Improvements in Safety Devices for Electrical Circuits.
Year: 1894

page_text: Date of Appl cation. 18th Jan., 1894
Complete Specification Left, 12th Oct., 1894-Accepted, 17th Nov., 1894
PROVISIONAL SPECIFICATION.
Improvements in Safety Devices for Electrical Circuits.
We, ALBERT ESSINGER, of 19 Clifton Hill, St. John's Wood, in the County of
Middlesex, Merchant, and THOMAS HARDEN, of 5 Rosslyn Villas, Delamere
Road, Wimbledon, in the County of Surrey, Electrical Engineer, do hereby
declare the nature of this invention to be as follows:-
This invention relates more particulary to safety devices for use in cases where
a high tension is reduced through a transformer to a low tension circuit; but it
will be seen from the description of the nature of the invention as hereinafter set
forth that the device may be employed in connection with other branches of
electrical work. When a high tension is reduced to a low tension circuit by means
of a transformer it is frequently desirable, if not absolutely necessary, that, should
by any chance the high tension pass to the low tension wires, the current should be
conducted at once to earth and not pass through the low tension system.
According to this invention it is proposed to make this connection in the
following manner: Connected with the return, middle, or balancing wire of the low
tension circuit is a sparking point set opposite to a sparking point connected with
earth. Between these two points is placed a fusible wire, or plug, one end of
which is attached to a spring arm carrying a catch which engages with a corre-
sponding catch on a contact maker normally held out of contact position. The
contact maker is operated when the plug or wire is fuzed, by a spring or weight
action which causes it to make a partial turn and complete the direct circuit from
the low tension return middle or balancing wire to earth and in the course of this
movement it also brings together two additional contact pieces which are in
connection with an electric battery and operate a bell, telephone, or other
signal.
The operation of the device is as follows, it being understood that so long as no
high tension current passes directly to the low tension system the parts remain in
their locked position. If now a high tension circuit passes to the low tension
system there is immediate sparking between the connection to the return, middle
or balancing wire and to earth. The arc formed between the points instantly fuses
the fusible plug or wire releases the spring catch which in turn releases the contact
maker which turns so as to make direct contact between the low tension wire and
earth and at the same time completes the battery circuit and operates the bell,
telephone, or other signal showing that the high tension circuit is passing to the
low tension system, (although instead of traversing same it is taking the line of
least resistance and passing directly to earth).
Dated the 17th day of January 1894.

page_text: COMPLETE SPECIFICATION,
Improvements in Safety Devices for Electrical Circuits.
We, ALBERT ESSINGER of 19 Clifton Hill, St. John's Wood, in the County of
Middlesex, Merchant, and THOMAS HARDEN of 5 Rosslyn Villas, Delamere
Road, Wimbledon, in the County of Surrey, 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:-
This invention relates more particularly to grounding or safety devices for use
in cases where a high tension current is reduced through a transformer to a low
tension current; but it will be seen from the description of the invention as
hereinafter set forth that the device may be employed in connection with other
branches of electrical work. When a high tension current is reduced to a low
tension current by means of a transformer it is frequently desirable, if not
absolutely necessary, that, should by any chance the high tension current pass to
the low tension wires, the current should be conducted at once to earth and not
pass through the low tension system.
According to this invention it is proposed to effect this in the following mauner,
reference being made to the accompanying drawings which form part of this
Specification, and in which :-
Fig. 1 is a plan view of the apparatus with the cover removed.
Fig. 2 is a side elevation looking in the direction of the arrow A, the side of
the cover being removed.
Fig. 3 is a side view looking in the direction of the arrow B, with the side
of the cover removed, and
Fig. 4 is a view looking in the direction of the arrow C, the side of the
cover being removed.
Connected with the returu, middle, or balancing wire 1 of the low tension
circuit D, is the post 2 carrying a sparking arm 3 set opposite to a sparking arm 4
which through post 5 is connected to earth E.
Between these two points on arms 3 and 4 is placed a fusible wire 6, one end of
which is attached to post 7, and the other end to pivoted post 8 operated by
spring 9. The post 8 carries a catch 10 which holds arm 11 of contact maker or
indicator 12 mounted on shaft 13 against the action of spring 14 so long as the
wire 6 is not fused the indicator being, when set, in the position most clearly seen
in full lines in Fig. 3, in which position it can be seen through the sight opening 15
in the cover F that the apparatus is set and ready to act. When wire 6 is fused
or if it breaks, the action of spring 9 causes post 8 to fly back and catch 10
releases arm 11, so that indicator 12 is by spring 14 drawn down to the position
shown in dotted lines in Fig. 3, and presses down contact spring 16 (most clearly
shown in Fig. 1) which completes a circuit 17 and 18 to a bell or indicator G.
Shaft 13 also carries a contact arm 19, and as the shaft turns, this arm makes,
contact between plates 20 and 21 which thus gives direct electrical connection
between the low tension circuit 1 and earth E. To provide for static currents
there is a permanent connection between the low tension system and earth by
means of support 22 (Figs. 1 and 2) which carries a sheet of black leaded glass 23,
or other material capable of carrying static currents to post 5 and thence it passes
to earth. The operation of the device is as follows, it being understood that so
long as no high tension current passes from H directly to the low tension system D
the parts remain in their locked position. If now a high tension current passes
to the low tension system there is immediate sparking between the sparking
arms 3 and 4. The arc formed between the points instantly fuses the fusible
wire 6 when post 8 flies back and releases the spring catch 10 from arm 11, and

page_text: the turning of shaft 13 causes the contact maker 19 to turn so as to make direct
contact with plates 20 and 21, and thus between the low tension wire 1 and earth E
and at the same time the indicator 12 completes the circuit 17 and 18 and operates
the bell or other signal G, showing that the high tension current is passing to the
low tension system, although instead of traversing same it will of course take the
line of least resistance and pass directly to earth.
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 :-
1. In a grounding or safety device for electrical circuits the combination of
sparking points, a fusible wire, a catch mechanically held by said wire, a contact
arm held by said catch, and contacts adapted to complete the circuit from a low
tension system to earth, substantially as set forth.
2. In a grounding or safety device for electrical circuits the combination with
the sparking points and fusible wire, of a catch mechanically held by said wire, a
contact arm, and contacts co-operating therewith, adapted to put the low tension
circuit to earth, and an indicator operated by the contact arm adapted to complete
a bell or like circuit, substantially as set forth.
3. In a grounding or safety device for electrical circuits the combination of the
sparking points, a fusible wire, a spring catch mechanically held thereby, an arm
held by the catch, a shaft carrying said arm, and also a contact arm, contacts
co-operating with the latter, and an indicator, substantially as described.
4. In a grounding or safety device for electrical circuits the combination of the
sparking points, a fusible wire, a spring catch mechanically held thereby, an arm
held by the catch, a shaft carrying said arm and also a contact arm, contacts
co-operating with the latter, an indicator, and a bell or like circuit adapted to be
closed by said indicator as set for
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Chartered Patent Agent,
For the Applicants.