Improvements in Earthed Coverings or Electrical Tubular Conductors.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Earthed Coverings or Electrical Tubular Conductors.
I, JAMES YATE JOHNSON, of 47, Lincoln's Inn Fields, in the County of London,
Gentleman, do hereby declare the nature of this invention (which has been
communicated to me from abroad by the Firm of Hartmann & Braun, of Bocken-
heim, Frankfort-on-Maine, in the German Empire) to be as follows:-
In the employment of electric currents of high tension for electric lighting
and for electric transmission of power it is necessary that the conductors should
be protected from any direct contact by a system of earthed coverings which
should be of such dimensions, that any excess of current occurring in the system,
can be passed to earth. As the coverings must be so constructed as to admit
of conveying currents of great strength they can also be employed directly as
earthed electric conductors.
The most reliable laying is obtained by embedding the conductors in a well
earthed system of metal tubes.
In a continuous-current three-wire system with earthed central conductor the
metal tube system as a bare central conductor may be employed, but is to be
carried through up to the lamp itself. The outer conductors in this case are
each situated in a separate metal pipe, so that any mutual direct contact with
the external conductors is prevented.
As the system of metal tubes serves for conduction, the tubular device must
be such, as to be capable on the one hand of conveying the current, and, on
the other hand, it must have sufficient mechanical resistance for protecting: the
conductors inserted therein.
Insulating pipes with a thin metallic coating are entirely out of the question.
Insulating pipes with strong metallic coating could be used, but they have
the disadvantage, that the insulation has to be interrupted at every joint,
therefore becoming entirely worthless as an insulation, and that the good
electrical connection of the joints offers great difficulties.
The main difficulties heretofore encountered in the general application of a
metal tubular system of this kind, are the following:
The tubular system must be of a good electric conducting capacity throughout
its length and be capable of conveying the whole current: the joints of the
tubes must be well connected electrically, the tubes must not be too heavy and
the mounting must be easy and simple.
The object of this invention is to provide means which fulfil these conditions
and overcome the foregoing difficulties. According to this invention tubes are
employed which are formed from a strip of metal bent in such a manner that a
longitudinal groove is formed, the edges of the metal not coming into contact,
so that between them a small air space is left. The tubes so constructed are
very elastic in the transverse direction.
In order to make the connection, the metal at the ends of adjacent tubes is
pressed together and the said ends are received in a sleeve or the like and on

page_text: the tube ends being released from pressure, they spring out again and firmly
apply themselves against the inside of the sleeve or the like. In order to over-
come small irregularities and roughnesses of the parts in contact, a cap or cover
of tin foil or other soft metal is inserted between the tube and the sleeve so
that good contact between the tube and the sleeve is insured.
The sleeve is provided with an internal projection to form a stop for the tubes
inserted from each end. Inspection holes permit of inspecting the device.
For obtaining connections which can be separated (analogous to the long-thread
connections or couplings in gas and steam conduits) sleeves without internal
projections or heads are employed, the sleeve, in that case, being first slid
wholly over the one tube, and subsequently slid back partly onto the other tube
brought against it. If the tubes are required to be water-tight; the joint is
filled up with a suitable material, or a trough-shaped spring metal strip can be
inserted so as to wedge itself between the edges of the tube, the said strip
yielding to the elastic force of the tube and yet securely closing the longi-
tudinal groove therein.
.
By the employment of the aforesaid transversely elastic tubes in connection
with rigid sleeves a tubular device is produced with joints having good electrical
connection. The tubes may, of course, be made rigid and the sleeves elastic.
As no screw threads are required in the construction of the tubular device,
the thickness of the walls of the tubes may be so small as to just suit the
mechanical resistance required but if the walls of the tubes are thin, the con-
ducting capacity of the system of tubes naturally becomes smaller in proportion
and to overcome this objection, in addition to the tubular device a copper or
other metal wire is laid, this wire being electrically well connected at least once
to every individual piece of the tubular system.
By this means the tubular device becomes suitable for conveying the current
without employing walls of large thickness, or using copper tubes, and any
danger from bad joints is obviated. Even if a joint were not to form any con-
tact whatever, so that the tubular device would be completely without current
behind the joint or, that, in the case of an earthed tubular protecting device,
for high tension currents the earthing were completely interrupted, every dis-
turbance or danger resulting therefrom is completely obviated.
The connection of the secondary conductor with the tubular system may, of
course, be executed in various ways, by screws, clamps or the like, as well as
by using the tubes themselves for jamming the secondary conduit into secure
position, or by arranging the aforesaid closing strip to serve as a secondary
conductor.
COMPLETE SPECIFICATION.
Improvements in Earthed Coverings or Electrical Tubular Conductors.
I, JAMES YATE JOHNSON, of 47, Lincoln's Inn Fields, in the County of London,
Gentleman, do hereby declare the nature of this invention (which has been
communicated to me from abroad by Hartmann & Braun, of Bockenheim,
Frankfort-on-Maine, in the German Empire) and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement:-
i
In the employment of electric currents of high tensión for electric lighting

