Improvement in Electric Switches.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvement in Electric Switches.
I, OTTO CLAUDE IMMISCH, of 102, Tollington Park, London, N., Electrician, do
hereby declare the nature of this invention to be as follows:-
The present invention is applicable to electric switches generally and has for
its object to prevent injurious sparking at the switch connections, when the
contact is broken for the purpose of either changing the connections or breaking
the circuit. For this purpose when the switch is actuated, before the existing
connections are broken the contact piece of the switch is first caused to establish
a connection by which a path for the current is established through an electro-
magnet, which as soon as it is excited is drawn into its helix, which movement
as provided for in this invention breaks the main circuit.
The spark which is thereby established occurs, therefore, not in the switch
itself where it is apt to do damage, but at that place where the automatically
movable electro-magnet is placed, which may be at any easily get-at-able point
as long as it forms part of the main circuit.
Dated this 3rd day of February. 1898.
ALLISON BROS.,
Agents, for the Applicant.
I, OTTO CLAUDE IMMISCH, of 102, Tollington Park, London, N., 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: --
This invention has for its object the prevention of injurious sparking in a
switch when the contact is broken in order either to change the connections or
to break the circuit.
For the purpose of this invention the movable switch-arm carrying the current
is made in two parts, insulated from each other and so disposed with regard to
the fixed contacts that when one part of the switch-arm breaks the working
contact, the other part of the said switch-arm lags behind. The two parts being
insulated from each other are joined through the coil of an electromagnet having
a movable core. The core under ordinary working conditions forms part of the
main circuit. When the first mentioned part of the movable switch-arm is
moved away from the fixed contact piece the current passing round the magnet
[Price 8d.]

page_text: becomes established, and as the whole available E.M.F. acts on it the magnetic
core is powerfully drawn within its helix thereby breaking the main circuit.
The spark which is thus occasioned does, therefore, not take place in the switch
itself but may be shifted to any other convenient part of the circuit where it
can do no harm.
Figs. 1 and 2 of the accompanying drawing illustrate a suitable form of switch
for carrying out my invention, and in such figs., the switch-arm is depicted in
that position where the first part of the movable switch-arm E¹ has left the
contact piece F, but E (which here is drawn as a disc) is still in connection
with F and forms the magnetic circuit through D, C, B, the spiral A back to H.
In this position of the switch-arm the contact would continue to be alternately
made and broken somewhat in the manner of an electric bell. The noise thus
occasioned would warn an attendant that proper working contact was not estab-
lished; in practice, however, no purpose would be served by having the switch
in this position, and the contact pieces being in general closer together than
shown in the drawing, the circuit as a rule is only broken once before it is estab-
lished again.
My aim has been to attain my object by a cheap and simple device quite as
efficient in its working as other costly and complicated devices hitherto employed
for the same purpose.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
The combination with a switch of a contact piece in addition to the ordinary
contact piece for making and breaking the circuit, and an electromagnet with
movable core suitably connected with such additional contact piece and the main
circuit, so that at the time the ordinary contact piece of the switch breaks the
circuit the additional contact piece lags behind and opens a path for the current
through the electromagnet, which current acting on the movable core draws the
latter into the helix surrounding it and thereby breaks the circuit and thus pre-
vents injurious sparking at the ordinary connections of the switch, all substan-
tially as specified.
Dated this 28th day of October 1898.
ALLISON BROS.,
Agents for the Applicant.