Improvements in Electric Safety Appliances.
Year: 1899

page_text: Date of Application, 20th Feb., 1899
Complete Specification Left, 12th Oct., 1899-Accepted, 6th Jan.. 1900
PROVISIONAL SPECIFICATION.
Improvements in Electric Safety Appliances.
We, FRANKLIN HODGKINS BADGER, Superintendent, of No. 2775, St. Catherine
Street, in the City of Montreal, in the District of Montreal and Province of
Quebec, Dominion of Canada, and WILLIAM JOHN PLEWS, Electric Inspector,
of No. 350, Sherbrooke Street, in the said City of Montreal, do hereby declare
the nature of this invention to be as follows:-
This invention relates to electric safety switch devices whereby high tension
currents are prevented from injuring any apparatus, or wiring, arranged for
low tension currents in the event of the high tension current accidentally reaching
such apparatus, or wiring.
The invention consists in adapting the customary hand switch to automatically
open upon being released through the action of an electro-magnetic device operated
only upon the passage of a high tension current across a spark gap, or spark gaps,
arranged in a protective circuit which includes the points of the spark gap, or
gaps, the electro-magnetic device and an earth connection, the high tension
current, when an accident happens, reaching the protective circuit through the
switch proper, but acting instantly to open the switch and thus completely dis-
connecting the entire local circuit including the operating device itself and the
protective circuit from the main circuit, or supply wires.
A secondary feature of the invention consists in providing a testing key or
testing keys adapted to bridge the spark gap, or gaps, so that the ordinary low
tension service current may be sent through the protective circuit to shew
whether or not such circuit is in operative condition while a third feature consists
in the particular construction of the electro-magnet.
The transformer in connection with which we describe our invention, com-
prises, a high tension current wire and a low tension current wire these wires
being generally in such proximity that there is always a possibility of the high
tension current from such high tension wire, or other sources. accidentally escaping
to, or reaching, the low tension system and local circuit apparatus supplied thereby,
and it is the object of this invention as before mentioned, to prevent such high
tension current, if it should so come into connection with the low service system
reaching and damaging local wires, or apparatus, included in the service system.
The switch terminals of the main supply wires are connected therewith through
binding posts and terminal contacts are provided for the local, or installation,
circuit wires connected therewith through binding posts, the switch for con-
necting such terminals being formed, as usual, of pivotted metal arms, an in-
sulating cross bar connecting such arms, and a handle. The arms are pivotted
upon pivot pins secured to a base of slate, or other insulating material, and
insulated from the various other parts which are carried by the said base.
Thus far the parts described are those of the ordinary, and well known, hand
switch, and we will now explain what we consider to be the best arrangement
of elements and devices for carrying out our invention although we do not con-

page_text: fine ourselves to the particular details described as modifications may be made
without departing from the nature of our invention.
The pivot pins of the switch arms are extended sufficiently on either side to
accommodate the windings of double torsional springs bearing beneath the said
pivotted arms of the switch, and tending to throw them out of contact with the
main and local circuit terminals when the switch is released by the operation of
the electro magnetic device.
Our improved electro-magnet consists of a soft metal core having two inde-
pendent coils wound thereon.
One coil is wound upon the core from the middle thereof to one end and the
other coil is also wound on the core from the middle to the opposite end thereof.
This electro magnet is carried by, and insulated from, a bracket mounted upon
the base; an armature is pivotted to a plate carried by the base; a trip lever is
also pivotted to a plate carried by the base and presenting a bevelled toe-end to
engage a projecting lip on the armature and a hook, near its fulcrum, to engage
a hook on the cross bar connecting the switch arms.
The wires of the coils of the electro-magnet are connected together at one
end to the base of the post bracket for supporting the said magnet while a wire
leads from the said bracket to any suitable ground terminal, and other wires lead
from the opposite ends of the electro-magnet coils to independent insulated posts.
These independent posts are situated a short distance from, and face, the outer-
most of the posts of the bearing brackets in which the switch arms are pivotted,
and each independent post carries an adjusting screw provided with a set-nut for
regulating the length of a spark gap extending between the end of each screw
(furnished with a platinum point) and a similar point projecting from each
independent post.
In operation, should a high-tension current from its wire, or any other source,
reach the low tension wire, by defective insulation, or otherwise such high tension
current will pass, by either one, or both, of the switch arms. and jump the spark
gap, or gaps and proceed through the electro-magnets to the earth, thus energiz-
ing the magnets operating the armature so as to release the trip lever, and,
through it, disengaging the hook on the cross-bar of the switch, so that the
arms are thrown out of contact with the terminals and all current disconnected
from the local circuit and installation.
As a means of testing whether or not the service system is in proper condition
as regards insulation, and also incidentally to determine the working condition
of the device, press-buttons may be arranged with one end of their flexible metal
portions connected with the before mentioned outermost posts of the bearing
brackets and the other ends adapted to be pressed into contact with the independent
posts thus bridging the spark gap, or gaps, when if the insulation of the service
system be imperfect the low tension current will pass through the magnet, or
magnets, opening the switch and thereby indicating any such defect.
Dated this 20th day of February 1899.
Improvements in Electric Safety Appliances.
We, FRANKLIN HODGKINS BADGER, Superintendent, of No. 2775, St. Catherine
Street, in the City of Montreal, Dominion of Canada, and WILLIAM JOHN PLEWS,
Electric Inspector, of No. 350, Sherbrooke Street, in the said City of Montreal,

