US2276051A - Regulating transformer - Google Patents

Description

March 10, 1942. I cs. LEISCHNER 2,276,051

REGULATING TRANSFORMER Filed Aug. 23, 1939 3 Sheets-Sheet l 7/6 Ila #6 Fig.5.

6 I06 Ila amh y 1942! G. LEISCHNER REGULATING TRANSFORMER Filed Aug. 23, 1939 3 Sheets-Sheet 2 Jaye/7 51561304426,

Y 3 Sheets-Sheet 3 Mizmsa March 10, 1942.

@. LEESCl-ENER REGULATING TRANSFORMER Filed Aug. 25, 1959 Patented Mar. 10, 1942 UNITED REGULATING TRANSFORMER George Leischner, Bonigen, near Interlaken, Switzerland Application August 23, 1939, Serial No. 291,625 In Switzerland February 10, 1939 4 Claims.

The invention relates to a regulating transformer, in which the bare surface of a singlelayer regulating winding serves as collecting means for the current. Such regulating transformers have already been suggested. In certain embodiments the electric current collector, consisting of a single conductor, surrounded a main core and magnetic return paths. The size of the regulating steps depended on the number of these return paths and thus, if there were many steps, very complicated main-cores resulted, which infiuenced the economy of the transformer unfavourably.

In the present regulating transformer the current-collector also surrounds the regulating winding and the main-core, and is subdivided at several places by insulating joints. If this ourrent-collector is annular and is driven, for instance, by eccentrically arranged spindles or shafts, it follows a circular path around the core axis and is moved along the regulating winding in a translatory motion. If such spindles or shafts are used, the up and down movement per revolution of the spindle corresponds to the pitch of the regulating winding. In this manner the bare surface of this regulating winding is always and successively touched at one point in both directions of motion. If an annular collector is used the transmission of the variable voltage is effected with contacts coming alternately into action. These contacts, which may be differently shaped in accordance with the type of transformer, are connected with each other and with impedances in such a Way, that the short-circuit currents occurring during the switching operation are damped out. These impedances, which come into action at the passing from one part of the collector to the other, may be chocking coils or may be formed by a part of the means leading the current away, said part being located within the iron of the transformer. In the latter case a special shaping of the core is not necessary. Thereby, contrary to the regulating transformers with annular collectors, mentioned in the preamble as already known, the distribution of entire core portions or return paths in the direction of the path of the lines of force is avoided. Any core having a magnetic return path may be used for the construction of these transformers. Also by making use of the characteristic of the invention the construction of threephase regulating transformers with normal three-limbed cores becomes possible. The regulation is eifected in all cases by including or cutting out portions of the winding. If a two-part collector is used half turns are cut out and in the case of a collector with more than two parts a fraction of a turn is out out corresponding to the number of said parts. The size of the regulating steps may, therefore, be chosen at will.

The drawings represent several embodiments of the invention.

Fig. 1 is a front elevation of a single-phase regulating transformer;

Fig. 2 is a section on line II-II of Fig. 3,

Fig. 3 is a section of the same transformer on line III-III of Fig. 1.

Figs. 4, 5 and 6 show the same parts as Fig. 3 but in different positions of the current-collector.

Fig. 7 is a detached cross-section of the collector, taken on the line VII-VII in Fig. 3;

Fig. 8 is a cross section analogous to that of Fig. 3, showing a regulating transformer with four-part collector.

Fig. 9 is a detached section of the collector by itself used in the transformer shown in Fig. 8, the section being taken on the line IX-IX of Fig. 8.

Fig. 10 shows another embodiment of the core of a transformer with a four-part collector;

Fig. 11 shows the electric connections of the strips cooperating with the collector and choking coils arranged on the outside of the transformer,

Fig. 12' shows schematically a four-part collector with a special shaping of the leading-away strips.

Fig. 13 is a sectional plan View of a modified collector arrangement.

Fig. 13a is a front elevational view of a regulating transformer embodying the collector shown in Fig. 13.

Fig. 132) is a vertical sectional view of the transformer shown in Fig. 13a.

Figs. 14 and 15 show special embodiments of contact-devices, electrically connected with the collector.

The regulating transformer shown in Fig. 1 has a core I and a single return path 2. The primary Winding 3 is formed as a cylindrical winding and the regulating winding 4 as a single-layer winding with bare surface. The collector '5 is a ring. In this embodiment the collector 5 is subdivided into two electrically independent halves 5a and 51) by means of skewed or saddle-like joints filled with insulating material. But regarded mechanically, the collector forms a self-contained body. The inside diameter of the collector 5 is somewhat larger than the outside diameter of the regulating winding 4. With the aid of eccentrically arranged and synchronously rotating spindles, held in insulated bearings l', the collector 5 is moved in a winding-motion along the surface of the regulating winding. This collector can, therefore, successively make contact with all the points of the regulating winding.

Contact members 8 are arranged on the collector 5 diametrically opposite to each other and are insulated from the other parts of the collector by insulation 9, each member being electrically connected by means of conductors l0 with one of the annular halves 5a and 5b of the col lector.

