Improvements in Electric Condensers.
Year: 1895

page_text: Date of Application, 9th Mar., 1895
Complete Specification Left, 6th Dec., 1895-Accepted, 11th Jan., 1896
Improvements in Electric Condensers.
SEBASTIAN ZIANI DE FERRANTI, 27, Charterhouse Square in the County of
London, Electrician and Engineer, do hereby declare the nature of this invention
to be as follows:-
This invention has for its object improved means of constructing electric
condensers in such a manner that they may better stand the service for which
they are intended, than those otherwise built.
According to my invention I construct electric condensers in which I prefer
to use ebonite or its equivalent as the di-electric. Hitherto tin-foil or some
such substance has been used as the conductor on the surface, or between the
di-electric plates. The air occluded between the surfaces has had a most pre-
judicial effect and a bombardment of the surfaces of the di-electric has taken
place owing to the space which, under the most careful treatment, must always
remain between the surfaces.
Upon my improved method I coat the di-electric by means of a chemical
deposition process, or by means of an electro-chemical deposition process, or a
combination of both of them, with metal.
According to one method I take a sheet of ebonite and treat this in the same
way as glass is treated for silvering by any of the well-known processes for
making looking glasses, by this means I deposit a thin layer of silver over the
surface of the ebonite and in atomic contact with the surface. This acts as an
electrical conductor and by this means I may then thicken the deposition by
electro-deposition.
In some cases I may electro-deposit metal upon the surface of the di-electric
by means of first laying on some conducting base other than silver, provided
always that the deposited metal is in intimate contact with the di-electric.
In other cases I may trust to chemical deposition only and cover the necessary
surface of the di-electric by this means alone to a sufficient thickness to take
1e desired current.
Hitherto it has been customary in making a condenser first to take a sheet
of di-electric upon this to lay a sheet of tin foil then a sheet of di-electric and so
on, but according to my invention 1 coat both sides of the di-electric with a metal
deposit in intimate contact with both of its surfaces.
In order to make up a condenser I then take a sufficient number of these
di-electric plates, with .ctal on cach side of them, and place them side by side
either in contact, or in close proximity to each other just as photographic negatives
in a plate box, and fill up the remaining air spaces with oil, wax, or some other
suitable insulating or preservative compound. The space between the plates will
not act detrimentally in this case as both plates upon adjacent surfaces of di-electrics
are charged to the same electrical potential, the difference of potential only occur-
ring from side to side of the di-electric and without air space intervention. These
plates I prefer to connect together by means of very fine wires or strips of metal,
which come out separately to the rods or wires forming the poles of the condenser,
and which act as fuses and cut out a defective plate in case of anything happening
to one of the plates of the set, and so avoiding the general breakdown of the whole
condenser due to a single small fault in the first instance.

