Improvements in Devices for Breaking Electric Circuits and Protecting the same from Excessive Currents.
Year: 1899

page_text: Date of Application, 19th June, 1899
Complete Specification Left, 2nd Mar., 1900-Accepted, 7th Apr., 1500
[Communicated from abroad by THE ROLFE ELECTRIC COMPANY, of 355, Wells
Street, Chicago, Illinois, United States of North America, Manufacturers.]
Improvements in Devices for Breaking Electric Circuits and
Protecting the same from Excessive Currents.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 322, High Holborn, in the County of Middlesex, 6, Lord
Street, Liverpool, and G, Bank Street, Manchester, both in the County of Lan-
caster, and Lower Temple Street, Birmingham, in the County of Warwick, Civil
Engineer, do hereby declare the nature of this invention to be as follows:-
The invention relates to devices which are employed upon low tension electrical
circuits for the purpose of protecting those circuits and the instruments thereon,
such as telephones, telegraph apparatus and the like, from the dangerous and
injurious effects of unduly strong currents and excessively high potentials.
The object of the invention is to provide a simple, practical, inexpensive,
durable and reliable device of the class specified. To the attainment of this and
other desired ends, the invention consists in matters hereinafter set forth.
The invention contemplates the opening or breaking of the circuit by the
automatic actuation of a circuit-breaking device.
As a preferred arrangement this circuit-breaking device consists of a section
of conductor forming a part of the circuit, and it is actuated in such a way and
to such an extent as to cause the bodily removal of such section of circuit conductor
from the circuit.
This circuit-breaking device may be in the form of a plug sliding between and
making contact with a couple of metallic contacts; or in the form of a couple of
metallic plugs or rods, mechanically connected together and arranged to fit into
separate or individual metallic sockets or terminals.
The circuit-breaking device is normally subjected to the force of a spring or
equivalent pressure-exerting device, which tends to normally actuate it so as to
cause it to break or open the circuit.
The circuit-breaking device is held against the action of the spring by a device
capable of acting or operating upon the passage in the circuit of an unduly strong
current or an excessively high potential.
This excess operated device holds the spring in equilibrium under normal
circumstances, but when the strong current passes in the circuit the excess-
operated device is actuated, and upon operating releases the spring, which auto-
matically acts upon the circuit-breaking device and opens or breaks the circuit.
In case the circuit-breaking device consists of a section of bodily removable
conductor, it is apparent that this section of conductor will be removed and a
wide gap thereby formed in the circuit. The formation of this gap absolutely.
prevents the sparking or arcing of the current across the terminals.
While the excess operated device could be of any desired construction, it is

page_text: preferably a heat coil composed of a small mass or button of fusible material and
a section of high resistance wire embedded in this fusible material. When an
unduly strong current passes through the circuit the high resistance wire becomes
heated and thereby melts, or softens or fuses the mass of fusible material.
In the preferred embodyment of the invention, two circuit-breaking devices,
each consisting of a pair of separated metallic plugs or rods, are mounted upon a
suitable insulating base. These two devices are connected in the opposite sides
of the circuit, which it is proposed to protect. Either one or both of them will
operate upon the intrusion of an unduly strong current, or an excessively high
potential upon the line.
There is also mounted upon this base a lightning arrester consisting of three-
carbon blocks, two of which are connected with the opposite sides of the line,
while the third one is connected with the ground, and is positioned between the
. other two. All of these carbon blocks are coated with shellac, or other similar
adhesive and insulating substance, which prevents dust or particles of carbon
from coming into contact with the carbon blocks and thereby interfering with
the proper operation of the lightning arrester.
The device is simple and reliable in its operation, and affords adequate and
effective protection from the dangers mentioned.
101
1000
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.
Improvements in Devices for Breaking Electric Circuits and
Protecting the same from Excessive Currents.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 322, High Holborn, in the County of Middlesex, 6, Lord
Street, Liverpool, and 6, Bank Street, Manchester, both in the County of Lan-
caster, and Lower Temple Street, Birmingham, in the County of Warwick, Civil
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 devices which are employed upon low tension electrical
circuits for the purpose of protecting those circuits and the instruments thereon,
such as telephone, telegraph apparatus and the like, from the dangerous and
injurious effects of unduly strong currents and excessively high potentials.
The object of the invention is to provide a simple, practical, inexpensive,
durable and reliable device of the class specified. To the attainment of this
and other desired ends, the invention consists in matters hereinafter set forth.
In the accompanying drawings,
Figure 1 is a plan view of a protector embodying my invention;
Figure 2 is a vertical section taken centrally through the same;
Figures 3 and 4 are modified forms;
Figure 5 is a vertical section taken centrally through Fig. 4:
Figure 6 is a perspective view of the preferred arrangement and mounting.of
the device; and
Figures and S are views of details of construction.
My invention contemplates the automatic opening or breaking of the current
when an unduly strong current strikes the line. This is done by means of a

