Improvements in Electrical Induction Apparatuses or Transformers.
Year: 1889

page_text: Date of Application, 5th Dec., 1889
Complete Specification Left, 11th Aug., 1990-Accepted, 18th Oct., 1890
PROVISIONAL SPECIFICATION.
"
Improvements in Electrical Induction Apparatuses or Transformers.
We, MICHAEL VON DOLIVO-DOBROWOLSKY, Engineer, and the Company
"ALLGEMEINE ELEKTRICITÄTS GESELLSCHAFT a Joint Stock Company entered
according to the German Laws in the Register of Trades both of No. 26 Schlegel-
strasse Berlin, Prussia, do hereby declare the nature of this invention, whereof the
said Von Dolivo-Dobrowolsky is the inventor, to be as follows:--
Our invention relates to electric induction apparatuses, or transformers, whereby an
alternating current of given tension is converted into a current of different tension,
and its object is to raise the useful effect of such apparatuses.
13
The apparatuses of this kind as heretofore employed, consist substantially in two coils,
one for the primary and one for the secondary or induced current, and a core or
envelope of iron, common to both coils, which is magnetized by the action of the
primary current, and whereby the strength of the magnetic field of the latter is
increased. The magnetism thus produced is alternating like the primary current, i.e.
the polarity of the core is rapidly changed by every alternation of the current, one
half of each phase of the same producing a north pole at one end and a south pole at
the other end of the core, while the other half phase produces poles of opposite
denomination. By this constant and rapid changing of the poles a considerable
portion of the energy of the primary coil is uselessly converted into heat and
consequently wasted.
For the purpose of avoiding this loss of energy we proceed as follows. A plurality
of pairs of coils, each pair consisting of a primary and a secondary coil, are placed
upon as many cores of iron, forming three or more closed or nearly-closed magnetic
systems and preferably arranged in a circle, and the primary coils are connected to
a dynamo-electric machine, which produces a number of alternating currents, whose
phases are shifted in respect to each other by a fraction of a phase, so that the
maximum impulsions acting in the individual coils, succeed each other, and which
currents, on leaving the dynamo, unite to form a single current or groups of currents.
Preferably, the coils are placed in the same order in which the phases of the different
currents whereby they are excited, follow one another. Under these conditions the
total amount of magnetism in the system of combined cores will always be the same,
while the magnetic axis is continuously shifted forward. The magnetism of each core
consequently increases and decreases, and changes its polarity with comparative slow-
ness, so that the heating of the cores and loss of effect is considerably reduced
The means for producing currents of the said kind may be such as are set forth in
the specification of another patent-application of mine, filed on the same day as the
present one.
D
.
1000
COMPLETE SPECIFICATION.
Improvements in Electrical Induction Apparatuses or Transformers.
We, MICHAEL VON DOLIVO-DOBROWOLSKY, Engineer, and the Company
"ALLGEMEINE ELEKTRICITÄTS-GESELLSCHAFT," both of No. 26 Schlegelstrasse, Berlin,
Prussia. do hereby declare the nature of this invention, whereof the said Von
Dolivo-Dobrowolsky is the inventor, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement:
Our invention relates to electric induction apparatuses, or transformers, whereby an

page_text: +
alternating current of given tension is converted into a current of different tension,
and its object is to raise the useful effect of such apparatuses.
The apparatuses of this kind as heretofore employed, consist substantially in two
coils, one for the, primary and one for the secondary or induced current, and a core or
envelope of iron, common to both coils, which is magnetized by the action of the
primary current, and whereby the strength of the magnetic field of the latter is
increased. The magnetism thus produced is alternating like the primary current,
e. the polarity of the core is rapidly changed by every alternation of the current, one
half of each phase of the same producing a north pole at one end and a south pole at
the, other end of the core, while the other half phase produces poles of opposite
denomination. By this constant and rapid changing of the poles a considerable portion
of the energy of the primary coil is uselessly converted into heat and consequently.
wasted.
For the purpose of avoiding this loss of energy we proceed as follows. A plurality
of pairs of coils, each pair consisting of a primary and a secondary coil, are placed
upon as many cores of iron, forming three or more closed or nearly-closed magnetic
-systems and preferably arranged in a circle, and the primary coils are connected to a
dynamo-electric. machine, which produces a number of alternating currents, whose
phases are shifted in respect to, each other by a fraction of a phase, so that the
maximum impulsions acting in the individual coils succeed each other, and which
currents, on leaving the dynamo, unite to form a single current or groups of currents.
Preferably the coils are placed in the same order in which the phases of the different
currents whereby they are excited, follow one another. Under these conditions the.
total amount of magnetism in the system of combined cores will always be the same,
while the magnetic axis is continuously shifted forward. The magnetism of each core
consequently increases and decreases, and changes its polarity with comparative slow-
ness, so that the heating of the cores and loss of effect is considerably reduced.
The means for producing currents of the said kind may be such as are set forth in
the specification of another patent-application of ours, filed on the same day as the
present one, vizt. No. 19554 of 1889.
In the annexed drawing Fig. 1 is a sectional view of a transformer of our invention
with a dynamo for producing alternating currents of continuously-shifting phases.
Fig. 2 is a diagram serving to explain the operation of the latter.
A, B, C, Fig. 1, are three iron cores, a, b, c three primary coils and a, b, c¹ three
secondary coils placed on the respective cores A B C. The said cores are connected
together at one end directly, and at the other end by means of the hars E, so that
three closed magnetic circuits are formed, which are indicated in the figure by the
broken lines 1, 2, 3. F is a dynamo, connected to the coils a, b, c by the respective
wires a², b², c², and which produces alternating currents whose phases of vibration are
shifted in respect to each other by one third of a phase, as shown by Fig. 2, in which
the wave-line a³ indicates the vibrations and phases of the current generated in one of
the coils of the dynamo, and the lines ³ ³ those of the second and third currents
induced in the other two coils of the said dynamo; the parts of the wave-lines above.
the horizontal line y representing the positive portions of the currents, and the parts
below this line the negative current portions. The machine by which these currents
are obtained will not be described here, as it does not form any part of our present
invention.
Supposing now the coils a, b, e to be arranged in such manner that a positive
current circulating in any one of them, will produce a north-pole at the outer end of
the core of the same, and starting from the moment indicated on the line qr, Fig. 2,
by point g, the condition in which the apparatus is at the time will be the following.
The first current represented by the wave-line a³ is at its positive maximum, measured
by the ordinate g h, while the currents 63 and c³ are negative and of the inferior but
equal strength determined by the line gi. The coil a therefore produces a strong
north-pole at the outer end of the core A and the coils b, c south-peles of less but
equal force at the outer ends of the cores BC. The resultant magnetic centreline,

