Improvements in Lightning Arresters.
Year: 1897

page_text: Date of Application, 7th Sept., 1897-Accepted, 20th Nov., 1897
COMPLETE SPECIFICATION.
Improvements in Lightning Arresters.
I, CHARLES SCHENCK BRADLEY, of 48 High Street Avon, in the County of
Livingston, and State of New York, United States of America, 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 to that type of lightning arresters which depend for their
effectiveness upon an inductive opposition to a lighning discharge over a path
including translating devices by which the said discharge is caused to take another
path in which no translating devices are included. My invention is especially
applicable to circuits carrying alternating currents, although it may be employed
also with advantage in connection with direct-current circuits.
In carrying out my invention I place the two sides of the circuit in mutual-
inductive relation so that the two inductive effects normally counter-balance each
other, no counter-electromotive force to the flow of the current being offered. This
result may be conveniently effected by enclosing within a transversely laminated
tube two conductors, one carrying the outgoing current and the other the return
current; or by placing two superposed windings on a laminated core, the said
windings being connected respectively to the outgoing and return sides of the
circuit, so as to oppose one another in core magnetization. At the side or sides
of the inductive device I preferably place an ordinary lightning arrester consisting
of two serrated conducting plates separated by a short air gap, and connected in a
branch from the line wires to the earth. As thus organized the dynamo-current
creates no counter-electromotive force, but the lightning discharge by similarly
polarizing both inductive conductors sets up a counter-electro-motive force and
is shunted to earth over the spark-gaps or other points of leakage.
The several features of novelty of the invention will be more particularly herein-
after described and will be definitely indicated in the claims appended to this
specification.
In the accompanying drawings which are hereinafter referred to and which
illustrate the invention, Figure 1 is a diagram of a circuit equipped with my
improved lightning arrestors or protectors. Figure 2 is a sectional view of an
arrester of a modified form of construction.
1, 2 are two main or line wires of a circuit, and 3 a dynamo-electric machine
for supplying current thereto. 4, 4, 4b, are magnetic cores, laminated when
alternating currents are employed. On each core are two coils of wire having the
same number of turns 5, 6, one connected in circuit with one wire 1, and the other
with 2. The two coils are so connected in circuit that they will oppose one another
in a tendency to magnetize the core. 7 and 8 represent electric translating devices,
8 being a motor, which it is desired to protect from damage by lightning. This
may be effected by placing an inductive protector 4", 4b adjacent to the motor, and
by connecting in earth branches from the supply wires ordinary saw-tooth lightning
arresters 9, 10, 9", 10". With this organization the dynamo-currents whether direct

page_text: or alternating will experience no counter-electromotive force, since the two coils
tend to develop opposite poles in the core, and therefore neutralize one another.
The coils should be superimposed on one another or be wound as a duplex conductor
so that there will be no opportunity for the development of consequent magnetic
poles. A simple and effective combination is shown in Figure 2, comprising two
straight conductors insulated from one another and preferably contained one within
the other, the whole being enclosed in a shell of laminated iron. 11, 11 are the
conductors, and 12 the laminated iron shell. Such a device a few feet in length
and placed on the circuit adjacent to the translating device will prove effective
in protecting the same. The device will prove more or less effective without the
iron core or shell, the magnetic circuit being in such a case formed in the air;
iron, however, increases the inductive effect and permits a smaller compass for
the apparatus.
Having particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed I declare that what I
claim is:-
1. A lightning arrester comprising two conductors in mutual inductive relation
having two terminals connected to line and two to a translating device, the said
conductors being associated to oppose one another in magnetizing effect under
the working current passing to the translating device, thereby permitting such
current to pass freely, but assisting one another in magnetizing effect when the line
is charged by a lightning stroke, substantially as hereinbefore described and as
illustrated by the accompanying drawings.
2. A lightning arrester comprising two conductors in mutual inductive relation
having two terminals connected to line and two to a translating device, the said
conductors being associated to oppose one another in magnetizing effect under
the working current passing to the translating device, thereby permitting such
current to pass freely, but assisting one another in magnetizing effect when the
line is charged by a lightning-stroke, and a ground connection of high resistance
but low impedance at or near the lightning arrester, substantially as hereinbefore
described and as illustrated by the accompanying drawings.
3. The combination with a pair of lines connected to one or more translating
devices, of an interposed lightning arrester comprising two conductors surrounded
by a magnetic core and connected with the lines to neutralize one another in
magnetizing effect under current traversing them in opposition, but impeding
the passage of lightning discharges entering from the lines, substantially as herin-
before described and as illustrated by the accompanying drawings.
4. A lightning arrester constructed and arranged substantially as hereinbefore
described and as illustrated by the accompanying drawings.
Dand this 9-1 1
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