page_text: 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 follow-
ing statement:-
This invention relates to electric safety devices whereby high-tension currents
are prevented from injuring any apparatus or wiring arranged for low-tension
currents in the event of the high tension current accidentally reaching such
apparatus or wiring.
The invention consists in providing means whereby the customary hand-
switch is caused to automatically open, upon being released through the action
of an electromagnetic device operated only upon the passage of a high tension
current across a spark-gap or spark-gaps arranged in a protective circuit which
includes the points of the spark-gap or spark-gaps, the electro magnetic device,
and an earth connection; the high tension current, when an accident happens,
reaching the protective circuit through the switch proper, but acting instantly
to open the switch, and thus completely disconnecting the entire local circuit
including the operating device itself, and the protective circuit from the main
circuit or supply wires.
A secondary feature of the invention consists in providing a testing key or
testing-keys adapted to bridge the spark gap or gaps so that the ordinary low-
tension service current may be sent through the protective circuit to shew
whether or not such circuit is in operative condition; while a third feature
consists in the particular construction of the electromagnet.
In order that our invention may be clearly understood we will describe the
same with reference to the accompanying drawings of which—
Figure 1 is a diagram illustrating an arrangement according to our invention;
Figure 2 is a front elevation of the switch with safety devices in connection
therewith;
Figure 3 a vertical section of the same shewing the switch closed and
Figure 4 is a side elevation shewing the switch open.
1 represents a transformer in which, as is generally arranged, a high tension
current wire 2 and low tension current wire 3 are in such proximity to each
other that there is always a possibility of the high tension current from such
high tension wire or other sources accidentally escaping to, or reaching the low-
tension system and local-circuit apparatus supplied thereby, and it is the object
of this invention, to prevent such high tension current, if it should so come into
connection with the low service system, from reaching and damaging all the local
wires or apparatus included in the service system.
5 are the switch terminals for the main supply wires 3, which wires are con-
nected thereto by binding posts 6, and 7 are the terminals for the local or in-
stallation circuit wires 8, which are connected thereto by binding posts 9. The
switch for connecting the terminals 5 and 7 is formed as usual, of pivoted metal
arms a connected together by an insulating cross-bar b provided with a handle c.
The arms a are pivoted upon pins d in supports e el standing up from the bases
of the terminals 7 but insulated therefrom and the various other parts are carried
by the base f which may be of slate or other insulating material.
Thus far the parts described are those of the ordinary and well known hand-
switch, and we will now describe in connection therewith an arrangement of
elements and devices for carrying out our invention premising however that we
do not restrict the invention to the particular details shewn, and described as
various equivalents and modifications of the same may be employed without
departing from the nature of our invention.
The pivot pins d of each of the switch arms a is extended sufficiently on both
sides of the arm to accommodate between the said arm and the supports e e¹,
the windings of torsional springs g which by bearing beneath the pivoted arm a
tend to throw the said arm out of contact with the main and local circuit terminals
when the switch is released by the operation of an electro-magnetic device as

