Converters for Single Phase Alternating Currents.
Year: 1899

page_text: Date of Application, 14th Jan., 1899-Accepted, 4th Mar., 1899
COMPLETE SPECIFICATION.
Rotary Converters for Single Phase Alternating Currents.
I, MAX DERI, of I Reichsraths Strasse, No. 3, Vienna, Austria, Electrician, 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:-
The rotary converters for transforming single phase alternating currents into
continuous current, or the converse, unlike those for polyphase currents, have not
proved advantageous because the resulting magnetic field and the electromotive
forces are not constant, and because the armature reaction prejudicially affects the
useful effect, the efficiency and the sparkless working of the apparatus.
By the arrangements which form the subject of the present invention I have
succeeded in obviating the said disadvantages.
I will describe my said invention with reference to the accompanying drawings
which shew various examples of the manner of carrying out the same.
Fig. 1 shews a diagrammatic view of a machine whose rotor is in the form of
a gramme ring A A in whose continuous winding alternating currents are intro-
duced at a a and b by means of the contact rings and r¹. F F is a stator of
iron (which may be laminated) in which are provided short circuited windings s s.
By means of four brushes B B currents can be taken from the rotor.
The machine is shewn with four poles, and this number will be assumed by way
of example in the following description.
If the armature A excited by single phase alternating currents be rotated
synchronously with the periods of the alternating current within a stator F pro-
vided with a short circuited winding, there is produced, in consequence of the
reaction of the currents induced in the short circuited windings, a constant
magnetic field which is stationary relatively to the stator.
By the rotation in this field there are produced in the windings of the armature
alternating electromotive forces in such manner that between any winding sections
situated at a certain angle to each other for example between the axes e e and a a
or d d and there occur potential differences with shifted phases. The phase
difference is determined by the angle a which the said axes ce and aa or dd
and enclose between them.
At the periphery of the armature or of the collector C which, as in ordinary
continuous current dynamo machines, is connected to the armature windings; there
consequently appear alternating electromotive forces of equal maximum value
whose phases correspond with all angle values of the periphery.
If therefore the brushes B B are adjusted to the position of the maximum electro-
motive force there can be led off from the armature through them, continuous
currents while the detrimental armature reactions are obviated as in polyphase
transformers

page_text: The armature through which the alternating currents flow, will, if it previously
has a suitable speed imparted to it, rotate by itself in the short-circuited stato
with a sub-synchronous speed like the rotor of an induction motor. In order
to produce the requisite synchronous motion of the rotor, a synchronous electro-
motor is used except in the case when the shaft of the alternate current generator
can be employed directly for driving. This motor insures the synchronous
rotation of the rotor without any appreciable expenditure of force, and it need
therefore be of only very weak power.
Figs. 2 and 3 shew the arrangement in front view and longitudinal section, in
which the small synchronous motor M whose armature A' is supplied from the
same source of alternating currents as the converter U, is rigidly connected to
the rotor of the latter.
The field magnets F1 F1 of the synchrous motor are excited by continuous
currents in the usual way, which currents can also be taken from the converter
itself.
In Figs. 4 and 5 is shewn a simplification of the synchronising device. In this
case the sychronous motor is combined with the converter so that the armature A
fulfils the function for both and the stator F F carries, in addition to the short
circuit windings ss, the continuous current exciting winding e e (with polar
arrangement). In this arrangement the excitation is effected by the continuous
current drawn from the converter and for example the winding e e is in shunt
circuit with the armature.
Fig. 6 shews sections of the stator, indicating how, in the case last described,
the two windings of the stator may be in one groove, while Fig. 7 shews them in
separate grooves; in both figures s represents the short circuit winding and c the
wire for the continuous current excitation. The windings, may, however, be
arranged in diverse other ways, either one over the other or side by side.
For the short circuit winding, rods may advantageously be employed, but any
kind of wire winding will serve, and such winding may be so arranged that any
desired groups may be united to form closed circuits, and in certain cases the
arrangement may be such that resistances, condensers, or the like may be included
in the circuit.
The construction of the converter may also be reversed, so that the rotor carries
the short circuit windings and also, if it is not driven by a special synchronous
motor, the excitation winding, while alternating current is supplied to and con-
tinuous current drawn from, the stator. In this case the stator must carry a
stationary collector and the brushes must be attached to the axis of the rotor with
which they must rotate synchronously.
It is obvious that the construction described can be used also in the reverse
sense for transforming continuous current into single phase alternating currents.
Any number of poles and any known construction of dynamo armatures and
short circuit armatures as well as of synchronous motors can be used.
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed I declare that what
I claim is:-
1. A rotary converter for transforming single phase 'alternating currents into
continuous current or the reverse consisting of a rotor like a continuous current
dynamo armature connected on the one hand with a collector on the other hand
with contact rings and rotating within an iron stator provided with short circuit
winding, the said armature being rotated synchronously by means of a synchronous
motor rigidly connected with it, substantially as described.
2. A rotary converter for transforming single phase alternating currents into
continuous current or the reverse, consisting of a rotor like a continuous current
dynamo armature connected on the one hand with a collector, on the other hand
with contact rings and rotating within an iron stator provided with short circuit

page_text: winding and also with exciting windings to produce by means of continuous
current a constant magnetic field which by co-acting with the armature keeps the
said armature in synchrous rotation substantially as described.
Dated this 14th day of January 1899.
ABEL & IMRAY,
Agents for the Applicant.