An Improvement in Electrical Controlling Switches.
Year: 1895

page_text: . Date of Application, 28th Jan., 1895
Complete Specification Left, 26th Oct., 1895-Accepted, 30th Nov., 1895
An Improvement in Electrical Controlling Switches.
We,
EDWARD HOPKINSON D.Sc. and ARTHUR PEMBERTON WOOD, both of
The Salford Iron Works, Manchester in the County of Lancaster, Electrical
Engineers, do hereby declare the nature of this invention to be as follows:-
Our invention relates to the construction and arrangement of electrical controlling
switches in such a manner as to prevent sparking or the existence of an electric arc
in the neighbourhood of any of the contacts. For this purpose, we fix on a base
of insulating material a number of contact pieces arranged at intervals in a circular
arc, each contact piece being made of iron or steel, and preferably coated with
copper to ensure better conduction. Under these contacts, but separated from
them by a sheet of vulcanite or other insulating material is fixed a plate of iron or
steel in the form of a circular sector.
An iron or steel central pin fixed to the base, passes through this sector plate,
and extends upwards some distance above the base, its upper end forming an axis
on which the switch turns. The body of the switch, which turns upon the axis,
having the contact arm projecting one way from it towards the contacts is of iron
or steel; the arm projecting the other way consists of bent plates of brass or other
suitable elastic material the ends of which bear upon a conducting segment fixed on
the base. To the body of the switch is attached a handle of non-conducting
material. The end of the iron or steel arm of the switch is formed as a box
containing a block of coppered carbon pressed downwards by a spring which can
be adjusted by a setting screw. The central pin has coiled round it a number of
convolutions of insulated wire which may form part of the main circuit or may be
in a shunt; when this coil is traversed by the current, the central pin, switch arm
and sector plate constitute an electromagnet, producing a powerful magnetic field
at and near any one of the contact pieces which for the time lies between the carbon
above it and the sector plate below it; this effectually prevents the existence of
an arc near the contact, as when formed it is at once blown out by the magnetic
action.
1
Tanna 1905
ABEL & IMRAY,
Agents for Applicants.
We, EDWARD HOPKINSON D.Sc. and ARTHUR PEMBERTON WOOD, both of
The Salford Iron Works, Manchester, in the County of Lancaster, Electrical
Engineers, 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 :-
Our invention relates to the construction and arrangement of electrical controlling
switches in such a manner as to prevent sparking or the existence of an electric

page_text: arc in the neighbourhood of any of the contacts, as we shall describe referring to
the accompanying drawings.
Fig. 1 is a vertical section of a controlling switch according to our invention.
Fig. 2 is a plan of the contacts.
Fig. 3 is a section and Fig. 4 a plan shewing a modified form of the switch.
Referring first to Figs. 1 and 2, K is a base of non conducting material, such,
for instance, as slate, having fixed in it a central pin E of iron or steel, on which
the contact arm D can be turned by a hand wheel and forked spindle L.
The forks of L are insulated from the arm D which is of iron or steel carrying
the switch arm A consisting of a number of copper or brass strips bent at the ends.
Instead of the hand wheel and forked spindle L, a handle of other convenient form
may be fixed to the arm D insulated therefrom.
On the lower end of the pin E is fitted an iron or steel plate M which is fixed
by iron or steel bolts F to an iron or steel plate G. On this plate are fixed the
insulated contacts B of which 5 are shewn. These may be of copper or brass, or
they may be of iron or steel preferably coated with copper brass or carbon.
The central pin E is surrounded by a coil N which may form part of the main
circuit or be in a shunt therefrom. The current passing through the coil N
magnetises the plate M bolts F and plate G so that they constitute one limb, and
the pin E and arm D so that they constitute the other limb, producing a powerful
magnetic field at the contacts B, so that, if any arc were formed, it would be
immediately blown out.
As shewn in Figs. 3 and 4, in which parts corresponding with those in Figs. 1
and 2 are marked by similar reference letters, only one end of the contact arm is
made up of brass or copper strips A attached to the iron or steel bar D, the other
end, which passes over the contacts B, carries a block C of carbon or of carbon
coated with copper or brass pressed down by an adjustable spring S. In this case
the plate G is extended so as to embrace the pin E and the coil N rests upon it.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. An electric controlling switch of which the contact arm, the pin on which it
turns, and the plate carrying the contacts are made of iron or steel and constitute a
magnetic circuit which is excited by the current passing through a coil surrounding
the central pin producing a powerful magnetic field at the contacts tending to
blow out any are formed there, substantially as and for the purpose set forth.
2. The electric controlling switch, constructed and operating substantially as
described with reference to Figs. 1 and 2.
3. The modified electric controlling switch, substantially as described with
reference to Figs. 3 and 4.
Dated this 18th day of October 1895.
ABEL & IMRAY,
Agents for the Applicants.