Parallel to the core and fastened in the insulated bearings I are contact strips 1 I, with which the contact members 8 of the collector alternately cooperate.

These contact-strips H are electrically connected with each other by means of the conductor l2. This conductor passes through the wound core I of the regulating transformer and is provided at its centre with a tap leading through the core-iron to the outside. Tap [3 serves for leading the current away from the contact strips H to a (non-represented) terminal of the transformer, while one end of the regulating winding 4 is lead to the other terminal.

Figs. 3, l, 5 and 6 illustrate the mode of operation of the regulating transformer and show different positions of the collector which are repeated at each convolution of the winding.

In the position shown in Fig. 3 the collector lies with the half Ed on the upper side of the regulating winding, while the contact 3a, which is connected by means of the conductor Illa with the half 5a of the ring, touches the contact strip l'la, thus establishing a connection between the regulating winding and the stationary terminal by means of the conductors l2 and i3. In this position the part Eb of the collector has just left the regulating winding 4, but has afterwards been disconnected from the contact strip I lb by means of contact 82) and the switch-connection lob.

Fig. 4 shows the next phase of the regulating operation. The spindles l5 have been rotated through 90 from the positions shown in Fig. 3. Thereby the collector 5 is pressed against the right side of the regulating winding, so that both parts to and 51) come into contact with the bare surface. By this progressive motion contact 317 has come into contact with the contact strip l lb. A short-circuit takes place through the switch connection l2, the current of said short-circuit surrounding one half of the core iron and suppressing the magnetic flux therein. Both halves of the collector 5 touch the regulatin winding and the operating current flows through the conductors lfia and till) to the contacts 8a and 8b, through the contact strips la and lib. through the connection l2 to the tap i3 to the terminal.

When the position shown in Fig. 4 changes to that shown in Fig. 5 contact lid is lifted off from the contact strip Ha, the collector portion lying directly under said contact st 'p, comes into contact with the regulating winding the contact 8?) is moved into connection with the contact strip l lb.

In the position shown in Fig. 6 both halves and 5b of the collector make contact with the regulating winding on the left side, whereby a short-circuit takes place through the connection l2, the current of said short-circuit flowing around the one half of the core iron and suppressing the magnetic flux in half. Half of the current flows through the connections i05 and i017, the contact strips lid and ill) and the connection l2 to the tap til.

Fig. 8 shows a regulating transformer which differs from the embodiment shown in Figs. 1 to 6 in that it comprises a four-part collector. The same references indicate corresponding parts of the two embodiments. The contacts l5 have the form of loops. They may be made in one piece with the portions l5 of the collector. During the regulating operation the contacts l5 are pressed alternately with their inside surface against the contact strips H after the corresponding collector portions l6 have previously touched the regulating winding.

The core of this regulating transformer is divided into four parts. Therefore, only the fourth part of the magnetic flux is suppressed by the short-circuit taking place on the occasion of the switching operation.

The conductor l8 may also here, and in general, in the case of two and more than two subivisions of the collector, be led at different places through the core of the transformer. Thus a weakening of the active iron at one place is avoided.

Fig. 10 shows another manner of placing the conductors l8 connecting the contact strips l'l. Such a traversing of course, be made at any place of the transformer. The ends I9 are connected with contact strips l'i. When passing from one collector portion to the other, one fourth of the magnetic flux is suppressed at the spot in question.

The variation of the flux on cutting out and throwing in portions of the winding has an effect similar to that of a choking coil. In a transformer of the present type and structure the aforesaid suppression of the flux can, therefore, be omitted and a choking coil can be used in its place in order to damp out the short-circuit currents.

Fig. ll shows schematically a choking coil which is connected to the contact strips i? of a regulating transformer as shown. in Fig. 8. The current is led away at the junction point 26. This choking coil 2! replaces the connecting conductors The traversing holes in the core of the transformer I can be omitted.

In a regulating transformer of the kind first described only a two-part choking coil with tapping in the centre is necessary. the outer ends of the coil being connected with the contact strips ll, while the centre serves for leading away the current.

The contact strips ll and the contacts of the collector may also be easily made exchangeable in order to facilitate their replacement.

In order to guarantee a good contact between collector and regulating winding it is generally expedient to arrange the spindles or shafts S in spring supported bearings. Also with a View of good contact-making. the nuts of the spindles or the guide sleeves of the spindles in the holes of the collector may be arranged resiliently.

The contact strips ii and ll may also be arranged resiliently so that they yield, when the contacts of the collector are pressed aga nst them and may, before interruption occurs, slightly follow the contacts when these recoil.

Fig. 12 shows a special construction of the contact strips H and 5?. These latter have a small strip 222 which is insulated from the main strip This strip 22 is connected with the main strip by means a condenser Z-l having a parallel esistanc-e and serves as prelimin ry contact. The auxiliary strips are resiliently arranged and project a little beyond the main strips 23. During the regulating operation the contacts of the collector first touch the auxiliary strips 272 and then the main strips 23. When a contact is disconnected from the main strip 23 the auxiliary strip 22 still keeps contact for a While. The

switch energy is absorbed by the condenser 24 and clamped out in the resistance.

