Improvements in Safety Switch Apparatus for Systems of Electrical Distribution.
Year: 1897

page_text: Date of Application, 6th July, 1897-Accepted, 7th Aug., 1897
COMPLETE SPECIFICATION.
Improvements in Safety Switch Apparatus for Systems of Electrical
Distribution.
I EUSTACE OXLEY, of 1242 11th Street, Northwest, Washington, in the District
of Columbia, United States of America, 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:—
In systems of electrical distribution in which a balance must be preserved, between
two or more sides of the system, the disturbance of the equilibrium which should
normally be preserved has been found to have an extremely detrimental effect upon
the translating devices. For example if the translating devices are lamps, a disturbance
of the normal balance usually causes destruction of some of the lamps, and even if
they escape destruction, they are strained so severely as to greatly lessen their
duration.
way.
The liability to a frequent occurrence of such results is a serious objection to any
system employing a balance wire, which is rendered useless when its safety fuse gives
Such removal of this wire from the system, unless it is followed by an
immediate opening of both sides of the circuit, is very apt to cause destruction of
more or less of the lamps upon the strained side of the system in a manner so
startling as to prejudice the public against the use of electricity.
It is the purpose of my invention to provide means of great simplicity and trifling
cost, whereby this objection may be fully obviated, as I shall describe referring to the
accompanying drawings.
Figure 1 is a side elevation showing a switch operating according to my
invention.
Figure 2 is a plan of the same; and Figure 3 is a diagram of the several circuits,
and connections to the switch.
The switch apparatus consists of a base plate 1, upon which is mounted an
electro-magnet 2 and a spring supported armature 3, facing the poles of the magnet.
The armature is supported upon a spring finger 4, having in its upper end a small
hole. Behind the armature is arranged a switch, which has three switch arms, 5, 6
and 7, pivotted upon separately insulated terminals, 8, 9 and 10, respectively. The
movable ends of the arms are connected by a cross-brace 12, having a handle 13,
and when the arms 5, 6, and 7 are down, they enter clips 14, 15, and 16,
respectively.
Upon the cross bar 12 is hung a finger 17, having a projecting pin 18, which
enters the hole in the upper part of the spring 4, thereby locking the switch-arms in
their clips holding them down in opposition to springs 19 coiled upon a yoke 20
curved to the arc of the circle in which the switch arins move when released. The
yoke passes through holes 21 in brackets 22 projecting from the transverse bar 12.
In Figure 3, I have shewn the switch connected in a three-wire system, in which F
indicates the main fuse block, 23 and 24 denote branches from opposite sides of the
system, the two side wires being connected to the clips 14 and 16, respectively, and
the balancing wire to the clip 15.
The electro-magnet 2 is of comparatively high resistance so that only a small

page_text: amount of current flows from the opposite sides of the balance wire fuse f, through
wires 25 and 26, to binding post 27, and thence around the cores of the magnet 2,
most of the current normally flowing over usual path. If however the fuse f should
give the sudden rise of voltage between the two points of connection of the wires 25
and 26 causes said current to flow through the coils of the magnet 2, as to energise
the magnet, and the armature 3 being attracted withdraws the spring support 4 from
the pin 18. The switch arms, being thus released are caused by the springs 19 to
rise out of the clips 14, 15, and 16 and mount to the position shewn in dotted lines
in Figure 1, thus completely cutting off from all connection with the mains that
portion of the system to which the switch is applied.
Although I have shewn the apparatus applied to a three-wire system, it may be
readily understood that it is applicable to other systems which have safety fuses
that can be connected to the coils of a releasing magnet as described with reference to
the fuse f.
Having now particularly described and ascertained the nature of this
invention, and in what manner the same is to be performed, I declare that what
I claim is
In a system of electrical distribution a switch normally held against spring pressure
in position to close the circuits by the armature of an electro-magnet baving a coil
of comparatively high resistance, connected to the opposite ends of a safety fuse so
that when the fuse gives 'way the magnet is energised attracting its armature,
and releasing the switch which thereupon opens the circuit substantially as set
forth.
ABEL & IMRAY,
Agents for the Applicant.