Method for Obtaining Combined Alternating and Continuous Currents and Distributing the same for the Electrical Transmission of Power, particularly for Electrical Traction.
Year: 1898

page_text: Date of Application, 4th July, 1898-Accepted, 24th Sept., 1898
COMPLETE OF MUIFICATION.
Method for Obtaining Combined Alternating and Continuous Currents
and Distributing the same for the Electrical Transmission of
Power, particularly for Electrical Traction.
I, MAX DERI, of I Reichsrath-strasse 3, Vienna, Austria, Engineer, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed. to be particularly described and ascertained in and by the following
statement: —
The distribution of electrical energy by means of alternating currents, especially
by means of monophase alternating currents is accompanied by considerable
disadvantage for many purposes in spite of the great superiority in economy
of leads and of the ease with which the distribution can be regulated.
Accumulators cannot be charged with alternating currents nor can electrolysis
be effected by them, and in starting electro motors difficulties have to be over-
come.
By this invention the system of distribution combines in a simple manner
both kinds of current in a two or three lead system and renders possible the
simultaneous use of the advantages of both kinds of current.
From the central station an alternating current is sent out through the
primary leads. The secondary stations comprise alternating current trans-
formers and secondary generators of continuous current, such as accumulators
or transformers for converting alternating into continuous current. The
secondary generators for alternating currents and for continuous currents are
arranged in series or connected together.
Figure 1 of the accompanying drawings is a diagram of the combination of a
transformer with a continuous current generator, and Figure 2 is a diagram of
a transformer with an accumulator battery. In both cases the secondary coil
of the transformer and the continuous current generator are connected in series.
The terminal of the alternate current coil is designated by 1, that of the con-
tinuous current generator is designated by 3, and the terminal by which the
two generators are united (the connecting point) is designated by 2. The leads
connected with these terminals are lettered L¹ L2 and L³. L2 is required only
where the connecting combination is used.
It
Between the leads L1 and L2 there is an alternating pressure, between L³
and La continuous pressure and between L' and L³ a periodically undulating
pressure (wave pressure) consisting of the sum of the two other pressures. In
Figure 3 the character of the pressures is indicated diagrammatically.
follows that the separate leads will convey currents which,-as. may be repre-
sented in Figure 4-are in L¹ periodically alternating, in L³ continuous and
in L undulatory (wave current).
If a circuit with high degree of self induction is formed between L' and L³
the current therein will have shallow waves approximating to a continuous cur-
rent; if the circuit comprises a continuous electromotive force in a contrary

page_text: direction, such as might be obtained from a battery,. the current therein will
approximate to an alternating current; finally, if both self induction and
polarisation are present, the wave current will result.
In the last mentioned case the potential difference of the different parts of the
circuit may be given the character of the three different pressures, as may be
the kind of the resistance.
The state of affairs in the circuit between L¹ and L³ will be as described éven
if the connecting lead L2 is omitted.
The manner in which the combination of a continuous current with a poly-
phase alternating current is made, is indicated in Figures 5 and 6. In Figure 5;
1-2 is the transformer coil of the one phase and 2-3 the series circuit formed
of the transformer coil of the other phase and of the continuous current source.
Between 1 and 2 there will be an alternating pressure, between 2 and 3 an
undulatory pressure.
In Figure 6 the continuous current source is in the connecting lead so that
there is an undulatory pressure between 1 and 2 as well as between 2 and 3
but in opposite senses as the diagram shews.
If at different positions of a three or two lead system, such as has been
described, converters of alternating into continuous current are introduced so
that every alternate current motor and its accompanying continuous current
machine are arranged in series or connected together, and as shewn in Figure 1,
the terminals 1 and 3 being connected with the leads L' and L³ and the middle
terminal 2 with the connecting lead L2, the converter will be driven by an
alternating current between 1 and 2 and will give rise to a continuous pressure
between 2 and 3; it can however take current from both sides simultaneously
and thus operate as an alternating and continuous current motor combined.
A number of converters arranged in this way can maintain in the leads a
continuous pressure besides furnishing motive power, and if in addition
accumulator batteries are introduced between L2 and L³ at suitable positions,
these can be charged and discharged and thus, as buffer batteries, regulate the
pressure and equalise the output of energy. By a system of leads in which a
large number of electromotors are driven, alternating and continuous currents
can be distributed according to the foregoing combination, if electromotors
combined in the manner of converters are used and buffer batteries are applied
for equalisation.
In Figure 7 is shewn a diagrammatic view of a current distribution in
accordance with this invention.
From the central station C the primary alternating current leads pass to the
interposed transformers T. The secondary stations are arranged as follows:-
I, two transformers TT and a battery B; II, a transformer T and a continuous
current generator G driven by primary current; III. a transformer T and a
battery B.
The secondary circuit is formed partly as three leads for the different kinds of
current and partly as two leads for the continuous current and partly as two
leads for the wave current. On the three-lead circuit is a consumer's installation
in D, an alternate and continuous current motor Ma and Me. From the con-
tinuous current two-lead circuit are fed in D₁, a battery B; in D₂, an electro-
lytic cell P; in D3, an arc lamp A in D₁, a continuous current motor Mc. On
the wave-current two lead circuit are in D, are lamps in series A A; in D, an
alternate and continuous current motor Ma, Mc, in Ds, a resistance R in series
with a self-induction S for obtaining continuous current; in D, a battery B
in series with a self induction S for obtaining alternating pressure between 1-2
and continuous current between 2-3.
1'
The distribution of current according to this system is particularly appropriate
for electric traction, which may for example be effected according to the follow-
ing arrangement. Along the railway track are laid three leads L1 L2 and L³,
Land L are connected with transformers and conduct alternating current to

