Improvements in Electric Cables and in the Method of Making the same.
Year: 1893

page_text: Date of Application, 27th Dec., 1893-Accepted, 17th Mar., 1894
COMPLETE SPECIFICATION.
Improvements in Electric Cables and in the Method of Making
the same.
I, THOMAS JEFFERSON DEWEES, of Palmyra, in the County of Burlington,
and State of New Jersey, United States of America, Electrician, 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:—
More particularly my invention relates to dry cables in which the insulated wire
or wires are dried at the time of being introduced into or encased in the enclosing
casing, or previously thereto, to expel the moisture and is designed to more
effectively dry the insulated wires and to maintain them in such dry condition. My
improvements are applicable both to the body of the cable or conductor and to the
splices or joints formed therein, and also to the terminal boxes or cases in which
the wires of the cable are connected with the external wires. It is particularly
difficult to maintain a thorough dryness in the splices of the cables and at the
terminal connections, as even the humidity of the atmosphere, the breath, or the
moisture of the hands of the workman when connecting the wires will be sufficient
to affect the insulation resistance of the cable or conductor and thereby reduce its
efficiency. My improved construction enables the cables or wires at the splice or
point of connection to be thoroughly dried and to be maintained in a thoroughly
dry condition after the splice covering or sleeve has been applied and hermetically
sealed.
In carrying out my invention I apply to the cable or conductor, preferably after
it has been dried in the usual manner, a moisture absorbing medium, such as
powdered calcined lime, or an equivalent substance having a strong affinity for
water, which operates to absorb any moisture that may remain in the fibrous
coverings of the wire or wires after they have been dried by the usual methods, or
any moisture that may be communicated to them upon exposure as in the making
of a splice or terminal connection, or through breaks or leaks in the sealed casing
or covering. This lime or equivalent powder quickly absorbs any moisture that
may be present and maintains the cable or conductor insulation in a dry
condition.
To obtain the fullest effect of the lime or equivalent moisture absorbing medium
it should be introduced throughout the spaces between the insulated coverings of
the wires as well as about the cable proper as an entirety.
In the accompanying drawings:
Figure 1 is a longitudinal view of an electric cable having a spliced portion
shown in section and embodying my invention.
Figure 2 is a transverse sectional view on the line of Figure 1 illustrating
my improvements as applied to the body of the cables.
Figure 3 is a plan view of a terminal box with the cover removed illustrating
my invention as applied to the wires therein and
·
Figure 4 is a transverse vertical sectional view of the same on the line y-y of
Figure 3 with the cover attached.
It will be understood that my invention may be applied to a cable or conductor
of any construction and is not limited to application to the particular construction
shown. The cable shown is composed of a series of wires at having an insulated
covering of fibrous material formed into a bunch and enclosed in a fibrous
covering c, the whole being incased in a tightly fitting sheath A of lead or other

