Improved Means for the Distribution of Electricity.
Year: 1890

page_text: Date of Application, 22nd Aug., 1890
Complete Specification Left, 22nd May, 1891-Accepted, 27th June, 1891
PROVISIONAL SPECIFICATION.
Improved Means for the Distribution of Electricity.
We MICHAEL VON DOLIVO-DOBROWOLSKY Engineer and PAUL MAMROTH
Director of the Company "Allgemeine Elektricitas Gesellschaft" trading under
the name of this Company both residing at No. 26 Schlegelstrasse Berlin Kingdom
of Prussia German Empire do hereby declare the nature of this invention to be as
follows:-
This invention relates to the distribution of electric alternate currents of different.
phases that is to say alternate currents produced by machines whose armatures are
provided with coils differently situated relatively to the magnetic poles and wherein
the coils that are situated symmetrically relatively to the magnetic poles are con-
nected in groups. The alternate currents produced by machines of this description
are as is well known especially necessary for working that class of electro motors
which are based upon a principle established by Professor Ferrari.
The invention has for its object to effect the distribution of alternate currents of
the above mentioned description to a number of circuits with the aid of only one
neutral conductor or compensating conductor for all the said circuits. With this
object the invention consists in so connecting the coils with one another that the
resulting electro motive forces are actually connected in series and then connecting
together the n groups of coils of the armature at one of their ends at a common
point and connecting a conductor at this point the other end of each group of coils
being connected with the main conductors. Between each two of the latter equal
mean electro motive force exists the corresponding groups of coils being perfectly
symmetrically situated and this electro motive force is halved or nearly so at the
above mentioned connecting point. The conductor connected at this point can
thus be utilized as a neutral.conductor for each pair of main conductors. A system
ofn I conductors is thus obtained which represents a concentration of systems
of 3 conductors each of which is traversed by currents of equal distance of
phase.
The lamps are connected according to their resistance either between the com-
pensating conductor and the main conductor or between two main conductors.
The electro motors in so far as they employ currents of different phases have the
coils connected in analogous manner to the generator coils and are preferably
arranged in branch circuits from all the n + 1 conductors. The transformers in so
far as they employ currents of different phases likewise have n groups of coils
which are connected at one end with one another and with the compensating
conductor the other end of each group being connected with the main conductor.
In order to regulate the difference of potential between the individual main
conductors and the neutral or compensating conductor either automatically or by
hand regulating apparatus such as induction coils or the like are so connected with
the system their n coils are connected at one end with one another and with the
neutral conductor the remainder of the coils on the other hand being adjustably
connected with the main conductors.
The advantages of the new system are as follows:-Possibility of leading off
currents of different electric motive force; equalization of the current by the
neutral conductor when the individual sections of the system present different
degrees of resistance; facility for compensating for falls of electro motive force and
economy in conducting materials only one compensating conductor being required
which may be of smaller section than the conductor.
Dated this 22nd dox of August 1900
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, Agents.

page_text: COMPLETE SPECIFICATION.
Improved Means for the Distribution of Electricity.
We MICHAEL VON DOLIVO-DOBROWOLSKY, Engineer and PAUL MAMROTH
Director of the Company "Allgemeine Elektricitätsgesellschaft" trading under
the name of this Company both residing now at 22 Schiffbauerdamm Berlin in the
Kingdom of Prussia, German Empire, do hereby declare the nature of this inven-
tion 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 the distribution of alternating currents of electricity of
various or different phases, that is to say, alternating currents which are produced
by machines in which the armature is provided with coils differently arranged in
relation to the magnetic poles, the coils arranged symmetrically to the magnetic
poles being combined or connected in groups. The alternating currents produced
by machines of this kind are, as is well known, especially necessary for driving
electric motors based on the principle established by Professor Ferraris.
More particularly the invention concerns the system of distribution of currents
of the aforesaid kind in which a neutral or compensating wire or connection is
employed, as in the three-wire system, and relates to the combination with the
different external conductors of induction coils transformers or other regulating
devices as hereinafter described whereby the difference of potential between the
external conductors and the neutral wire is enabled to be regulated automatically
or by hand, the coils of the said regulating devices being so connected with the
mains and with the neutral wire or connection that an independent regulation of
the different branches when unequally charged is rendered possible such regulation
being attainable with difficulty or not at all without the said neutral wire or
connection.
And in order that our said invention may be fully understood we shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures on the annexed sheets of drawings the same letters of reference
indicating corresponding parts in all the figures.
In the distribution of electricity from a central station to great distances what is
known as the three wire system is largely employed chiefly on account of the
economy which it effects in the conducting materials. When this system is
employed it is of importance when the lamps or consuming devices are equally
distributed on both halves of the system that the middle or central conductor
should be without current and this conductor is thereby enabled to be made very
thin whilst the current in the two outside conductors is required to be only half as
strong as it would have to be if two conductors only were employed to supply the
same number of consuming devices or apparatus.
For working with a constant current the electricity is generated by means of two
dynamos arranged in series, or a battery of accumulators the compensating or
neutral conductor being connected at a point in the middle of the battery or
between the two dynamos. When working with ordinary alternate currents on the
other hand only one generating dynamo is required. The extremities of the
armature coils are connected with the two outer conductors and the middle or
central part of the said coils with the neutral conductor and it is clear that in this
case also the middle conductor may carry no current. In both cases heretofore
considered it is of importance that both halves or divisions of the three wire system
even when working together should be completely independent of each and that the
tension in either division should be capable of being regulated without interfering
with the other division.
The dynamos recently constructed with a number of groups of coils differently
arranged in relation to the magnetic poles (such as the machines designed by
Heisler, Tesla and others) differ greatly from ordinary alternate current machines,
they utilise the materials more advantageously than do machines with a single

