Improvements relating to Electric Alternating Current Cable Systems
Year: 1898

page_text: Date of Application, 6th June, 1898-Accepted, 17th Sept,
1898
COMPLETE SPECIFICATION.
Improvements relating to Electric Alternating Current Cable
Systems.
I, FRANZ CLOUTI, Rheinische Gummiwaarenfabrik, Cola-Nippes, Germany,
Engineer, do hereby declare the nature of this invention and in what manner the
Bame is to be performed to be particularly described and ascertained in and by
the following statement -
In consequence of the great difference in the phases of the electric tension of
the current and that of the machine chiefly caused by the working of motors and
continuous coils the central station of the alternating current system must in most
cases supply a greater quantity of current than can be usefully employed Now
Owing to then electrostatical capacity the cables hitherto employed produce_a
difference in the phases which 18 directly opposed to that mentioned above
appears therefore easy enough to neutralize the one difference by the other and
thereby to enable a better use to be made of the power of the machine The
resulting difference is equal to zero if the equation stand thus
It
number of periods during which the current is alternating)
current flows quicker than the tension, but if L <
flow as quick as the tension
1
w C
1
If L >
the
wvC
the current does not
If therefore, the capacity is represented in a rectangular system Figure 3 of
co-ordinates as the abscissa and the density of the electric current belonging to
it and required for originating a determined energy a constant tension being
supposed, - 18 represented as the ordinate the points obtained when connected by
straight lines, result in a curve which originate at the axis of the ordinates
approaching that of the abscissa and parting from the latter again when the
capacity increases more and more
1
The distance between the axis of the ordinates and the point representing the
minimum of the density of the electric current 18 in accordance with the equation
wL< and should the system comprise a considerable number of working
rv. C
motors and coils it would be advantageous to increase the capacity between the two
wires serving as direct and as return conductors
•
This is effected by an organisation aimilar to that published in the Specification
of the British Patent No 2394 of 1881 According to such specification the two
conductors are united for the purpose of dispensing with self-induction, in such
a manner that the conductor a being coiled around the conductor b forms therewith
Price 811

page_text: to a certain length a solenoid and, that, in the next following length the con-
ductor 6 18 coiled around the conductor a both again forming a solenoid
This invention makes use of the well known interchanged or cross connection.
thus altering the capacity in order to diminish the difference between the re-
spective phases and also decreasing the danger which arises in handling the con-
nection. By this means I arrive at the result that in a concentric cable system
the inner conductors are connected with the outer ones and the latter again with
the inner conductors
The capacity of both conductors is thus increased by the capacity of the two
condensers (solenoids) arranged one behind the other that is to say, the external
conductor with the earth and the latter with the external conductor
If the cross sections be vaned the scope for altering the capacities and an
accordance with the induction, will be very greatly extended
In those cases in which the above prescribed conditions of limit cannot possibly
be attained, nearly approaching conditions must satisty, as the greater cost of
the cable in case of the varying of the cross sections, also imposes certain limits
Another advantage of my invention is Let A, A, A, A, Figure 1 be the outer
conductors, B, B1, B3, B³ the inner conductors, c, c', c, c³ the capacity between the
inner and outer conductors CCCC the capacity between the outer conductor
and the earth E (lead mantles) T, T', T, To the transformers
Hitherto the conductors of concentric cables have been united in such a manner
that the inner conductor B was soldered to the inner conductor B' and the outer
conductor A to the outer A' (see Figure 1 of the annexed diagrams) In such
case the inner conductors have the full tension of the machine in regard to the
earth
This 18 owing to the fact that the outer conductor in concentric cables
being enclosed in a covering of lead (thus forming a condenser) as in contact with
the earth. The inner conductor however is also in contact with the earth but
through a very small condenser (Lines of dislocation or displacement which may
close a circuit flowing from the bare ends of the inner conductors to the covering
of lead) Therefore there exists another connection between the inner conductor
and the outer one constituted by the current flowing through the two condensers,
from the inner conductor to the earth and from the earth to the outer conductor
Between the two outer terminals of these condensers (the two conductors) the
tension of the machine prevaile As now the tension between the terminals of a
semes of condensers is equal to the total sum of all the angle tensions at the
various condensers the latter being arranged one behind the other are in inverse
proportion to the capacities, it follows that the tension, between the inner con-
ductor and the earth, plus the tension between the outer conductor and the earth,
18 equal to the tension of the machine And further the tensions in the terminals
of the condensors aanged one behind the other are in the inverse proportion to
the capacities
As the capacity of the inner conductor with regard to the earth 16 80 very
small, compared with the capacity of the outer conductor with regard to the earth,
it follows that the tension of the inner conductor with regard to the earth is very
great compared with that of the outer conductor with regard to the earth, o1
in other words, between the inner conductor and the covering of lead the tension
of the machine pievails Now it is possible to dunimsh this tension either by
increasing the capacity of the inner conductor with regard to the earth or by
diminishing that of the outer conductor with regard to the earth, or by doing
both at the same time as is done in the present invention by the interchanging
o cross connecting of the conductors (see diagram. Figure 2) the inner conductor
being connected from length to length with the outer conductor.
The network Figure 2 to be connected up may be composed of various concentric
cables with outer conductors A, A1, A2, A³, and with outer conductors B, B1, B2, B³,
the transformers may be T, T¹, T, T³, the condensors c, c¹, c³, and C, C1, 0°, C³
The cables are connected so that the inner conductor B is connected with the
outer conductor A¹, the outer conductor A' with the inner conductor B³, the inner

page_text: conductor B with the outer conductor A³ and so on. In this case the capacities
of the two conductors are equal to one another therefore also the tensions of
the same with regard to the earth are equal to one half the amount of the tension
in the machine.
It is evident that the system demands less in regard to insulation in this case
as the inner conductors have only to support with regard to the earth one half the
tension hitherto usual This is partacularly important for cables leading to or
connecting houses with the main cable, for sleeves and terminals where generally
the weakest spots in the whole system are to be found and also for transformers
the insulation and securing of which with regard to the earth must be carried out
with the greatest care on account of their connection with secondary systems
But further the increase of tension which was fust observed by Neustadt as occur-
ring when a branch has to be connected with the main system may be obviated
in the improved interchanging or cross connecting system in the same manner
as has been already done in systems of the usual kind (when the inner conductor
is connected with the inner one and the outer conductor with the outer one).
In the improved cross connection the tensions are always smaller in degree
than in the others, other conditions being equal, because of the capacities of the
outer conductors with regard to the earth, being always much stronger
This is
of value especially when, owing to an accident (for instance through the melting
of the keeper of the outer conductor) only the inner conductor of the main cable
is connected with the secondary system.
In conclusion it may be mentioned that the variations of the cross sections
relate only to the capacity, not to the reduction of the tension.
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed I declare that what
I claim is:
The method herein before described of increasing the capacity in an alternatang
current system for the purpose of diminishing the difference in the phases by the
introduction of an interchanging or cross connection arrangement of concentric
alternating current cables, in such a manner that the inner conductor 18 connected
in a certain length with the outer conductor of the adjoining length and the outer
conductor of this second length connected with the inner conductor of the following
length and so on through the whole system, wherein the various series of lengths
may be of different section in the inner and outer conductors in order to obtain
a certain determined value for the capacity.
11
T
1000
H GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said F. Clough