page_text: next described. The improved electro magnetic device comprises an electro
magnet of novel construction consisting of a soft metal core 20 having two inde-
pendent coils 21 and 22 wound thereon. The coil 21 is wound upon the core
from the middle thereof to one end, and the coil 22 is also wound on the core
from the middle to the opposite end thereof.
The electro magnet is carried on a support or post secured to the base f
from which it is insulated by a piece h¹. The armature is pivcted at k to a
plate m carried by the base fa trip lever a being also pivoted to a plate o secured
to the base f, the said trip lever having a beveled end p to engage a projecting
lip on the armature, and a hook r near its fulcrum to engage a hook s on the
cross bar to which the switch-arms a a are attached.
The two coils 21, 22 of the electromagnet are connected at one end by wires w
to the post 2 while a wire leads from the post h² to any suitable ground-
terminal w. Other wires y lead from the opposite ends of the electro magnet
coils 21, 22 to insulated posts which are arranged at a short distance from.
and face the supports e¹ in which the switch arms a a are pivoted. Each post z
carries an adjusting screw 10 having a platinum point 13 and provided with
set-nut 11 for regulating the length of a spark-gap 12 extending between the point
of each screw and a similar point 14, projecting from each post e¹.
Should a high tension current from the wire 2 or any other source reach the
low tension wire 3 by defective insulation or otherwise, such high tension current
will pass through either one or both of the switch-arms a to the spark-gaps 12
jump the same and proceed by wires y through the electromagnet to the earth
terminal w. The magnet being thus energised operates the armature j so as to
release the trip-lever and through it, disengage the hooks on the cross-bar b
of the switch, so that the arms a are thrown out of contact with the terminals 5,
7 (as shewn, in Figure 4) and thus disconnect the current from the local circuit
and installation.
As a means of testing whether the service system is in proper condition as
regards insulation and also incidentally to determine the working condition of
the device, press-buttons 15, 15 may be arranged as shewn with one end of their
flexible metal connections 16 secured to the posts e¹ and the other ends adapted
to be pressed into contact with the posts z thus bridging the spark-gaps. If the
insulation of the service system is imperfect, the low tension current will pass
through the magnet or magnets thereby opening the switch, and indicating any
such defect.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed we declare that what
we claim is: -
1. In an electric safety appliance the combination with a main circuit and a
local circuit separated one from the other, of a spring operated switch, adapted
to connect the flow and return wires of the said separated circuits, and a protective
circuit, separated from the local circuit by a high resistance medium, and con-
taining electromagnetically-operated means for automatically releasing the switch
the said means comprising independent magnetic coils operating upon a common
trip, whereby the local circuit, including the operating device itself and the pro-
tective circuit, is disconnected from the main circuit substantially as hereinbefore
described.
2. In an electric safety appliance the combination with a main circuit and a
local circuit separated one from the other, of a switch adapted to connect the flow
and return wires of the said separated circuits, of means for retaining the said
switch in connection with the circuits, means for disconnecting the switch from
the circuits and a protective circuit, separated from the local circuit by a spark-
gap and containing an electro-magnetic device adapted to operate the switch-
retaining means, whereby the said switch may be released from contact with

page_text: said circuits, and means for shunting current from the local circuit through the
electromagnetic device substantially as herein before described.
3. An electric safety appliance, comprising a main circuit, a local circuit to
be protected, the said circuits being separated one from the other, switch arms or
levers normally connecting the flow and return wires of the circuits, a trip lever
and detent mechanism for retaining the switch arm or lever in contact with the
flow and return wires, springs tending to throw the switch arms or levers out of
contact with the flow and return wires, and an insulated protective circuit, in-
cluding therein in a ground circuit, an insulated electromagnetic releasing mechan-
ism for the trip lever, the said mechanism consisting of magnetic coils in separate
circuits operating upon the common trip, separated from the local circuit by a
spark gap or gaps, which may be jumped by the current flowing from the main
circuit to and over the said local circuit through the switch arm or lever, when
increased in tension above a predetermined low degree, thereby operating the
said electro-magnetic mechanism to cause the switch arms or levers to completely
separate the local and protective circuits from the main circuit substantially as
hereinbefore described.
Dated this 12th day of October 1899
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.