page_text: system of coils and on the other hand they supply alternating currents of different
phases such as are required for working motors constructed according to the
Ferraris system. The individual circuits of these machines may, as represented in
Figure 1 of the accompanying diagrams, representing the case of two currents
generated in coils 1, 11, 2, 21, shifted to an angle of 90 degrees to one another and
supplying two main wires A and B have one central conductor C in common as
described in the Specification accompanying Schallenberger's application for
Letters Patent in the United States of America No. 412,932 but even when the
resistances in the two divisions are equal this central wire is never without a
current as is the case with the neutral or compensating conductor of the three wire
system. It must on the other hand be calculated for receiving the whole of the
An
current and consequently admits of no economy in the conducting material.
arrangement combining all the advantages of the three conductor system is possible
with currents of different phase only when the interval between the phases of the
individual currents is equal to the full period that is to say 2π divided by the
number of these currents as is the case with a dynamo whose individual coils or
groups of coils are equally distributed over the core of the armature. Take for
example the case of an armature with only 3 groups of coils which consequently
furnish 3 currents of a difference of phase corresponding to 120 degrees. Under
these conditions the strengths of the currents circulating in the coils of the dynamo
in a given moment if the three circuits are equally loaded, are represented by-
The algebraical sum of these currents is equal to zero at every moment or what
amounts to the same thing each individual current is equal to the sum of the two
others (irrespective of the sign). This circumstance renders it possible to allow all
the three currents. to converge or-meet at one point as represented at m¹ in the
diagram Figure 2.
The main conductors for these three currents are represented by the lines A B C.
The corresponding coils being symmetrically arranged the same mean tension
exists between each two of such conductors (provided that the coils are equal) and
the tension between two of these external conductors is halved at the point m'. A
conductor N connecting the point m¹ with the point m may now be employed as the
neutral conductor for each two conductors A B C that is to say any two of the
conductors A B C constitute in combination with the conductor N a separate
three wire system. This arrangement taken as a whole constitutes a combination
composed of three three wire systems supplying alternating currents of a difference
of phase corresponding to 120 degrees.
The arrangement described presents the same advantages as does the ordinary
three wire system in the case of continuous currents. Two different tensions are
available in the distribution system which can be employed in accordance with the
nature of the consuming devices. The conductor N which carries no current when
the consuming devices are equally distributed on the individual branches further
receives the excess current when the charges are unequal precisely in the same way
as in the ordinary three wire system.
According to this invention this arrangement of the neutral conductor enables
each one of a combination of complex interlocking or overlapping alternate currents
to be separately regulated without influencing the others as hereinafter described.
Without the employment of the neutral conductor the transmission to a distance of
electrical energy is indeed possible (see Specification annexed to Letters Patent
No. 1955580) but in this case the currents in the individual conductors are not
independent of one another.

