IMPROVEMENTS IN THE CONSTRUCTION OF INSULATORS FOR ELECTRICAL PURPOSES
Year: 1883

page_text: LETTERS PATENT to Elphinstone Roe of Tolworth Lodge Surbiton in the
County of Surrey Electrical Engineer for an Invention of "IMPROVEMENTS
IN THE CONSTRUCTION OF INSULATORS FOR ELECTRICAL PURPOSES'
"
PROVISIONAL SPECIFICATION left by the said Elphinstone Roe at the Office
of the Commissioners of Patents on the 25th October 1883.
ELPHINSTONE ROE of Tolworth Lodge Surbiton in the County of Surrey
Electrical Engineer IMPROVEMENTS IN THE CONSTRUCTION OF INSULATORS FOR
ELECTRICAL PURPOSES
Hitherto Insulators have generally been made of Porcelain and other non
conducting substances which from their liability to breakage from Lightning frost
and other causes have necessitated a constant and serious expenditure for renewal-
My Invention consists in the construction of Insulators of metal (by preference
cast iron) coated with any suitable liquid vitreous material or substanco fused into
the surface of the metal.
The heat required necessarily varying according to the nature of the metal used.
A second coat of the vitreous material is then applied thus blending the same
thoroughly and forming a vitorous glaze which renders the insulators perfectly
non conducting

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Elphinstone Roe in the Patent Office on the 25th April 1884.
ELPHINSTONE ROE of Tolworth Lodge Surbiton in the County of Surrey
Electrical Engineer "IMPROVEMENTS IN THE CONSTRUCTION OF INSULATORS FOR
ELECTRICAL PURPOSES
"
Hitherto insulators have generally been made of porcelain and other non-
conducting substances which from their liability to breakage from lightning, frost
and other causes have necessitated a constant and serious expenditure for renewal.
My invention consists in the construction of insulators of metal by preference
cast iron coated with any vitreous material or substance suitable, so blended with
the surface of the metal as to render it a perfect insulator such combination giving
great strength and endurance and at the same time preventing the usual atmospheric
current leakage.
I will now proceed to describe the method I have found to answer in carrying
my invention into effect.
It has heretofore been proposed to construct electrical insulators of enamelled
metal but on account of the faulty methods employed in enamelling the same the
surface thereof has become cracked and blistered which is caused during the fusing
of the enamel by the expulsion of the gas confined in the pores of the metal
thereby rendering the metal useloss for insulating purposes.
In the manufacture of insulators according to my invention I first carefully
cleanse the same from dust and dirt by the usual process of brushing, I then wash-
them in warm water after which I expel nearly all the gas from the pores of the
iron and fill the said pores with rustless oxide by submitting the same to the
"Bower-Barff" process.
The insulators treated as above described are then allowed to cool after which
they are coated with any suitable hard enamel either by immersion in a bath of
such enamel or by brushing or dusting over the same with the said enamel in a
liquid form
The enamel I have found to answer consists of the following ingredients in about
the proportions stated :-

page_text: acquainted with for the purposes of my invention but I do not confine myself to
the mixture nor to the relative weights of the materials herein described nor do I
claim the method of preparing the surface of the metal nor the application of the
vitreous material separately considered But what I do claim is the manufacture of
electrical insulators of metal by first expelling the gases imprisoned within the
pores of the metal and preparing the surface of the metal by filling up such pores
and then applying one or more coatings of enamel thereto substantially as herein
described and for the purpose stated.
In witness whereof I the said Elphinstone Roe have hereunto set my hand and
seal this Twenty Fourth day of April in the year of our Lord One thousand eight
hundred and eighty four.