Improvements in Lightning Arresters.
Year: 1891

page_text: Date of Application, 1st Sept., 1891-Accepted, 3rd Oct., 1891
COMPLETE SPECIFICATION.
Improvements in Lightning Arresters.
A communication from abroad by JAMES PERRY FREEMAN, of Washington, in
the District of Columbia, United States of America.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for
Foreign Patent Solicitors 6, Lord Street, Liverpool and 6, Bank Street,
Manchester, both in the County of Lancaster and 323 High Holborn in the
County of Middlesex, 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 :-
This invention relates to improved means for protecting telephones and other
electric instruments and apparatus from the injurious effects of lightning or other
currents of high potential."
The special aims of the invention are to provide a simple and inexpensive device
by which in the event of an abnormal current being received over the line, the
instrument will be automatically cut out of the circuit, the line grounded, the
ground connection maintained during the continuance of the abnormal current, and
thereafter the original connections re-established so that the operative condition of
the system is automatically restored as soon as the danger is passed.
It is also a special aim of the invention to secure the above named results without
introducing into the circuit any additional or variable resistance such as would
interfere with the proper operation of telephones or other sensitive instruments in
stries.
In this instrument a series of independent fusible wires of platinum or similar
material is employed, which are brought one after another into use as a part of the
.ormal or working circuit. These wires are mounted on a rotary or other movable
support, actuated by a spring so that when one wire is burned out, severing con-
nection with the instrument and opening the circuit, the rotation of the support will
bring the next wire into position to re-establish the circuit. With this rotary
carrier are combined ground connections so that after the fusing of one wire has
released the carrier, and before the latter has turned sufficiently to introduce.the
next wire into the circuit, the ground connection will be established.
In the ground line an electro-magnet is located which acts through intermediate
parts to maintain the ground connection and to prevent the introduction of the next
fusible wire into the circuit until the abnormal current has ceased.
In the accompanying drawings are represented those details of construction
which Mr. Freeman recommends as the best embodiment of his invention to
meet the ordinary conditions encountered in practice, but the skilled mechanic
will understand, after reading the Specification, that the invention is susceptible
of embodiment in various forms, the mechanical equivalents of that herein
shown.
In the accompanying drawings
Figure 1 is a perspective view of the device in its normal condition.
Figure 2 is a vertical longitudinal section through the same on the 'line. 2—2,
Figures 1 and 3.
Figure 3 is a transverse section on the line 3-3, Figure 2.
Figure 4 is a diagram illustrating the circuit connections under the normal
condition of the parts.
:
Figure 5 is a similar view showing the connections when the instrument is
grounded.

page_text: Referring to the drawings :—
A represents a base-board giving support to a rigid upright frame, B, of any
suitable form, and C is a rotary barrel supported at its ends in the frame B, by
horizontal pivots, or equivalent supports. D is a spring fixed at one end to the
barrel, and at the opposite end to the base. This spring is kept normally under
tension, and tends to turn the barrel in the direction indicated by the arrow.
The barrel carries at one end an insulating conducting ring e, and at the opposite
end a series of insulated conducting segments alternately arranged. The instru-
ment is connected with the device through the conductor F, joined to a conducting
finger G, which bears constantly upon the ring. This ringe is connected by a
series of fusible wires H, with the respective segments and the wire which is for
the time being uppermost bears against a fixed non-conducting pin or stop, I, which
thus acts through the wire to prevent the rotation of the barrel. A conducting
finger bearing normally on the segments, to which the uppermost or top wire H
is attached, is in turn connected at its opposite end through post K with the line
wire L, from which the current enters the device on its way to the instrument. It
will be seen that in this, the normal condition of the parts, the current, entering
from line L, passes by way of post K, and finger J, to segment, thence through
the top wire H, to ring e, and out by way of finger G and wire F. to the
instrument.
The intermediate segments, which, it will be remembered are insulated from
the segments are connected with each other by conductors', which are in turn
connected to one end of the magnet coil or helix, located centrally in the barrel,
the helix being in turn connected at its opposite end with the ring y, which is in
constant contact with conducting finger M, attached to the ground wire N. These
ground connections have normally no connection with the line. When, however,
an abnormal current fuses the upper wire H, thereby cutting off the connection
with the instrument and releasing the barrel, the barrel is rotated by the spring,
until the finger contacts with one of the segments g, and establishes a ground
connection from the line L, through segment connections with a helix, the
ring, finger M, and conductor N, the main line being thus grounded and the
instrument at the same time wholly disconnected from the line.
In order to maintain the ground connection until the cessation of the abnormal
current a magnetic core of soft iron () is inserted through the helix, and with one
end exposed adjacent to an armature, o, on the lower end of a pin, o', guided on the
main-frame and carrying a stop-arm or pin, o², designed to engage with pins o³ on
the segments g.
When the ground connection is established so that the current is
directed through the helix, the core becoming magnetic attracts the armature and
causes the stop o² to descend in the path of the pins o³, the effect of which is to
arrest the rotation of the barrel in such positions as to maintain the contact of
finger with the grounding segment : in other words to maintain the ground con-
nection. When the abnormal current ceases, the spring of lifts the stop out of
action leaving the barrel free to continue its rotation until the next wire H is
brought into contact with the stop I, and the connected segment brought into
contact with conductor J, the effect of which is to re-establish the original line
connections and sever the ground connections.
It will be observed that the short circuiting of the instrument is accompanied by
the destruction of a single wire H, and that as there are a number of these wires to
be brought into action one after another the device will operate for a long period
of time without care or attention.
The essential features of the structure are a series of fusible conductors to be
introduced one after another into the working circuit combined with a carrier for
Baid wires impelled by a spring or other motor, ground connections established by
the advance of the carrier when released by the fusion of a wire, and a magnet
in the ground circuit to check the movement of the carrier until the current falls
to its normal potential, and it will be obvious that the form and arrangement of the
parts may be variously modified without changing their mode of action.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to he performed, as communicated to me by my
foreign correspondent, I declare that what I claim is :-
1. In combination with the main conductors, a spring-actuated carrier provided
with a series of fusible wires arranged for successive introduction into the circuit
by the movement of the carrier, a stop device co-operating with said wires to
prevent the movement of the carrier, a ground connection opened and closed by the
motion of the carrier, and electro-magnetic stop devices located in the ground line
to arrest the motion of the carrier during the continuance of the abnormal current
to the ground.
2. The rotary barrel provided with the conducting ring e, and the insulated
segments in combination with the fusible wires H, impelling spring D, stop I,
main line conductors G and J, the ground connection M, plate connected to the
segments y, the electro-magnet and the armature and stop device actuated by the
magnet to prevent the rotation of the barrel.
3. In a lightning arrester, the combination of a movable device for opening and
closing the main circuit, a conductor through which the main line is grounded by
the opening of the main circuit, and an electro-magnet in the unbroken ground line
to maintain the ground connection during the continuance of an abnormal current.
4. In a lightning arrester, a spring-actuated device to open and close the main
circuit, said device including fusible connections by which it is held and released, in
combination with a conductor through which the line is grounded when opened, and
electrically-actuated devices in the ground line to maintain its connection and
prevent the re-closing of the main line during the continuance of the abnormal
current.
1 1
LA 1901
WM. P. THOMPSON & Co.,
Agents for the Applicant.