which is substantially the same
as the external diameter of the tube 24. The other binding post 28 of the arrester
is connected with the outer surface of the tube 24 by a metal tube 29, also prefer-
ably slotted in order to make a close fit between the said parts. The lightning
arrester thus constructed may be attached to any desired supporting base 30 by
means of brackets 31 or by any other suitable means.
It will be understood from the foregoing illustration and description that dis-
ruptive discharges will occur between the ends of the metal tubes 27 and 29
connected respectively with the binding posts 26 and 28 over the surface of the
glass tube 24, the passage of the discharge being facilitated by the particles of
plumbago adhering thereto, and that the distance between the inner ends of the
tubes 27 and 28 is sufficiently great to preclude any bridging of the space between
them by reason of the fusing together of the parts.
The forms of apparatus shewn are merely examples shewing practical embody-
ments of the principle of the invention, and may be variously modified and adapted
to particular purposes wherever it may be found useful without departing from
the spirit and scope of the invention.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed as communicated to
me by my foreign correspondents, I declare that what I claim is :-
Electrical Discharge Apparatus constructed substantially as described.
th day of July 1897.
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester and Birmingham,
Patent Agents for the Applicant.