Improvements in Devices for Protecting Electric Circuits and Apparatus from Injury by Excessive Electrical Potential due to Lightning or other cause.
Year: 1895

page_text: Date of Application, 20th Dec., 1895
Complete Specification Left, 21st Sept., 1856-Accepted, 7th Nov., 1896
PROVISIONAL SPECIFICATION.
Improvements in Devices for Protecting Electric Circuits and
Apparatus from Injury by Excessive Electrical Potential due
to Lightning or other cause.
We, VALERE ALFRED FYNN, Electrician to Easton, Anderson, & Goolden,
Limited, of Erith Iron Works, Erith, in the County of Kent, and EASTON,
ANDERSON & GOOLDEN, LIMITED, of the same place, do hereby declare the
nature of this invention to be as follows:-
The object of this invention is to provide efficient protective means whereby, on
the undue rise of potential, in an electric circuit, due to lightning, or other cause,
the discharge to earth is effected without danger to the circuit, or apparatus, aud
without the setting up of an injurious arc at the protective device, or arrester.
According to this invention there is arranged in a connection between the line
and earth, large surfaces of metal (preferably brass) supported at such a distance
from each other as to give a sufficient air space between them to prevent any
discharge of current at normal potential, but to allow discharge for abnormal
potential before that potential reaches such a degree as to be liable to cause
damage to the circuit, or apparatus. The said surfaces of metal are constituted by
discs, or plates, supported at distances from each other and in number in
accordance with the desired sensitiveness of the apparatus. The device is prefer-
ably constructed as follows:-In a suitable casing is supported a conductive
holder electrically connected with the line, which conductive holder carries a glass
rod upon which are held brass discs, or plates, with glass, or other, insulating discs,
or filling pieces, between them of such a thickness as to maintain the requisite air
space between the discs, or plates. The first disc is electrically connected through
the conductive holder or otherwise to the line and the last disc, or plate, of the
series is electrically connected to earth. The casing may have a glass, or other
easily fractured, bottom to it. On the occurrence of undue increase in potential a
discharge takes place across the discs, or plates, to earth, thus reducing the
potential to its normal value. In case the current in the line should follow this
discharge and an are be set up, the heat generated fractures the glass supporting
rods, and the discs, or plates, and distance pieces, consequently, fall, and the glass
or equivalent, bottom of the casing if used is fractured by their fall, and injurious
arcing of the current at the arrester is thus prevented.
Dated this 20th day of December 1895.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents for the Applicants.
-
COMPLETE SPECIFICATION.
Improvements in Devices for Protecting Electrio Oirouits and
Apparatus from Injury by Excessive Electrical Potential due
to Lightning or other cause.
We, VALERE ALFRED FYNN Electrician to Easton Anderson & Goolden
Limited of Erith Iron Works, Erith in the County of Kent and EASTON
ANDERSON AND GOOLDEN LIMITED of the same place do hereby declare the
[Price 8d.]
·

page_text: 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 object of this invention is to. provide efficient protective means, whereby, on
the undue rise of potential, in an electric circuit, due to lightning, or other cause,
discharge to earth is effected without danger to the circuit, or apparatus, and
without the setting up of an injurious are at the, protective device, or arrester.
According to this invention there is arranged in a connection between the line
and earth, large surfaces of metal (preferably-brass) supported satisucbvardistance
from each other as to give a sufficient air space between them-to-prevent any
discharge at normal potential, but to allow discharge for abnormál, potential before
that potential reaches such a degree as to be liable to cause damage to the circuit
or apparatus. The said surfaces of metal are constituted by discs, or plates,
supported at distances from each other and in number in accordance with the
desired sensitiveness of the apparatus. The device is preferably constructed as
follows: In a suitable casing support or holder is a glass rod upon which are held
brass discs or plates, with glass, or other insulating and non-combustible discs or
distance pieces between them, of such a thickness as to maintain the requisite air
_space between the discs, or plates. The first disc is electrically connected in any
suitable manner but most conveniently through the conductive casing, support, or
holder, to the line, and the last disc, or plate, of the series is electrically connected
to earth. The casing, support or holder may have a glass, or other insulating
-bottom to it. On the occurrence of undue increase in potential a discharge takes
place across the discs or plates to earth, thus reducing the potential to its normal
value. In case the current in the line should follow this discharge and an arc be
set up, the sudden beat generated fractures the glass supporting rod, and the discs
or plates and distance pieces consequently fall out of the casing together with the
bottom of the casing, if such bottom be used, and any injurious arcing of
-the current at the arrester is thus prevented.
In order that the invention may be clearly understood we shall now proceed
more particularly to describe an apparatus constructed in accordance there with
and for that purpose shall refer to the accompanying drawings, the same letters of
reference indicating corresponding parts in all the figures.
Figure is a vertical section and Figure 2 a plan of a protective device
constructed according to this invention and Figure 3 shews a means for attaching
the arrester to a pole carrying an overhead line.
The apparatus can be used either indoors, or out of doors for protecting
overhead lines against abnormal high potentials caused either by direct lightning
discharges, or produced by lightning discharges occurring in the neighbourhood of
the line. It can also be used for protecting underground net work against damage
by undue rise of potential caused by capacity effect, or by the combination of
capacity and self induction, or otherwise.
A is a case which may be of galvanized cast iron or other suitable conductive
material as in the arrangement shewn it is used as the means for electrical-connec-
tion of the device to the line. The said case A is provided on the exterior with
lugs or internally screwed projections a to which can be screwed a metal band, or
strap, b, by which the arrester can be suspended from an insulator 64 as shewn in
Figure 3. On the exterior of the case is formed a socket B in which can be
secured, by screws, or otherwise, one end of a conducting wire b³ the other end of
which is connected to the line 63 to be protected.
Inserted from the interior and passing through a hole in a boss formed on the
crown, or top, of the case A is the stem of an internally screwed metal sucket d
the end of the stem, projecting above the boss and being provided with a
transverse hole in which is inserted aspin e by which to secure.the-stem and socket
in position and the projecting end of the stem c is covered by a cap o C is a
glass rod having at the lower.end a head, or shoulder, C2, supporting a number of
metal discs D (preferably of brass) threaded on the said rod, the said discs being
retained out of contact with each other and at the requisite distance apart, by