In Figs. 13, 13a and 13b there is shown a regulating transformer which, as regards the windings and the collector, is like that shown in Figs. 1 to 6, that is to say, a section at the place Where the core I is crossed by conductor It]. In this embodiment the switching is not effected with the aid of contacts arranged on the collector, but by means of a special device. The ends of the conductor Ill are connected with contact segments 26a and 28b. The contact ring 21 consisting of two disconnected halves 21a and 21b is driven by means of the spindles Hill which drive the collector, so that the two elements 21a and 27b of the same make alternate contact with the contact segments. The elements Na and 2111 are connected with the segments 5a, 5b of the two-part collector 5 by means of flexible conductors NH. The movable contact ring 21 is adjusted in such a way, that the elements 21a and 211) only come into contact with the contact segments 26a and 261'), when the parts 5a and 5b of the collector 5, electrically connected to said elements, are in contact with the regulating winding. Then the elements 21a and 21b disengage the contact segments 26a and 26b before the parts of collector 5, corresponding to said elements, are lifted from the regulating winding. The segments EM and 211) therefore, overlap each other.

The contact ring 2'! follows a circular path in a plane P-P and may be driven by threadless parts I02 of the spindles.

Fig. 14 shows a device similar to that just described, likewise for a two-part collector. However, the contacts are connected with the inner ends of the conductors 10, which are led through the core. A ring 30 is provided for the current collection, said ring serving the same purpose and being driven in the same manner as the contact ring 21 of the embodiment shown in Fig. 13. Ring 30 serves as junction point. At that point the operating current is led away. The two enter ends of the connections I are permanently electrically connected with the parts 5a, 5b of the collector. The contacts 8 and the contact strips ll become superfluous.

Fig. shows a device similar to that before described. But it is intended for a four-part collector and is provided with another arrangement of the conductors ID in the core I of the transformer. The designation of parts is the same as that in Fig. 14.

The device shown in Fig. 15 is intended as a Junction point. It replaces the contacts I5 and the contact strips I! of the embodiment shown in Fig. 8, whose contact segments are connected with the segments of the device by means of flexible conductors or other electric connections.

I claim:

1. In a regulating transformer, an iron core, a regulating winding on said core with the turns thereof forming a substantially cylindrical outer surface, a ring-shaped collector of larger diameter than the outer surface of said regulating winding surrounding said winding, a threaded rotatable spindle extending longitudinally of said winding, means for moving said spindle eccentrically during rotation thereof, threads carried by said ring-shaped collector engaging the threads of said spindle whereby the collector is moved eccentrically into engagement with the outer surface of the regulating winding and longitudinally of the winding during rotation of the spindle, insulating means electrically separating parts of said collector ring, circumferentially spaced contact strips adapted to be engaged by parts of said collector ring, means extending through the core connecting said contact strips, and a terminal lead connected to said conducting means within the core.

2. In a regulating transformer, an iron core, a regulating winding on said core with the turns thereof forming a substantially cylindrical outer surface, a ring-shaped collector of larger diameter than the outer surface of said winding surrounding the winding, means for moving'said ringshaped collector longitudinally of said winding and eccentrically into engagement with the turns thereof, insulating means electrically separating parts of said collector ring, circumferentially spaced contact strips arranged to be engaged by parts of said coll ector ring, and. means for suppressing the flux in said core when two parts of said collector ring engage a turn of said regulating winding.

3. In a regulating transformer, an iron core, a regulating winding on said core with the turns thereof forming a substantially cylindrical outer surface, a ring-shaped collector of larger diameter than the outer surface of said winding surrounding the winding, means for moving said ring-shaped collector longitudinally of said winding and eccentrically into engagement with the turns thereof, insulating means electrically separating parts of said collector ring, circumferentially spaced contact strips arranged to be engaged by parts of said collector ring, a conductor extending through said core connecting said contact strips, and a terminal lead connected to said conductor within the core.

4. In a regulating transformer, an iron core, a primary winding on said core, a secondary winding on said core surrounding said primary winding, said secondary winding being formed of turns providing a substantially cylindrical outer surface, a ring-shaped collector of larger diameter than the outer surface of said secondary Winding surrounding the secondary winding, a rotatable spindle extending longitudinally of said windings, threads carried by said spindle of a pitch corresponding to the pitch of the turns of the secondary winding, means for moving said spindle eccentrically during rotation thereof, threads carried by said ring-shaped collector engaging the threads of said spindle whereby the collector is moved eccentrically into engagement with the outer surface of the secondary winding and longitudinally thereof during rotation of the spindle, insulating means electrically separating parts of said collector ring, circumferentially spaced contact strips, contact members carried by said parts of the collector ring for engaging said contact strips during eccentric movement of the collector ring, a terminal lead connected to said contact strips, and means associated with said terminal lead for suppressing flux in said core when two parts of said collector ring engage the secondary winding.

GEORGE LEISCHNER.

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