page_text: or magnetic axis of the system of cores, will therefore, in this case, pass lengthwise
through the core A and in the middle between the cores B and C, as indicated by the
line N S Fig. 1, N and S being respectively the north-pole and the south-pole. At
the next moment, indicated by the point j, Fig. 2, the positive current a³ has decreased
and the negative current c³ las increased in strength, so as to be proportionate to the
respective ordinates j, k and j, 1 (which are equal, while the current 63, being at its
changing-point from negative to positive, is zero. Consequently there is then a nort'ı--
pole at the outer end of core A and a south-pole at the outer end of core C, while
the core B is not acted upon by the coil . The magnetic axis will therefore have the
position N' S¹. At the moment indicated by point m, Fig. 2, the negative current c³
is at its maximum measured by ordinate m o, the positive current a³ has decreased
further so as to be proportionate to the ordinate mn, and the current 63 has become
positive again and is of like strength as current a³. There will therefore then be a
strong south-pole at the outer end of core C, and north-poles of lower but equal
strength at the ends of the cores A B. This causes the magnetic axis to assume the
position NS2. The said axis is thus continuously shifted forward, or rotated about the
centre of the magnetic system. Besides, if the collective strength of all the currents
is maintained uniform, as is actually the case in our arrangement, the total value of the-
magnetism produced thereto will be the same at every moment.
By the said shifting of the magnetic axis currents are induced in the secondary
coils ac, which may be employed either separately or conjunctively.
It is evident that the described transformer may have any number of cores from
three upward; but there must be at least as many cores as there are alternates.
currents acting on the same.
In Fig.
the primary and secondary coils are shown arranged in juxtaposition..
They may, however, also be placed one around the other, and instead of being located
on the cores A, B, & C, they may be disposed on the peripheral bars E, as shown by
Fig. 3. The only difference in the latter case is that the distribution of the poles of
the cores relatively to the coils will be modified. Moreover, the body of iron forming
the system of cores, may be made in two or more pieces placed close to, or in contact
with each other. Thus, for instance, it may be divided on the lines p, p, Fig. 1, and
in such case the magnetic system, instead of being a perfectly closed one, may be.
called nearly closed.
In consequence of the described construction of our improved transformer and of its
combination with a machine for producing alternating currents of shifted phases, the
total amount of magnetism present in the magnetic system remains constant and the
polarity of the system is changed comparatively smoothly. The energy required for
such changing is therefore less, a considerably smaller amount of energy is lost by
conversion into heat, and a higher useful effect is obtained.
For the purpose. of securing the best effect it is, however, necessary to provide
means for avoiding Foucault or eddy currents by constructing the aforesaid cores of
thin iron plates, or in other known manner.
Having now particularly described and ascertained the nature of this inven-.
tion and in what manner the same is to be performed, we declare that what we
claim is:
An induction apparatus consisting in a number of cores of iron forming together
three or more closed or nearly-closed magnetic systems, primary and secondary coils
placed on said cores, electric circuits connected to the primary coils, and means for
creating in the said circuits alternating currents of successive phases, for the purpose
of causing a continuously-progressive shifting of the magnetic axis and maintaining.
nearly constant the total amount of magnetism, substantially as described.
Dated the 11th dovod 1000
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, W.C., Agents.