page_text: According to another method I may construct condensers by means of rolling
together two sheets of tin foil or equivalent material and the necessary di-electric,
In
using a considerable pressure so as to get intimate contact and to exclude air.
this case prefer to use for the di-electric thin sheets of vulcanised rubber.
In some cases cbonite may be used or in others paper and wax may be employed..
I prefer to carry out this process in a vacuumn in a tank formed for the purpose,
preferably with a glass lid so as to see what going on, fitted with the necessary
turning and rolling gear, connection being made through the outside with suitable
glands and stuffing boxes which will enable the vacuum to be maintained.
In some cases where condensers are made with a metallic coating on each side
of the di-electric I may put fireproof material in between the plates of like
potential, so that any accident happening to one plate may not be communicated to
the rest of the condenser.
Dated thin Wighth day of Mab 1905
SEBASTIAN ZIANI DE FERRANTI, 27, Charterhouse Square in the County of
London, Electrician and 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:—
This invention has for its object improved means of constructing electric
condensers in such a manner that they may better stand the service for which they
are intended, than those otherwise built.
According to my invention I construct electric condensers in which I prefer to
use ebonite or its equivalent as the di-electric. Hitherto tin-foil or some such
substance has been used as the conductor on the surface, between the di-electric
plates. The air occluded between the surfaces has had a most prejudicial effect
and a bombardment of the surfaces of the di-electric has taken place owing to the
space which, under the most careful treatment, must always remain between the
surfaces.
Upon my improved method I coat the di-electric by means of a chemical
deposition process, or by means of an electro-chemical deposition process or a
combination of both of them with metal.
According to one method I take a sheet of ebonite and treat this in the same
way as glass is treated for silvering by any of the well-known processes for making
looking glasses, by this means I deposit a thin layer of silver over the surface of
the cbonite and in atomic contact with the surface. This acts as an electrical
conductor and by this means I may then thicken the deposition by electro-
deposition.
In some cases I may electro-deposit metal upon the surface of the di-electric
by means of first laying on some conducting base other than silver, provided
always that the deposited metal is in intimate contact with the di-electric.
In other cases I may trust to chemical deposition only and cover the necessary
surface of the di-electric by this means alone to a sufficient thickness to take the
desired current.
Hitherto it has been customary in making a condenser first to take a sheet
of di-electric upon this to lay a sheet of tin-foil then a sheet of di-electric and
so on, but according to my invention I coat both sides of the di-electric with a
metal deposit in intimate contact with both of its surfaces.
In order to make up a condenser I then take a sufficient number of these
di-electric plates, with metal on each side of them, and place them side by side

page_text: either in contact or in close proximity to each other just as photographic
negatives in a plate box, and fill up the remaining air spaces with oil, wax, or
some other suitable insulating or preservative compound. The space between the
plates will not act detrimentally in this case as both plates upon adjacent surfaces
of di-electrics are charged to the same electrical potential, the difference of
potential only occurring from side to side of the di-electric. These plates I prefer
to connect together by means of very fine wires or strips of metal, which come out
separately to the rods or wires forming the poles of the condenser and which act as
fuses and cut out a defective plate in case of anything happening to one of the
plates of the set, and so avoiding the general breakdown of the whole condenser
due to a single small fault in the first instance.
According to another method I may construct condensers by means of rolling
together two sheets of tin foil or equivalent material and the necessary di-electric,
using a considerable pressure so as to get intimate contact and to exclude air. In
this case I prefer to use for the di-electric thin sheets of vulcanised rubber. These
sheets are vulcanised with the tin foil on them or the tin foil may be put on to
partially vulcanised sheets which are afterwards finally cured to the desired extent
and in some cases forming ebonite. I prefer to carry out this process in a vacuum
in a tank formed for the purpose preferably with a glass lid so as to see what is
going on, fitted with the necessary turning and rolling gear, connection being made
through the outside with suitable glands and stuffing boxes which will enable the
vacuum to be maintained.
In some cases where condensers are made with a metallic coating on each side of
the di-electric I may put fireproof material in between the plates of like potential,
so that any accident happening to one plate may not be communicated to the rest
of the condenser.
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.) Electric condensers in which the electrodes are in intimate or atomic contact
with each side of the di-electric.
(2.) Condensers in which each di-electric plate is coated with its own metallic
surface on both its sides.
(3.) Forming condensers of di-electric plates suitably connected, each plate
having its own metallic surface upon both its sides.
(4.) Metallising the surfaces of the di-electric by chemical or electrical
deposition or a combination of both.
(5.) Forming condensers by means of rolling the necessary parts together under
pressure.
(6.) Building up condensers under a vacuum substantially as described.
(7.) Connecting the metal surfaces of condensers in parallel through fuses so as
to cut out a faulty section.
(8.) Dividing the plates in condensers by fireproof partitions.
(9.) My improvements in the manufacture of electric condensers substantially as
described.
(10.) My improved electrical condensers substantially as described.
Dated this 6th day of December 1895.