page_text: This will be readily understood on referring to Figure 3 which represents an
arrangement of circuits A B C supplying lamps for example at D¹ D² D³ of which
one conductor marked B carries no current whatever (the lamps at D² being cut
out) whilst two others A and C are very unequally charged (the number of lamps
in circuit at D¹ and D³ being unequal) thus shewing the inter dependence of the
currents in the three conductors A B C for in the said case the two groups of lamps
between the conductors A and C are connected in series and no regulation of one
group is possible without interfering with the other group.
Every attempt at regulating the current in one of these conductors affects the
other two and leads to a modification in the distribution of the current which
cannot be foreseen so that with considerable fluctuations in the charge requiring
frequent readjustment it is almost impossible in practice to employ an arrangement
such as that represented in Figure 3.
The conditions are different however when as represented in Figure 4 a neutral
conductor N is combined with the pairs of main conductors A. B. C. and the
electrical consuming devices at D' D2 D3 are put in circuit between the neutral and
the main conductors. In this case regulating apparatus of any suitable form such
as the regulating resistances employed with continuous currents or preferably
regulating induction coils may be placed in the outer conductors as represented
at R₁ R, R3.
By means of this arrangement the tension in each branch between the outer or
main conductors and the neutral conductor N is enabled to be independently modified
to any required extent without influencing the other circuits. Other electrical
consuming devices requiring currents of higher tension may if desired be put in
circuit between the main conductors A B C but these are not subject to the same
advantageous conditions as the tension or charge between any two main conductors
cannot be independently regulated.
A more advantageous arrangement consists in combining the regulating device
for all the three divisions or branches in one apparatus as represented in the diagram
Figure 5.
S, S2 S3 represent regulating coils wound upon the limbs or radial arms of an
iron ring or wheel E being connected at m with one another and with a compen-
. sating conductor N. The main conductors A B C are immoveably attached to the
coils S₁ S₂ S, at a b and c and the regulating or controlling mechanism acts upon
moveable contacts x y z connected with the conductors and which are capable of
sliding over the turns or windings of the coils S₁ S, S₁. It is evident that by
displacing the sliding contacts a yz any desired modification in the tension can be
obtained and the electrical consuming devices can be caused to receive any desired
pressure equal to or greater or less than the pressure in the machine according to
the position of the moveable contacts x y z. This arrangement is especially useful
in compensating for the drop in the pressure which is unavoidable in transmitting
currents to considerable distances.
When the transmission of the electrical energy to a distance takes place with a
considerable increase of pressure a transformer may be employed with advantage
as a regulator. In this case an arrangement such as that represented in Figure 6
is employed. Three long or main conductors a b and c are connected with the
secondary coils S¹, S₁₂ S¹ of a transformer the primary coils S, S, S, being provided
with moveable or sliding contacts P, P, P, to which the current of lower pressure
or tension is supplied by or through the conductors A. B. C. The ends
3
2
3
of
the wires of the secondary coils S1, S2 S¹, are connected with a neutral or com-
pensating wire n at m' as indicated by the dotted lines s₁₂, in like manner to the
wires of the primary coils, the main conductors a b c being connected to the other
or free ends of the said secondary coils. It is evident that in the arrangement
firstly hereinbefore described the long or main conductors may be fixedly connected
at a point on the coils the ends of the conductors proceeding from the machine being
connected to sliding contacts.
The diagram Figure 7 represents an arrangement in which the simple transformer

page_text: hereinbefore described with reference to Figure 6 is replaced by three separate
transformers T₁ T, T, having adjustable contacts P₁ P2 P3 in connection with the
secondary coils. This arrangement will be readily understood without further
description by referring to the diagram Figure 7.
In the foregoing description of the invention arrangements are described designed
for systems in which 3 alternating currents of a difference of phase corresponding
to 120 degrees but it is evident that the invention is equally applicable to
systems comprising more currents with a correspondingly smaller angle of interval
between the phases. The number of currents has no influence on the possibility of
regulating each current individually.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what
we claim is :-
:-
1. In an electrical distribution system presenting the following characteristics
namely; (a) alternating current generators with n groups of coils on the armature
differently situated relatively to the magnet poles all of the said coils being
connected together at one end and provided with n + 1 connections for the supply
of current; (b) n + conductors one of which being a neutral or compensating
conductor is united with the connecting point of every n coils the others being
connected with the free ends of the coils; and (c) electrical consuming devices such
as lamps etcetera which are put in circuit between one of the outer or main conductors
and the neutral conductor; the introduction in the outer or main conductors of
regulating devices such as resistances or induction coils controlled automatically or
by hand for the purpose of regulating the pressure at the consuming devices in the
individual branches without influencing the others substantially as hereinbefore
described with reference to the accompanying diagrams.
2. In electric distribution systems of the class referred to in the preceding
claiming clause the uniting of the regulating apparatus of all the outer conductors
in one single apparatus the several coils of the latter being connected at one of their
extremities with one another and with the neutral conductor, the other extremities
(or parts of the coils) being separately connected with the main conductor
substantially as hereinbefore described with reference to Figure 5 of the accom-
panying diagrams.
3. In electric distribution systems of the class referred to in the first claiming
clause the uniting of the regulating apparatus with a transformer for the purpose
of regulating the pressure in long distance conductors by changing the number of
turns of wire in the primary or secondary coils of the transformer substantially as
hereinbefore described with reference to Figure 6 of the accompanying diagrams.
4. In electric distribution systems of the class referred to in the first claiming
clause the substitution in the place of the multiple phase transformer referred to in
the preceding claiming clause of a series of single transformers by means of which
the tension between the outer or main conductors and the neutral conductor is
enabled to be augmented in an independent and adjustable manner substantially as
hereinbefore described with reference to Figure 7 of the accompanying diagrams.
Dated this 22nd day of May 1891.