Improvements in Electric Safety Fuses and in Electric Switches.
Year: 1890

page_text: Date of Application, 3rd July, 1890
Complete Specification Left, 3rd Apr., 1891-Accepted, 9th May, 1891
PROVISIONAL SPECIFICATION.
Improvements in Electric Safety Fuses and in Electric Switches.
I, JOSEPH DEVONPORT FINNEY ANDREWS of 41 and 42 Parliament Street,
Westminster in the County of London, Electrical Engineer, do hereby declare the
nature of this invention to be as follows:-
My invention relates to the construction of an electrical safety fuse which can be
used alone, or in conjunction with a switch. I provide a base of incombustible
insulating material which may be a disc or of other form, and in this base I form a
groove or hole to receive a length of fusible wire. In the base I form two holes
extending down from the face of the base into its body, but not through it, and
opening into the groove or hole in which is placed the fusible wire with its ends
extending into the two holes. I pour into the holes fusible metal or alloy so as to
form two conducting plugs cast on to the fusible wire. To these plugs I connect
the circuit wire when the fuse is to be used alone; or, when it is to be used in
conjunction with a switch, I make the fuse above described act as the base of the
switch presenting the two plugs for contact with the moveable part of the switch,
or I make the fuse itself the moveable part, its two plugs being moved to or from
fixed contacts.
Dated this 2nd day of July 1800
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
-
Improvements in Electric Safety Fuses and in Electric Switches.
I, JOSEPH DEVONPORT FINNEY ANDREWS of 41 and 42 Parliament Street,
Westminster, in the County of London, Electrical 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 :-
My invention relates to the construction of an electric safety fuse which can be
used alone, or in conjunction with a switch.
I provide a disc of incombustible insulating material grooved around its periphery
and having two holes in its face and extending down into its body more than half
its depth, these holes being at opposite ends of a diameter and opening into the
peripheral groove. I place in the groove fusible wire the ends of which extend into
the two holes, and I pour into the holes fusible metal or alloy so as to form two
conducting plugs cast on to the fusible wire. To these plugs I connect the circuit
wires when the fuse is to be used alone, or when it is to be used in conjunction with
a switch, I make the fuse above described act as the base of the switch presenting
the two plugs for contact with the moveable part of the switch, or I make the fuse
itself the moveable part, its two plugs being by its rotation moved to or from fixed
contacts.
Fig. 1 of the accompanying drawings is a section of a combined switch and safety
fuse. A B are the two conductors which the switch connects or disconnects, they
pass into the metal casing C, bedded in insulating material D and terminate in
contact pieces E F. A piece of incombustible insulating material G, shaped like
a grooved pulley, has in its groove a wire of fusible metal such as is used in safety
fuses, the ends of the wire being turned down into holes bored in G filled round
with molten fusible metal poured into the holes around the ends of the wire and
constituting two contact plugs H K. The piece G is held up by a spring L opening

page_text: the circuit of A. B. By turning a button M a pin P travelling in a sloping recess
of a piece N moves it down pushing down the piece G so as to bring H and Kin
contact with E and F. The circuit is thus completed through the wire lying in the
groove of G, and, if the current is excessive, the wire fuses opening the circuit
The wire, instead of lying in a horizontal groove of G may be in a vertical groove
as shewn in the side and end views Figs. 2 and 3.
Obviously the mode of moving the piece carrying the fusible wire or strip may be
varied and the position of the contacts H K in relation to E F, as the circuit might
be opened by turning the contact pieces aside horizontally as well as by raising
them vertically.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. An electric safety fuse consisting of a wire or strip of fusible metal laid in the
groove of a piece of incombustible insulating material with its ends inserted in holes
of the piece, filled in with plugs of fusible metal cast therein, substantially as
described.
2. In combination with an electric switch a safety fuse arranged to form part of
the conductor connecting the contacts of the switch when the circuit is closed,
substantially as described.
Dated this 3rd day of April 1891.
ABEL & IMRAY,
Agents for the Applicant.