page_text: interposed washers of glass or other insulating and non-combustible material
as shewn at threaded on the glass rod, or by small balls, beads, or discs, of glass,
or other suitable non-conducting and non-combustible material arranged at suitable
distances apart between the discs as shewn at . On the upper end of the glass
rod C, is fixed a metal ferrule E provided externally with a screw thread to
screw into a corresponding internal thread in the socket d by which the rod C, and
the discs D, are supported. Care should be taken to use glass as free as possible.
from metals, or salts of metals which are good conductors of electricity such as
lead, iron, copper or the like. Glass should be employed in the manufacture of
which potassium, calcium, sodium or the like has been used. The first or upper-
most of the discs D, is in contact with the metal socket d and is consequently
electrically connected to the case A, and thence by the wire 6' to the conductor to
be protected. The last or lowermost of the discs D, is connected to earth by a
rod or wire F attached to the said lower disc D, and passing through the head C
on the rod C, to which rod or wire F is connected a conductor leading to earth..
The peripheries of the discs should be rounded as shewn and the surfaces of the
discs be highly polished, as sharp edges or points of any kind would cause the
sparking to take place always at the same spot and this is to be avoided.
The lower open end of the case A is closed by a glass plate G, which may be
supported on a shoulder g formed on the head C³, of the rod C, an india rubber
ring, or washer being interposed between the plate G, and the case A, to exclude
dust and insects from the interior of the case. For indoor use the case need not be
so carefully closed. In case of a discharge due to rise of potential in the circuit.
from any cause, the heat generated by the sparks, caused by the said excess.
of potential, will be readily dispersed through the metal discs D. In case the
apparatus should fail to act normally, and consequently the discharge be such as to
cause a lasting arc to be set up in the apparatus, the heat generated thereby in the
discs D will cause the glass rod C to break, and then the discs D, and earth.
connection will fall and so break the circuit and destroy the arc.
Figures 4 and 5 are diagrams shewing respectively, the connection of the devices.
to the conductors of single, and concentric cables. In these figures the devices are
marked A, and the connections to earth are marked E. In Figure 4 are the
single cables and in Figure 5 and are respectively the inner and outer
conductors of the concentric cable to which the connections to earth may be made
as shewn.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we declare that what we
claim is:-
1. In apparatus for protecting electric circuits and apparatus from injury by
abnormal rise of potential a device comprising in combination with a conductor to
earth metal pieces arranged at such distances apart as to prevent discharge
of current at normal potential but allow discharge at abnormal potential, before it
reaches such a degree as to be liable to damage the circuit or apparatus, the said
metal pieces being carried on a rod or holder which if the discharge produces
a lasting arc will break or be rendered useless for supporting the metal pieces and
so destroy the circuit substantially as hereinbefore described.
2. The combination and arrangement of parts constituting the apparatus
for protecting electric circuits and apparatus from damage by abnormal rise
of potential substantially as hereinbefore described and illustrated in Figures 1,
2 and 3 of the accompanying drawings.
Dated this 21st day of Sentember 1896
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.