Improvements in Electro-magnetic Induction Apparatus for Trans- formers, Generators, or Motors.
Year: 1889

page_text: Date of Application, 29th Oct., 1889-Accepted, 25th Oct., 1890
Improvements in Electro-magnetic Induction Apparatus for Trans-
formers, Generators, or Motors.
1, LOUIS BOLLMANN, an Engineer of Vienna II Obere Donaustrasse 93, in the
Empire of Austria, 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 :-
In my Specification No. 14161 of 1888 I have described methods of producing
electro magnetic inductions and applications of these methods to transformers,
generators, or motors.
My present invention relates to improved apparatus for this purpose, as I shall
describe referring to the accompanying drawings. But in order that my present
invention may be more clearly understood I may premise that in my previous
Specification above referred to I described the action of certain parts therein termed
magnetic locks, which might be either of two kinds.
A lock of the one kind is a moveable piece of iron which in one position forms
part of a magnet and in another position makes a break of the magnet so that as
the magnetic circuit is thus closed or opened, electric currents are induced in coils
surrounding the magnet or parts of it. A lock of the other kind is also a piece of
iron forming part of a magnet but of smaller diameter than the body of the magnet
itself, and surrounded by a coil through which electric currents can be transmitted
in either direction. When they pass in the one direction the magnetic circuit is
virtually closed; when they pass in the other direction, that circuit is virtually opened.
Thus by alternations of current in the coil of the lock, which remains itself stationary,
inductions are caused as in the case where a moveable lock of the former kind is
employed. In applying such locks to transformers for converting a continuous
current into a continuous current of different tension or for converting an alternating
into a continuous current, I employ a number of instruments of the kind shewn in
elevation by Fig. 1. P is an electro magnet in the form of a massivo iron bobbin
with projecting parts, as shewn in the sectional plan on line ZZ at Fig. 2, and having
a coil for the continuous primary current rendering the ends of the bobbins
respectively north and south poles. A is a horse shoe core formed of iron wire with
flat polar ends of which the one is connected to the upper flange of P and the
other to the lower flange with the intervention of magnetic locks C¹(". This
core is wound with the secondary continuous current coil a like other similar
instruments.
The secondary coils a of all instruments making up the transformer are interposed
in series into a common secondary circuit, and by seriatim producing undulations in
the magnetic state of the soft iron cores A surrounded by the said secondary coils,
current waves are produced, the rapid succession of which constitutes the continuous
secondary current. For producing the said undulations in the magnetic state, the
poles of the secondary cores A are alternately connected to poles of contrary and
the same names.
As the magnetic polarity of the secondary cores A must always remain unaltered,
the action of the primary poles on secondary poles of the same name should never be
so long continued as to reverse the polarity of the secondary cores.
Assuming the locks CC¹¹ to be as at Figure 1 and that a primary continuous
current passes through the coil p, while a secondary current wave, induced in another
of the instruments constituting the transformer, flows through the secondary coil a
in such a direction as to form a south pole of A in front of the north pole of P and
a north pole of A in front of the south pole of P₁, the whole forms a closed ring
which is simultaneously magnetised by both currents whereby their energy is partly
consumed.

page_text: As soon as the degree of saturation is reached which corresponds to the current
in a alone, the connections between P and A are reversed by removing the
locks CC and introducing others in the spaces (11 C. The electric currents in a
and P are now, relatively to the magnetic circle, opposite to each other, and this
interrupts the continuity of the magnetic circuit. The core A becomes therefore
partly demagnetized by the influence of the opposite magnetism excited in it by
the reversed connections with the primary magnet P, and thus again a part of the
energy of the primary current in p is consumed.
This accelerated demagnetisation produces in the coil a an induction in the same
direction as that of the secondary current flowing in it, which reinforces that
current by the energy consumed in the primary current during the magnetisation
and demagnetisation of A and also returns to it that little energy, which has been
contributed by it during the magnetisation, so that the entire energy consumed in
the primary current in p is transferred to the secondary current in a.
Instead of employing moveable locks stationary automatic electro magnetic locks
may be employed in practice. In order to attain the requisite alternating currents
for these locks, there may be provided on each core A of a number of such connected
instruments, a small separate induction coil in which an alternative current is
induced by the successive increases and decreases of magnetism.
As at the end of every wave of the alternative current induced in this way and
designed to be passed through the magnetising coils of the electro magnetic locks,
the intensity of the said current so considerably decreases that the locks would be
unable to withhold the magnetism excited by the primary current from short
circuiting through the cores of the locks and as this would take place before the
increase or reduction of magnetism has reached the requisite point, it is necessary to
prolong the action of the locks.
For this purpose, every lock is provided with two separate magnetising coils, one
of which is interposed into the circuit of the alternative current generating coil of
the same instrument and the other into the said circuit of a neighbouring instru-
ment, in which the changes of the direction of the current take place at other
moments.
One instrument thus regulates and times the action of the other, so that the
inductions of the several coils must follow each other successively to produce a
continuous current.
To transform an alternating current into a secondary continuous current without
the use of the locks C, the magnets P and A of Figs. 1 and 2 may be connected
together, so as to form a closed ring with the primary coil p on one side and the
secondary coil a on the other side. In a flows the continuous secondary current
produced by combining several such systems, as above described.
In p flows the primary alternating current which must be a separate one for each
instrument so that the alternations of the several currents follow each other successively
to produce a continuous current.
When the alternating primary current flows in the coil p relatively to the circuit
in the same direction as the current in a, the magnetic circuit is closed and is
magnetized by the currents both in p and in a. When the current in p flows
opposite to that in a, the magnetic circuit is interrupted, and the magnetism
vanishes again, the energy of both opposite currents in p being transferred to the
current in a.
The primary currents should be of such strength relatively to the mass of iron
in the circuit, that they will be entirely consumed by the magnetisation and
demagnetisation.
The strength of these currents ought to be the same as those of the secondary
alternating currents which would be produced by a continuous primary current of
the strength of the secondary current in a, when the action is inverted for producing
alternating currents by a primary continuous current, as previously described.
In the transformers above described, electric energy is translated into electric
energy of another nature by alternately increasing and reducing the magnetising

