An Improved Automatic Safety Device specially applicable to Three- wire or Balanced Systems of Electrical Distribution generally.
Year: 1898

page_text: Date of Application, 28th July, 1898
Complete Specification Left, 28th Apr., 1899-Accepted, 2nd June, 1899
PROVISIONAL SPECIFICATION.
An Improved Automatic Safety Device specially applicable to Three-
wire or Balanced Systems of Electrical Distribution generally.
Messrs. VERITYS LTD., Electrical Engineers, of Plume Works, Aston, Birming-
ham, in the County of Warwick, and LOUIS JOHN STEELE, Electrical Engineer, of
14, Clarendon Road, Holland Park, London, in the County of Middlesex, do
hereby declare the nature of this invention to be as follows:-
The blowing of a fuse or accidental disconnection of the neutral wire on a
three wire system or other balanced system of electrical distribution, would cause
an undue and dangerous rise of potential on the least loaded side or sides of the
system, should the system be appreciably unequally loaded. To obviate such risk
to property and to any lamps or apparatus connected to the system, we employ a
device which shall be operated automatically on the blowing of the fuse of the
neutral wire or wires or the accidental disconnection of same; the device immedi-
ately disconnecting the circuits from the source of supply. According to our
invention we provide a device which may be of any convenient design applicable
to any form of single or multi-pole switch for accomplishing the above object. In
one form of our invention we employ a solenoid or solenoids connected as a shunt
to the neutral fuse or fuses: on the blowing of the latter, the solenoid will attract
the armature, and in so doing release the switch.
In another form of our invention we employ a system of differential solenoids
so connected to the outer circuits as to cause the switch or switches to open when
there is an appreciable difference between the voltages of the outer circuits.
In another form we may cause the actual blowing of a neutral fuse, to release a
switch or switches either directly, or by means of a detent or equivalent device.
Dated this 22nd day of July 1898.
LOUIS JOHN STEELE.
VERITYS LIMITED.
GEO. H. VERITY,
COLES. L. HARRIS,
Directors,
W. NICHOLSON, Secretary.
An Improved· Automatic Safety Device specially applicable to Three-
wire or Balanced Systems of Electrical Distribution generally.
We, VERITYS LIMITED, Electrical Engineers, of Plume Works, Aston,
in the County of Warwick, and LOUIS JOHN STEELE, Electrical Engineer, of
14, Clarendon Road, Holland Park, London, do hereby declare the nature of this
DR77

page_text: 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 relates to those systems of electrical distribution known as the
EC three-wire" or balanced systems, and consists in the employment in connection
therewith of safety devices, as hereinafter described, which are automatically
brought into operation instantly anything accidentally or otherwise happens to the
connections, or the fuse of the neutral conductor or conductors, should, at the
same time, the sides of the system be so unequally loaded as to produce a dangerous
increase of electrical potential on the least loaded side. The device according to
this invention comprises, as one of its parts, a single or multiple switch of a
convenient design which, immediately anything happens to the connections of
the neutral conductor, or its fuse, blows and disconnects the circuits from the
source of an electric supply.
The characteristic features of the device according to this invention are, in one
form, a fuse and an electro-magnet or a solenoid coupled to the neutral conductor, a
single or multiple switch connected within the circuits of the system so as to open
and close them, and holding and releasing devices for the said switch which inter-
vene between the electro magnet or solenoids armature. In another form a system
of differential solenoids is connected to the outer circuits so as to cause the switch
to be operated, through the holding and releasing mechanism, to open the circuits
when there is an appreciable difference between the voltages of the system.
It will be obvious that the safety device according to this invention can have
its parts or essential features arranged in various ways with the same working
result in order to adapt it to different forms of the particular class of electrical
distribution, and that therefore, in the accompanying sheet of drawings, dia-
grammatical views of the invention are shown. These drawings show two forms of
the invention in Figs. 1 and 2 applied to a three-wire" system, whilst a
variation is shown in diagram in Fig. 3, the electro receptive devices in the
circuits being shown in diagram as lamps and the circuits of unequal load:
In Fig. 1 the conductors a, a, of the outer circuit, and also the neutral con-
ductor, are fitted with a multiple switch e, which is adapted to make and break
the circuits simultaneously and at one operation; switch arms
thereof,
suitably jointed at e, being coupled by a link and arranged so that their contact
tips engage spring contacts, in the different conductors. This multiple
switch is operated, when released, to open the circuit by a spring or its equiva-
lent d, its action being a fly one, and it is operated by hand to close the circuits
through handles d, in which position it is held by a detent e which is under
the influence of a solenoid 7 connected as a shunt to the fuse h arranged along the
neutral conductor. This solenoid has a high resistance in comparison to the fuse h
so that nearly the whole of the current in the circuit passes through the fuse so
long as it is intact. The detent e is shown as a hinged catch connected to the
armature of the solenoid, and engaging a projection upon one of the arms of the
switch when the said switch closes the circuits, so that the said switch is held to
close the circuit against the action of the spring d by the said catch, until such
time as the fuse blows, or some part of it becomes disconnected, whereon the
armature of the solenoid y lifts the catch from holding the switch, which latter
immediately and automatically flies off and opens the circuits.
The catch e is capable of being operated by hand. m are the dynamos or sources
of electric supply. n are the lamps arranged on the sides of the system to form
an unequal loud.
In Fig. 2 the solenoid 9 is differentially wound, and one half is connected to one
side of the system and the other half to the other side of the system; the electrical
energy in the windings, under normal conditions, balancing. Should the system
be unequally loaded with lamps, as shown, or with other electro-receptive devices
or instruments, and the fuse on the neutral conductor be blown, or this con-
ductor be disconnected, then the electrical conditions of the one half of the

page_text: winding would be stronger than the other half, owing to the voltage on the one
side of the system being greater than on the other side of the system, and the
armature g, which operates the detent e, will be moved so as to free the switch
in the manner before described; the said switch being operated and controlled
directly in the same manner as in the arrangement, Fig. 1.
In Fig. 3 the switch c is held to close the circuits by a catch lever i connected to
the neutral conductor, and whose one end carries the one end of the fuse h; the
last named being kept taut by a spring which, on the fuse blowing, will cause
the lever i to free the switch arm it holds.
By this invention is obviated considerable risk to property and damage to any
lamps or electro-receptive apparatus arranged on an unequally loaded side of a
balanced system of distribution through the blowing of the fuse, or the accidental
disconnection of the neutral conductor or wire.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that
what we claim is:-
First. In "three-wire" or balance systems of electrical distribution, auto-
matically protecting the circuits and electro-receptive devices within them by
fitting to the system fly-off switches for opening and closing the circuits, solenoids,
or their equivalents, brought into effective operation by the undue rise of voltage
on one side of the system caused by the blowing of the fuse in the neutral circuit,
or the accidental disconnection of the neutral conductor carrying it, and holding
and releasing means to the switch, and which is operated to open the circuits by
the solenoid, for the purposes substantially as described.
Second. In "three-wire or balance systems of electrical distribution, the com-
bination of the neutral conductor and its fuse of a differential solenoid connected
in the circuits, a fly-off switch for opening and closing the circuits, and a holding
and releasing device to the switch which is operated by the differential solenoid,
for the purpose substantially as described.
W. P. THOMPSON & Co.,
11, Burlington Chambers, New Street, Birmingham,
Also of Liverpool, London, and Manchester,
Patent Agents for the Applicants.