page_text: and for electric transmission of power it is necessary that the conductors should
be protected from any direct contact by a system of earthed coverings which
should be of such dimensions, that any excess of current occurring in the system,
can be passed to earth. As the coverings must be so constructed as to admit
of conveying currents of great strength they can also be employed directly as
earthed electric conductors.
The most reliable laying is obtained by embedding the conductors in a well
earthed system of metal tubes.
In a continuous-current three-wire system with earthed central conductor the
metal tube system as a bare central conductor may be employed, but it is to be
carried through up to the lamp itself. The outer conductors in this case are
each situated in a separate metal pipe, so that any mutual direct contact with
the external conductors is prevented.
As the system of metal tubes serves for conduction, the tubular device must
be such, as to be capable on the one hand of conveying the current, and on
the other hand it must have sufficient mechanical resistance for protecting the
conductors inserted therein.
Insulating pipes with a thin metallic coating are entirely out of the question.
Insulating pipes with strong metallic coating could be used, but they have
the disadvantage that the insulation has to be interrupted at every joint
therefore becoming entirely worthless as an insulation, and that the good
electrical connection of the joints offers great difficulties..
The main difficulties heretofore encountered in the general application of a
metal tubular system of this kind are the following:
The tubular system must be of a good electric conducting capacity throughout
its length and be capable of conveying the whole current; the joints of the
tubes must be well connected electrically, the tubes must not be too heavy and
the mounting must be easy and simple.
The object of this invention is to provide means which fulfil these conditions
and overcome the foregoing difficulties. According to this invention tubes are
employed which are formed from a strip of metal bent in such a manner that a
longitudinal groove is formed as shewn in side view and cross section in Figure 1
of the accompanying drawings edges R R2 of the metal not coming into con-
tact, so that between them a small air space L is left. The tubes so constructed
are very elastic in the transverse direction.
In order to make the connection, the metal at the ends of adjacent tubes is
pressed together and the said ends are received in a sleeve. or the like M (see
Figure 3) and on the tube ends being released from pressure they spring out
again and firmly apply themselves against the inside of the sleeve or the like.
In order to overcome small irregularities and roughnesses of the parts in contact,
a cap or cover of tin foil or other soft metal K Figure 2 is inserted between
the tube A and the sleeve M (see Figure 3) so that good contact between the
tube and the sleeve is insured.
The sleeve is provided with an internal projection B to form a stop for the
tubes inserted from each end. Inspection holes c¹² permit of inspecting the
device. For obtaining connections which can be separated (analogous to the
long-thread connections or couplings in gas and steam conduits) sleeves with-
out internal projections or heads B are employed, the sleeve in that case being
first slid wholly over the one tube and subsequently slid back partly onto the
other tube brought against it. If the tubes are required to be watertight, the
joint is filled up with a suitable material or a trough shaped spring metal
strip D (Figure 4) can be inserted so as to wedge itself between the edges
R. R2 of the tube A the said strip yielding to the elastic force of the tube A.
and yet securely closing the longitudinal groove therein.
By the employment of the aforesaid transversely elastic tubes in connection
with rigid sleeves a tubular device is produced with joints having good electrical
connection. The tubes may of course be made rigid and the sleeves elastic.

page_text: As no screw threads are required in the construction of the tubular device,
the thickness of the walls of the tubes may be so small as to just suit the
mechanical resistance required but if the walls of the tubes are thin, the con-
ducting capacity of the system of tubes naturally becomes smaller in proportion
and to overcome this objection in addition to the tubular device a copper or
other metal wire is laid, this wire being electrically well connected at least once
to every individual piece of the tubular system.
1
F...
171
By this means the tubular device becomes suitable for conveying the current
without employing walls of large thickness, or using copper tubes, and any
danger from bad joints is obviated. Even if a joint were not to form any con-
tact whatever, so that the tubular device would be completely without current
behind the joint or that in the case of an earthed tubular protecting device,
for high tension currents the earthing were completely interrupted every dis-
turbance or danger resulting therefrom is completely obviated.
The connection of the secondary conductor with the tubular system may of
course be executed in various ways by screws, clamps or the like as well as
by using the tubes themselves for jamming the secondary conduit into secure
position, or by arranging the aforesaid closing strip D to serve as a secondary
conductor.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1. In electric tubular conductors or earthed coverings slotted metal tubes
elastic transversely, in combination with non-elastic sleeves or elastic sleeves
in combination with non-elastic tubes substantially as herein before described.
2. In combination with transversely elastic tubes of the kind referred to in
the foregoing claim a transversely elastic metal strip (such as ID)) inserted. in
the longitudinal slot. of the tube for the purpose of closing it as hereinbefore
explained.
3. In combination with a tubular conducting device of the kind referred to
in the first claim of a cap or cover of soft metal between the tube and the sleeve
for ensuring good electric contact as herein before explained.
4. In a tubular conducting device of the kind referred to in the first claini,
a wire connected in parallel and attached electrically to each individual piece of
the tubular conductor for the purposes hereinbefore referred to.
Dated this 12th day of March 1900.
37
h-
r.
JOHNSONS & WILLCOX.
47, Lincoln's Inn Fields, London, WC, Agents.