Improved Continuous Electric Current Distributing System.
Year: 1893

page_text: Date of Application, 16th Oct., 1893-Accepted, 18th Nov., 1893
COMPLETE SPECIFICATION.
Improved Continuous Electric Current Distributing System.
We MICHAEL VON DOLIVO-DOBROWOLSKY of No. 22 Schiffbauerdamm at
Berlin in the Kingdom of Prussia, German Empire, Engineer, and the Company
"ALLGEMEINE ELEKTRICITÄTS-GESELLSCHAFT" of the same place 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 the distribution of continuous electric current and more
especially to the feeding with such current of two series connected consumption
circuits by the aid of the so called three wire system, and its object is to enable
this system to be worked by the medium of but one current generating machine
without sparking being caused at the point of connection between the neutral or
compensating wire and the dynamo machine.
It is a well known fact that electric current distributing systems can be carried
out with great saving of conducting material by employing high tension currents.
Where the consuming apparatus are bound to a predeterminate maximum tension,
the tension of the system can be caused to redouble or to treble or to increase to a
still higher degree by uniting some of the consuming apparatus into groups and
connecting the latter in series. Now the ordinary mode of establishing series
connection of groups of consuming apparatus is very defective in rendering the
groups dependent on each other. To prevent this use is frequently made of
Hopkinson's so called "three conductor system." In this system there are two
series connected groups of consuming apparatus, two series connected generating
machines, two main conductors for connecting the former with the latter and a
third conductor, called "neutral" or compensating" conductor, which is branched
off from the point of connection of the two generating machines and connects in
series the two current consuming groups. The principal disadvantage of the so
combined system resides in the absolute necessity of providing for at least two
generating machines. The attempts hitherto made to enable this three conductor
system to be worked by the aid of but one current generating machine have been
without any practical result from the reason of the sparking caused on the com-
mutator by the third brush. required to connect the compensating conductor with
the generating dynamo.
Now we have discovered that the feeding of two series connected consumption
circuits of like tension with continuous current from but one generating machine
can be arrived at without the collector of the latter being subject to sparking by
properly applying the following principle: Dividing the exceeding current flowing
back through the compensating wire into two partial currents and causing the
latter to directly flow at diametrical opposite points into the armature winding of a
dynamo connected with the mains, the said dynamo consisting either in the
generating dynamo itself or in a compensating machine, viz. a dynamo, receiving
current from the mains and running as an electro motor. Based on this principle
the present invention consists in connecting the compensating conductor with the
armature winding whether of the generating dynamo or a compensating dynamo by
the medium of a self induction coil in such a manner that the centre of the latter is
connected with the compensating conductor, whilst by its ends it is connected with
the armature winding at diametrically opposite points. Moreover, the said coil is
given such a high self induction as is necessary to prevent it from being traversed
by alternating current impulsions whilst the resistance opposed by it to the passage