page_text: the car-driving mechanism. At certain points accumulators are connected with
the leads L2 and L. One of the leads can be constituted by the rail and the
earth. The motor of the car consists of an alternating and continuous current
motor or an alternating and continuous current converter. In this combined
mechanism the alternate current armature and the continuous current armature
are connected in series. By contacts the alternate current motors on L' and L³ and the
continuous current armatures on L³ and L3 are put in circuit. The motor
mechanism is put in motion at starting by the continuous current, but after
attaining a certain degree of speed it is driven chiefly by the alternating
current.
The continuous current motors of the motor mechanism are connected with
each other and with the batteries in parallel circuit by the leads L2 and L³, so
that there is in these leads a certain driving pressure by means of which one
part of the motor mechanisms yields a continuous. current during the journey
and, if necessary, also when the car is stopped, to another motor, for instance
of a car which is starting or travelling up an incline. In the same way, buffer
batteries receive and deliver continuous current and effect an equalisation of the
output of work from the separate trains.
The leads L and L³ can also be divided into several sections; to a certain ex-
tent also, one or other of these contact leads can be omitted; for example, in
stations; where the train travels by the power of the continuous current, the
alternating current contact lead, and in the open track, where the alternating
current chiefly is used, the continuous current contact lead may be eliminated.
Under the previously mentioned conditions the middle, common lead L² may
be to some extent, or entirely omitted. There will then be a wave pressure
between the two contact leads which on the one hand is fed through the trans-
formers and batteries connected in series, and with which on the other hand
the combination car-motors connected in series will be in circuit.
In this system the travelling motor mechanism itself effects the conversion
of the alternating current into continuous current, but under certain conditions
it may be useful to employ separate stationary converters or when the central
station is in an appropriate position, continuous current generators in addition
to the general continuous current supply may be used.
The accumulators are, as a rule, stationary. But buffer batteries connected in
parallel circuit-or for special purposes batteries otherwise connected may be
also carried with the train.
Starting from the arrangement shewn in Figures 5 and 6, traction installa-
tions can be supplied with polyphase alternating currents combined with con-
tinuous currents without using more than three contact leads (one of them, if
necessary, a rail as a return lead) which may be connected with the different
current sources either as in Figure 5 or as in Figure 6 and using combined
motors in the train driven simultaneously from both current sources, or it may
be alternately from one or the other source.
Figure 8 is a diagram shewing, by way of example, the current distribution
for traction with three leads as a combination of monophase alternating current
with continuous current.
C is an alternating current generator, L L are the primary alternating cur-
rent leads, T are transformers, B are accumulators. The secondary leads, in
this case the contact leads L1 L2 L³, conduct alternating current, continuous
current and wave current.
The secondary station II comprises a transformer, III comprises an accumula-
tor, while I and IV comprise both transformer and accumulator. In the last
two the secondary coil of the transformer and the battery are connected with
each other, and the terminals 1 and 2 of the transformer and the terminals 2
and 3 of the battery are connected with the rail leads L1 L2 and L³, these
terminals and leads being connected which bear the same number. F, and F
are railway trains the contacts of which are in connection with the three leads.

page_text: 2
On F₁ there is an alternating current motor Ma and a continuous current
motor Mc; on one of the axes of F, there is a twofold machine, a converter Ma. c.
The manner in which by this arrangement the combined motor mechanism
functions now as a double motor, now as a converter, and in which the pulsating
battery equalises the out-put of work will be easily understood from the fore-
going explanation.
The applications of this combined current distributing system are not ex-
hausted by the foregoing description and diagrams; there are still possible
numerous variations in application to the different forms of electric transmission
of power particularly for purposes of traction.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. A method for obtaining combined alternating and continuous current, that
is to say, electrical energy in the form of a combination of monophase, or poly-
phase alternating current with continuous current, by arranging in series, or
connecting together alternating current transformers and continuous current
secondary generators, of which the electromotive force is added together in such
a way that between two leads of the series a pressure giving rise to wave currents,
or between the two leads external to the connecting lead a pressure giving rise
to wave currents is produced, while between the one external lead and the con-
necting lead an alternating pressure and between the other external lead and
the connecting lead a continuous pressure is produced, substantially as described.
2. A method of distribution of combined alternating and continuous current,
obtained by the method referred to in Claim 1, by secondary stations controlled
from alternating current generators by means of primary alternating current
leads, which stations comprise alternating current transformers and continuous
current secondary generators arranged in series or connected together, and by
distributing leads extending from the secondary stations either in a three lead
or a two lead system, to which leads the current consuming apparatus are con-
nected either between L1 and L2 or L2 and L3 or between L¹ and L³ according
as the apparatus consists of parts which exert alternating or continuous counter-
pressure and as they use chiefly alternating current energy or chiefly continuous
current energy or both kinds of current energy in their different parts, sub-
stantially as described.
3. A method of distribution, suitable for electric traction, of combined alter-
nating and continuous current, obtained by the method referred to in Claim 1,
by three leads, of which two (L¹ and L³) are connected with alternating current
transformers and two (L2 and L³) with accumulators, or by two leads (LI and L³)
which are connected with current sources consisting of transformers and accumula-
tors connected in series to which three or two leads railway trains are connected
by means of contacts, such trains being provided with alternating current motors
and continuous current machines or converters from alternating to continuous
currents, which combination of motor mechanism being brought into contact in
the first case with L1 L2 and L3 and in the second case with L2 and L³, can be
driven by alternating current and continuous current alternately or by both
sources of current simultaneously, or, being driven by alternating current can
deliver continuous current into the leads, substantially as described.
Dated this 4th day of July 1898
ABEL & IMRAY,
Agents for the Applicant.