page_text: ability of a soft iron core or cores surrounded by the primary and secondary coils,
the said increases and reductions being operated by changes in the connections of a
magnetic circuit formed by the said cores or cores, and these changes taking place
at the expense of part of the energy of the currents. Now, similar changes in the
connections of magnetic circuits may also be produced by mechanical power, in
which case the mechanical energy is, with the joint action of the residual magnetism,
transformed into electric energy, which is to say that dynamo electric machines can
be constructed on this principle.
When a number of similar magnetic circuits are so arranged as to be adapted
to be closed and broken seriatim and have their secondary coils interposed into the
same circuit, a continuous current will be generated as I will explain referring
to Fig. 3.
A A are several (6) horse shoe magnets fixed in a circle, their coils being
connected in series, and carrying the constant current produced. D is a star shaped
magnet with 10 poles, which are coiled in such a manner that a north pole always
follows a south pole as indicated by the signs
and +. This magnet is fixed on
an axis which rotates in the direction indicated by the arrow Z, its poles passing as
near as possible to those of the magnets A A.
The coils dare connected by means of two revolving discs and brushes either
directly or in shunt with the exterior circuit, so that the magnet D is kept constantly
magnetised and its poles form 10 rotating magnetic fields.
Assuming that a constant continuous current has already been in the outer
circuit and that all the magnets A and D are proportionately magnetised, if the
position of the poles be as in Fig. 3 the poles 1 and 2 of the field magnets D just
approaching those I and II of the magnet A', A¹ is then magnetised by influence,
at the same time as the magnetic circuit gradually closes, so that when the poles
are quite close to each other a closed or nearly closed circuit is obtained, and A¹,
partly by the magnetism of the poles of D, and partly by the current in the coils a
is magnetised until the iron is so far charged as to correspond to the closed circuit
and the current in a alone.
The poles 1 and 2 revolve past I and II and at the same time the poles 10 and 1
approach I and II. By this movement the circuit is again broken and in
consequence of the approach of the poles 10 and 1 to I and II and their opposite
polarity, the magnetism before excited in A¹ decreases rapidly till when the poles 10
and 1 are quite near I and II, A¹ becomes demagnetised.
The magnetism thus decreased in A produces an induction in the coils a which
is of the same direction as the current already in a and strengthens it.
The poles 10 and 1 then revolve past I and II, at the same time as the poles 9
and 10 approach them and thus the closing of the magnetic circuit and the
magnetising and demagnetising are repeated as above described.
When the magnetic circuit is closed the magnetising induces an electro motive
force in the coils a opposed to, but less than the current existing in them so that the
electromotive force of the current in a is reduced.
The construction of the machines can be altered in many ways. For example as
shewn in Figure 4 the fixed armature P may consist of insulated zigzag coils made
of one strip of iron.
These iron coils serve at the same time as magnet cores and as coils such as are
used in rotating iron armatures of known kinds."
Each radial part of the iron strips is magnetised and demagnetised by the
passing field magnet poles of alternate names, which, in this case, must be arranged
in one and the same plane, instead of being located in a cylindric surface as in
Fig. 3.
Since the magnetic axis of these strips is very short and since they may be
magnetised on both sides by revolving field magnets, this construction is very
efficient.
Each rotating pole covers always a number of such radial iron strips so that the
induction is completely uninterrupted.

page_text: The current is conducted at e and
to and from the ends of the continuous iron
strips which are arranged zigzag in a circle.
In certain cases the armature and the field magnets may be made stationary and
between them revolving soft iron pieces may be arranged for transmitting the
magnetism under these conditions no sliding electric contact takes place.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is:-
1. A transformer consisting of several instruments each constructed substantially
as described with reference to Figs. 1 and 2 and having their coils connected
for passage of electric currents suitably timed for effecting the required trans-
formation.
2. An electric generator or motor constructed and arranged substantially as
described with reference to Figs. 3 and 4.
Dated this 20th dor of Oatchan 1000
ABEL & IMRAY,
Agents for the Applicant.