page_text: metal. The cable is rendered anhydrous preferably by heating the insulation both
of the single wires and of the bunch or strand of wires and also of the lead
covering while the cable is being constructed.
During the process of forming the dry cable in this or any other suitable
manner, the powdered lime, or equivalent absorptive powder, is applied, being
introduced so as to lie about the cable and as far as convenient within the spaces
between the separate insulated wires which compose it. The powdered lime is
indicated by the reference letter d in the drawings. In practice I prefer to wrap
each wire making up the cable with dry paper or cloth which may be dusted
during the wrapping process with the lime powder, and the series of wires so
wrapped may be gathered into a strand or bunch and tied together by a textile or
fibrous covering such as e which may be formed of braided threads; and if desired
during this latter process in the formation of the cable additional powdered lime
may be applied so as to more or less fill interstices as before set out. All of this
process would take place preferably in a heated and dry atmosphere, and in such
atmosphere the outer metallic sheath or casing may be applied. It is also evident
that the cable proper may be completed if desired and then thoroughly dried and
the lime powder applied before enclosing it in the metal sheath or case.
immaterial to my invention how the cable proper may be formed as my improve-
ments relate more particularly to the method and means of eliminating the last
portions of the moisture. Broadly considered the lime might be applied to a
cable not previously dried and hermetically sealed in the enclosing sheath or
casing.
It is
In the splice shown in Figure 1 the powdered lime is applied in substantially
the same manner. In making the splice the ends of the separate wires are
exposed and united in pairs and the splice coverings Pare applied. The lime or
equivalent powder is sprinkled between the spliced wires and about the cable, and
the splice covering or joint is secured in place and herinetically sealed. The splice
covering B is usually a piece of lead tubing of larger diameter than the lead
tubing forming the sheath or casing of the cable, and its ends are united to the
sheaths or casing of the cable ends by the usual wiped joint customary in plumbing.
If desired the splice may be heated to expel the moisture as far as possible before
the powder is applied. The powder may also be applied within the splice
coverings e which cover the united cuds of the individual wires. In fact it may be
applied in any way so that it is in position to absorb the moisture. In practice the
ends of the cable before the splice is made are necessarily exposed, and, if desired,
to prevent moisture entering, these ends may be sealed with any suitable plastic
substance impervious to moisture. In Figures 3 and 4, my invention is shown
applied to the insulated conductors, wires or cables within the terminal case or
box D. The terminal box or casing may be of any construction, that shown being
selected merely for purposes of illustration. E is the lid or cover of the terminal
box, which may be removed to permit the connection of the conductors a with the
binding posts of contacts in the usual manner. The lime or absorptive powder d
is applied as has been explained and the cover E is attached. The terminal
connections of the wires or conductors may thus be kept dry, and such moisture as
finds its way into the insulated coverings when the connections are being made is
absorbed.
The powder may be applied as well to a single insulated conductor as
to a cable composed of a series of bunched insulated wires. I prefer to use
powdered line as the moisture absorbing medium, as experiment has demonstrated
that it is best suited for the purpose intended, but instead of lime other substances
which have a high absorptive quality, such as magnesia or powdered magnesite,
may be employed. To accomplish the full measure of the invention the powder
must be one having the power of absorbing moisture in a suspended or vaporized
condition and not merely in a liquid form.
By my improvements the insulation resistance of the cable can be made very high
and far above that possible with any other method of insulation.

page_text: Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The herein described method of constructing electric cables which consists in
drying the fibrous insulating covering of the wire or wires to expel the moisture there-
from, applying a moisture absorbing medium, such as powdered lime, to the dried
insulating covering to absorb such moisture as may remain therein, and finally
enclosing the dried fibrous covered wire or wires with the moisture absorbing
medium in a closed sheath or covering.
2. An electric conductor or cable having a fibrous insulation from which the
moisture has been expelled, powdered with a moisture absorbing medium such as
powdered lime, and a closed sheath or covering hermetically sealing the fibrous
insulation in its dried and powdered condition.
3. A splice for an electric cable consisting of the combination of the two cable
ends each composed of one or more insulated wires, and an outer metallic sheath or
casing and in which the ends of the wires of the two cable ends are electrically
united, an insulating covering over the united ends of the wires, a moisture absorbing
substance such as lime applied to the cables at their union, and a splice sleeve or
covering united to the ends of the metallic sheaths of the two cables so as to form
a hermetically sealed splice.
4. An electric cable consisting of an outer closed sheath, a bunch of wires
baving dried insulated coverings within the outer closed sheath, and a powdered
moisture absorbing medium such as powdered lime within the closed outer sheath
and in the spaces between the dried insulated wires.
5. An electric conductor or cable consisting of one or more electric conductors
having a porous insulation, an outer enclosing sheath or case, and a moisture
absorbent material such as lime within the sheath or case and in contact with the
insulation of the wire or wires.
6. An insulated electric conductor having a moisture absorbing material such as
lime applied to its insulating covering.
7. The combination of an electric cable composed of insulated wires, an outer
casing into which the ends of the insulated wires extend, electrical connections with
said wires within the outer casing, and a moisture absorbing material such as lime
applied to said wires at their union with the electrical connections within the
casing.
Dated this 27th day of December 1893.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.