page_text: of a continuous current is but insignificant. By virtue of this organisation on the
one hand the alternating current impulsions generated in the armature winding are
prevented from passing over into the compensating conductor by way of the
induction coil, whilst on the other hand the continuous current flowing back through
the said conductor is permitted to pass into the armature winding by the way of
the induction coil without resistance, so that the feeding of the two series connected
circuits continues without the tension of the latter being altered.
The said self induction coil may be so arranged as to rotate with the armature of
the generating machine or so as to be stationary, each end forming a brush that is
is caused to slide on a ring-shaped conductor fixed on the armature shaft and
electrically connected with one of two diametrically opposed points of the armature
winding.
And in order that the present invention may be fully understood we proceed to
describe the same in a more detailed manner reference being made to the annexed
drawings forming part of this Specification.
Fig. 1 is a diagram of the improved three conductor system with the self induc-
tion coil rotating with the armature of the current generating machine, the latter
being supposed to be a bipolar dynamo.
Fig. 2 is a diagram of the improved three conductor system with the induction
coil being stationary, the generating bipolar dynamo being represented in side
elevation in order to show the arrangement of the brushes and contact rings
establishing permanent electrical connection between diametrically opposed points of
the armature winding and the ends of the self induction coil.
Fig. 3 is a diagram of a form of the improved system in which the compensating
conductor is connected through the self induction coil with the armature winding
of a compensating machine, the self induction coil being stationary and connected
with the armature winding in the same way as in Fig. 2.
Referring to Fig. 1 a denotes the ring shaped armature of the bipolar generating
dynamo A, a¹ the armature winding, N and S respectively the north and south
poles of the field magnet, and 6', 62 the brushes feeding the mains m² and m². To
simplify the drawing the commutator has been omitted, and the brushes are supposed
to slide directly on the armature winding a¹. i is the self induction coil.
The coil i is arranged within the armature, and, moreover, it is attached to the
armature shaft so as to rotate with the same. The ends and of coil i are
respectively in electrical connection with diametrically opposed points of armature
winding a¹, as for instance with the points a² and a³. m the neutral or com-
pensating conductor connecting in series the two consuming circuits lettered vl
and and containing for instance lamps respectively 11 and 12. This neutral
conductor is electrically connected with the centre of self induction coil i.
When the armature a is caused to rotate, an alternating tension takes place at
the points of connection a² and a³, but, as the construction of coil i is such as to
give rise to a high degree of self induction, this coil will not permit any appreciable
quantity of alternating currents to flow through it. The centre 3 of coil has the
mean potential relatively to all the points of the armature winding a¹; from this
it results not only that the difference of tension between ¹ and is equal to that
between 2 and 3, but that likewise the difference of tension from brush b² towards
the point is equal to that from brush 62 towards the said point.
As known the connecting coil i can be made with a very high degree of self
induction by coiling it on a closed body of iron e.
As long as the number of working lamps respectively 11 and 12 is alike on
each of the circuits v¹ and v³, the tension in the circuit is equal to that in
the circuit and there exists no current in the conductor m³ as it is in the middle
between the two tensions. But as soon as there are more lamps working in one
circuit than in the other, the consumption of current is greater in the former
than in the latter, and the exceeding current will flow through the compensating
conductor m³ in the direction of the arrow, i.e. towards the centre of the

page_text: connecting coil i. Arrived at this point the current splits up into two partial
currents, one of which passes towards and through the point a² in the armature
winding a', whilst the other passes towards and through the point a³. As the
returning current is a continuous current, the passage of the two partial currents
resulting from its splitting up in the point 3, will not be resisted in any appreciable
degree by the coil i. Thus the tension of the two series connected groups of
consuming apparatus is maintained at the same degree; whether there is a greater
consumption of current in the one or the other group, the exceeding current is
always allowed to flow back immediately into the armature of the generating
machine through the conductor m³, and the coil i.
It is by this means that the two series connected groups of consuming apparatus
are rendered perfectly independent on each other notwithstanding there is but one
generating machine for feeding them with current.
In many cases it will not be possible nor will it be advantageous in all instances
to place the connecting self induction coil within in the armature, and so as to
rotate with the same, so that the said coil must be disposed out of the generating
machine. In such cases the coil is preferably arranged stationary and provision is
made for causing uninterrupted connection of its ends with diametrically opposed
points of the rotating armature. Such an arrangement is diagramatically
represented in Fig. 2.
As in Fig. 1 N and S denote respectively the north and south poles of the field
magnet of a bipolar generating dynamo A, a the ring-shaped armature of same
being fixed on the shafts s, c the commutator to which the mains m' and m² are
connected through the medium of the brushes b and 62, i the self induction coil
for establishing electrical connection between the compensating conductor m³ and
two diametrically opposed points of the armature, and e the closed body of iron
placed within coil i. On the shafts are fixed two ring shaped contacts, 18 and 1º,
which are insulated from each other. These rings are connected by means of two
wires and, with diametrically opposed points of the armature. The end ¹ of
the selfinduction coil i is connected by a wire i to a brush, that rests permanently
on contact ring, and the other end, 2, of coil i is connected by a wire, ³, with a
brush 7, which is permanently resting on contact ring 9. Thus, when the armature
is caused to rotate, the contact rings 18 and are forced to rotate with it, and in
doing so they rub against the brushes and 7, whereby the permanency of electrical
connection between the ends of coil and the said two opposed points of the
armature winding is maintained, and consequently the free return of the exceeding
current to the same allowed to take place at all times.
Fig. 3 illustrates diagramatically a three conductor system in which the two
series connected groups of consuming apparatus are fed with current by one
common generating machine and in which the connecting self induction coil i is made
use of in combination with a so called compensating machine, i.e. a dynamo
running as a motor and serving for taking up the exceeding current.
A denotes the generating bipolar dynamo having the brushes b¹ and 6ª to which
are connected the mains m² and m². and 2 are the two consuming circuits to be
fed with current at like tension from the dynamo A, and m³ is the compensating
conductor by which the circuits and 2 are connected in series. In proximity
of the latter is arranged a bipolar dynamo A with ringshaped armature a*, the
coil a** of which is connected with the mains through the collector cx, the brushes b*
and 6xx, and the conductors m* and m**. s* is the shaft carrying the armature a*
and the collector e*. i denotes the self induction coil to the centre of which is
connected the compensating conductor m³. In this case the coil is not brought
into relation with the armature winding of the generating dynamo A, but with the
armature winding a** of the compensating machine A, the arrangement being
supposed to be made as described with reference to Fig. 2. That is to say: the
coil i provided with the closed iron body e is arranged out of the armature and
stationary, and its ends, 2 and 3, are connected by wires and is, with brushes,