page_text: circuit-breaking device A, which is arranged for movement and is adapted to
open or break the circuit when moved.
This circuit-breaking device can be of any suitable construction; but as a
preferred one it consists of a section of current conductor, which is arranged for
bodily removal from the circuit. It is apparent that by thus removing a section
of the 'circuit conductor from the circuit, a wide gap or opening is formed therein,
and sparking or arcing is absolutely and effectively prevented.
In Figures 1, 2 and 3 the circuit-breaking device A is in the form of a simple
metallic plug which is arranged to slide in and out of a suitable socket, formed
by the base piece B, and to make contact with a couple of spring contacts 1, 1,
secured to said base piece.
It will be seen that the end portion of the plug forms part of the circuit
between the two contacts, and that when it is removed it leaves a wide gap
between the latter.
The circuit-breaking device is subjected to a spring C, or equivalent device,
which normally subjects it to force, tending to actuate it so as to cause it to open
or break the circuit!
When the circuit-breaking device consists of a section of bodily removable
conductor, it will be seen that the spring C, or equivalent, will tend to auto-
matically remove this section of conductor bodily from the circuit.
In Figures 1, 2 and 3 the spring C is shown having one of its ends attached
to the outer end of the plug A, and its other end attached to the end of an arm 2,
which is secured to the base pièce B.
In this arrangement the spring C tends to normally pull or draw the plug
away from the base piece B and out from between the contacts 1, 1.
The circuit-breaking device A is held against the actuation of the spring C
by a device D, which is included in the circuit and is adapted to operate upon
the passage therein of an unduly strong current.
This excess operated device may consist of any well known or suitable device
capable of accomplishing this result.
In Figures 1 and 2 it consists of what may be called a heat coil. This is
composed of a mass or button 3, of waxy material, which is capable of softening
when heated, and a coil 4 of high resistance wire, which is in part embedded in
the button 3 and becomes heated so as to soften the button when the excessive
current passes through it.
The button 3 is engaged by a staple or eyelet 5 on the plug A, and is connected
with the base B by a loop 6 embedded in the button 3, and a hook 7 secured to the
base B.
Under normal circumstances the heat coil, consisting of the button 3, the coil
of wire 4 and the loop 6, holds the plug A in position to make contact with the
contacts 1, 1, against the action of the spring C.
When a strong current passes in the line, however, the button 3 is softened by
the heat generated in the coil.4, and the spring C is thereby released and allowed
to withdraw the plug A away from and out of contact with the contacts 1, 1.
In Figure 3 the excess-operated device I) consists of a section 8 of fusible
wire, and this has its end connected with screws 9, 9, on the base B, and engages
a hook 10 on the plug A. This section of fusible conductor 8 likewise holds
the plug. A normally against the action of the spring C, but releases it when
fused or melted by the unduly strong current.
It will be seen that in these two arrangements shown in Figs. 1 and 2 and 3,
the section of circuit conductor is normally subjected to force tending to remove
it bodily from the circuit, and that an excess-operated device normally holds the
section of circuit conductor in position to close the circuit against the action of
such force, and release such conductor when it is operated by an unduly strong
current.
In Figs. 4 and 5 the circuit-breaking device A¹ also consists of a plug, but in
this instance the plug is composed of two insulated metallic portions 11 and 12,

page_text: This
which contact with the spring contacts 1, 1. This plug is likewise subjected to
the force of the spring C, which sets against a collar 18 fixed on the plug, and
thereby tends to actuate the latter so as to open or break the circuit.
spring acts also against an abutment provided by a sleeve 14 surrounding the
plug and capable of sliding longitudinally thereon.
The removable sleeve 14 is held against actuation by the spring C by an' excess-
operated device, such as the heat coil shown, whose loop 6 engages a hook 15 on
the end of the sleeve 14, and whose button 3 is held in a socket 16 on the end of
the plug.
Under normal conditions the heat coil holds the sleeve 14 from being removed
from the spring C, but when the strong current passes in the line and the button 3
is softened by the heat of the coil 4, the sleeve 14 is released, whereupon it is
forced forwardly under the pressure of the spring and strikes the base B and
thereby throws the plug out of, or ejects it from its socket, so that it becomes
disconnected from the spring contacts or terminals 1, 1.
v
It will be seen that while in the arrangement shown in Figs. 1, 2 and 3 the
excess-operated device holds the plug or circuit-breaking device itself against
movement in the arrangement shown in Figs. 4. and 5 such excess-operated.
device forms a connection between the circuit-breaking device and the movable
or sliding abutment thereon. In both of them, however, the excess operated
device serves to normally hold in equilibrium the force exerted by the spring to
actuate the circuit-breaking device.
In Figure 6 is illustrated the preferred embodyment of a single instrument
involving my invention.
This instrument consists of a circular base B', having. mounted upon it two
circuit-breaking devices A2, A2, one for each side of the circuit. These circuit.
breaking devices A2, A2 operate in the same way as does that shown in Figs. 4
and 5, although their construction varies slightly from the construction of this
latter.
These devices A2, A2 comprise a couple of metallic rods 17, 17, held together
by a connecting cross piece or brace 18 secured to their upper ends.
The rods 17, 17 fit into metallic sockets secured in the base B'. They are
surrounded by coil springs 19, 19, which set against the connecting cross-piece 18
and also against an abutment or slide 20, which is arranged to slide upon the
rods 17, 17.
The movable abutment 20 is held against movement by a heat coil whose
button 3 is engaged by the connecting piece 18, and whose loop G is engaged by
a hook 21, secured to the abutment 20.
When the current in the circuit is normal, the devices A2, A2, stand upon the
base 13, as shown in Fig. 6; but when an unduly strong current passes in the
circuit, the button 3 is softened, as explained; the loop G is withdrawn from it,
and the springs 19, 19 are thereby released, whereupon they elevate the connect-
ing piece 18, and thereby withdraw or eject the metallic rods 17, 17 from their
sockets in the base B¹. In this way a wide opening or gap is formed in the
circuit.
In this instrument I provide a lightning arrester in the form of three carbon
blocks EE and F, for high potentials.
The blocks E, E, are connected to the opposite sides of the circuit and the
block is connected to the ground and is arranged between the blocks E, E.
These three carbon blocks are coated with shellac or similar adhesive and
insulating substance, in which way the particles of carbon are prevented from
separating from the blocks, and in which way also contact cannot be made between
them by particles of dust or the like.
These blocks E, E, and F are desirably provided with metallic rods similar to
the rods 17, 17 of the device A2, A2, and these, are fitted in metallic sockets in
the base B. By such arrangement they are made removable, and can be replaced
or repaired or removed for test purposes.

page_text: It will be seen that the devices embodying my invention are simple, inexpensive,
and afford ample and reliable protection against strong currents and high
potentials.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is;-
1-In a protective device for electric circuits, the combination of a section of
circuit conductor arranged for bodily removal from the circuit; means normally
subjecting the section of circuit conductor to force tending to thus remove it
bodily from the circuit; and means normally holding in equilibrium the force
to which the section of circuit. conductor is subjected, and operating upon an
excess of current in the line so as to free such force and allow it to remove the
section of circuit conductor from the circuit, substantially as set forth.
2 In a protective device for electric circuits, the combination of a section of
circuit conductor arranged for bodily removal from the circuit; means normally
subjecting the section of circuit conductor to force tending to thus remove it
from the circuit; and an excess-operated device normally holding the section of
circuit conductor in position to close the circuit, and releasing the same when
operated, so as to allow it to be thrown bodily out of circuit, as set forth.
3-In a protective device for electric circuits, the combination of a circuit-
breaking device adapted to open or break the circuit; means normally subjecting
such device to force which tends to actuate it so as to cause it to break or open
the circuit, but which is held in equilibrium thereby; and an excess-operated
device holding said means normally in engagement with the circuit-breaking
device, and releasing the same when operated so as to permit it to act in a way
to actuate the excess operated device, and thereby break or open the circuit,
substantially as set forth.
4 In a protective device for electric circuits, the combination of a section of
circuit conductor arranged for bodily removal from the circuit; spring means
normally subjecting the section of circuit conductor to force tending to thus
remove it from the circuit, and connected with the same so as to be held in equili-
brium thereby; and an excess-operated device serving as a medium of connection
between the circuit-breaking device and the spring means, and releasing the
latter when operated, so as to permit it to act in a way to throw the section of
circuit conductor bodily out of circuit, substantially as set forth.
.
5 In a protective device, the combination with a base of a circuit-breaking
device, a sliding abutment arranged thereon and capable of striking the base,
spring means exerting force tending to actuate the sliding abutment so as to
cause it to strike the base; and an excess-operated device holding the sliding
abutment against movement on the circuit-breaker.
6-An electrical protective device, comprising a circuit-breaking device for.
automatically opening the circuit; spring means supported upon the circuit-
breaking device and arranged for throwing the latter bodily out of circuit; a
fusible body and a wire section in part embedded in the fusible body and normally
forming a portion of the circuit, said fusible body and wide section being both
arranged upon the circuit-breaking device; and a connection between the fusible
body and the spring when the latter is under tension, substantially as set forth.
7-A protective device, comprising a circuit-breaking device, a plug constructed.
with a hollow conducting member inclosing another conducting member, which
is extended whereby the two members can respectively engage separate contacts;
and means for automatically throwing the plug out of circuit when an unduly .
strong current passes over the line, substantially as set forth.
1
8 In a protective device, the combination with a base having a couple of
metallic sockets, of a circuit-breaking device comprising a couple of metallic
rods adapted to fit into said sockets; a cross-piece connecting said rods; a slide
sliding upon the same; springs tending to force the slide in a direction away from

page_text: the cross-piece; and a heat coil connected with the cross-piece and slide so as to
hold the latter against movement.
9 A lightning arrester comprising opposing blocks of carbon coated with
shellac or like substance.
10-A protector comprising a base having a plurality of pairs of metallic
sockets; circuit-breaking device consisting of metallic rods, cross pieces, springs,
slides and heat coils; and lightning arresters consisting of carbon blocks coated
with shellac or the like.
1
1000
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester and Birmingham.