page_text: and, rubbing against ringshaped contact pieces, and 1, fixed on the armature
shaft and connected by wires, and ", and the collector c* with diametrically
opposed points, a² and a³, of the armature winding a**.
When the system is working the dynamo A× is fed with current from the mains m¹
and m² through the conductors m* and m**, whereby it is caused to rotate, the high
self induction coil i preventing the current from passing through this coil. As long
as there is a like number of consuming apparatus working on the circuits v¹ and v²,
there will also be a like tension in both of them, consequently the middle con-
ductor m³ will receive no current and the dynamo A will work at the same rate.
But as soon as the number of working apparatus is changed in one or the other
consuming circuit v¹ or v², the excess of current will be led through the conductor m³
(see direction of arrow) towards the centre ³ of coil i, where it splits up into two
partial currents passing into the armature winding a** as described with reference
to the coil a' of the system represented in Fig. 1.
It will readily be seen that by this arrangement the same effect as to the
independency of the consuming circuits on each other is obtained as in the system
Fig. 1. Moreover, a certain saving of conducting material is obtained in as much
as the compensating conductor needs not be continued to the generating dynamo.
The arrangement represented in Fig. 3 will therefore be the more advantageous
the more the generating plant is distant from the series connected consuming
groups.
In the preceeding description the generating machine has been supposed to be
a bipolar one, but this has only been done for the sake of simplicity of the drawings
and it will readily be understood by any electrician that the invention can also be
made use of in combination with multipolar machine and with armature windings
of any description. Moreover, the invention is not limited to the use of but one
generating machine but it may also be combined with several generating machines
connected in parallel, which arrangement is well known equivalent for one generating
machine.
We are aware that attempts have been made to fed with current three conductor
systems by the aid of one common generating machine and we do not broadly claim
the use of such a common generating machine in combination with two series
connected groups of current consuming apparatus.
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 a system for distributing electricity to two series connected groups of
consuming apparatus by the aid of two main conductors and a compensating con-
ductor the combination, with the compensating conductor and a continuous current-
dynamo connected with the mains, of a coil of high self induction connected at both
ends with diametrically opposed points of the armature winding of said dynamo,
and in its centre with the said compensating conductor, as and for the purpose
stated.
2. In a system for distributing electricity the combination with two series
connected groups of current consuming apparatus, two main conductors, a com-
pensating conductor and one continuous current generating machine or its described
equivalent, of a coil of high self induction connected at both ends with diametrically
opposed points of the armature winding of the generating machine and connected
in its centre with the said compensating conductor, as and for the purpose
stated.
3. In a system for distributing electricity the combination with two series
connected groups of current consuming apparatus, two main conductors, a com-
pensating conductor, a continuous current generating machine and a compensating
machine running as an electro motor, of a coil of high self induction connected at
both ends with diametrically opposed points of the armature winding of said

page_text: compensating machine, and connected in its centre with the said compensating
conductor, as and for the purpose stated.
D
1000
J. H. JOHNSON & Co.,
Agents.