US1716553A - Transformer - Google Patents
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- US1716553A US1716553A US121536A US12153626A US1716553A US 1716553 A US1716553 A US 1716553A US 121536 A US121536 A US 121536A US 12153626 A US12153626 A US 12153626A US 1716553 A US1716553 A US 1716553A
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- projections
- magnetizable
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F29/00—Variable transformers or inductances not covered by group H01F21/00
- H01F29/08—Variable transformers or inductances not covered by group H01F21/00 with core, coil, winding, or shield movable to offset variation of voltage or phase shift, e.g. induction regulators
- H01F29/10—Variable transformers or inductances not covered by group H01F21/00 with core, coil, winding, or shield movable to offset variation of voltage or phase shift, e.g. induction regulators having movable part of magnetic circuit
Definitions
- My invention relates to magnetizable structures, such as transformers, and it has particular relation to an apparatus of'this char acter for impressing a variable voltage upon a receiving circuit.
- One object of my invention is to provide a device of the character set forth having portions adapted for relative translatoryn'iotion.
- Another object of my invention is to provide a magnetizable structure having a plurality of projections, together with means operable at will to magnetically bridge relatively varying portions of the projections.
- a further object of my invention is to pro: vide an apparatus of this character embodying a main coil and a plurality of other coils extending substantially at right angles to the first coil for severally or jointly embracing a slidable magnetizable'member. Viewed from anotherangle, it is an object of my present invention to provide a'inagnetizable structure having a plurality of partially closed magnetic circuits, together with means operable at will to magnetically close only selected circuits to thereby variably en'- crgize a certain coil.
- Figs. 4 and- 5 are views, respectively in side elevation and in section along line 7 V ofFig. 4, ofthe apparatus shown in the preceding'figures, together with power-operated .means for controlling theslidablemember.
- Figs. 6 and .7 are diagrammatic views illustrating the preferred circuit connections,
- Fig.8 is a diagrammatic v'iew illustratin a modified form of the present invention a? applied to a threc-phasecircuit. .Referringto the drawings, the structure liere shown comprises a mainmagnetiz'able 1926. Serial No. 121,536.
- core or body member 11 having a plurality of projections or legs 11, 11 and 11, with which is associated a slidable magnetizable member or armature 12.
- a main primary coil or winding 13 is wound around the middle leg or projection 11"
- an auxiliary primary coil 15 and a secondary coil 14 are disposed at right angles to the coil 13 near opposite sides thereof, and are adapted to selectively embrace the sli'dable magnetizable member 12.
- the coil 14 develops an electromotive force corresponding to the ratio of its turns to those of the'primary winding 13, and the auxiliary coil'15 is energized only at a very .low value, inasmuch as only a small portion of the armature 12 is included within it. If desired,
- the slidable armature 12 may, of course, be so,
- a plurality of shading coils may be pro-' vided in the lower face of the magnetizable member 12 to: prevent the magnetic attraction between thearmature 12 and the projections of the cor-ell from being reduced to a relatively low value.
- Figs. i and 5 rangement for readily eiiecting a sliding movement of the armature 12, which arrangement will he of particular value in .connec tion with relatively large transformers where tween the strips to thus constitute 'a ballbearing or other anti iriction'bearing for the slidable member 12 and relieve part of the pressure between armaturej2 and core 11.
- a plurality of verticallydisposed helical springs 23 are po- 7 1 sitioned to press upwardly against the lower.
- the magnetizable armature 12 may be direct-ly associated with a bifurcated member 'ing or sleeve 25, which is rotatablv mounted upon suitable pedestalsor standards-2% bearing 25 is suitably secured to a gear wheel portion of member 24.
- arrears 27, which is located between" the pedestals 26 and is adapted to be driven by a pinion 28 that is attachedto-thc'shaft of a driving motor 29,. which may be controlled in any suit-' able manner.
- the hub of gear-wheel 27 is'7 the threaded I internally threaded to engage In this way, by suitable reversal and's peed control of the motor 29, the slidable armature 12 may be actuated to any position that is 7 desire the internally threaded hub of gearwheel'27 acting as a traveling nut to propel the screw-threaded member 24 and thearmature 12 in the desired direction and'to the de- Referring to Fig.
- the structure therein shown comprises a three-phase variable-voltage type of transformer embodying, in gen eral, a 'stator or. outside ring 31 and an internal cylinder or inductor rotor 32, which is 55 suitably supported upon a shaft or axle 30.
- the inner surface of the ring 31' is provided with a pluralityof projections or poles this case, eighteen) which are arranged n- 'sets, respectively numbered 33, 34 and 35,
- the cylinder 01 rotor- 32 is provided with a materially smaller munber of larger projections or segments 36. (in i this case, sin) whichmre thus adaptedto magnetically bridgetwt) or three of the projections of the ring3l in accordance with the;
- Each segment 36 has 7 an angular width equal to the stator pole pitch 20 metrically '310L1I1dj-il16' projections of the stator 31, inorder to provide a perfect mechanical and electrical balance. Circuits for one phase only are shown in the figure for 5 the sake of simplicity and clearness, lt will be noted that the windings on" poles 33 and I 35 are connected in seriesrelation between the phase terminals 37 and 38 of the-power supply-and these windingsrespectively cor- 11o respond, for-one phase, to the primary wind- 7 ing 13 and the secondary winding 1510f the previously illustrated type of transformer.
- the windings on the poles 34 form part of the secondary circuits'of-th'e transformer and are adapted to supply a variable volt- 4 age to the secondary terminals, such as 39 and 40. With the inductor armature in the position shown, the ironf circuit through poles 34,
- a magnetizable structure having a sta tionary portion, a second portion adapted for motion past said stationary portion, and coils respectively embracing said stationary portion and at times said second portion.
- a magnetizable structiire having a plurality of projections, means operable at will to magnetically bridge relatively varying portions of said projections, and stationary coils respectively wound on one of said pro-' jections and adaptedtoembrace said means.
- a magnetizablestructure having a-plurality of alined projections, means for mag netically-bridging variousportions of said projections, and coils respectively Woundon one of said projections and disp'osedsubst-antially parallel thereto for receiving said means' V 4.
- a magnetizable structure having a plurality of alined rojections, slidable magnetizable means or variably bridging said projections, and a plurality of coils for respectively magnetizing said structure and at times embracing said means.
- a magnetizable structure having a'plurality of projections, a magnetizable member for. linking selected numbers of said projections,and a plurality of coils for respectively embracing'various portions of said member.
- a magnetizable structure having a plurality of projections, a magnetizable-member for hnkmg predetermined pairs of said pro-' jections, a coil wound on said structure, and a plurality of other coils for severally or jointly embracing said member.
- a magnetizable structure having a plurality of projections, means for ma netically close-circuiting and open-circuitingselected projections, a coil wound on one of said pro jections, and a plurality of other coils for severally or jointly embracing said member.
- a magnetizable structure having a plurality of alined projections, a slidable ma n'etizable member for linking selected numbers of said projections, and aplurality of coils extending parallel to said projections for respectively embracing various portions of said member.
- a 'magnetizable structure having a-plurality of alined projections, a slidable magnetiz'able member for linking predetermined pairs of said projections, a coil wound on said structure, and a plurality of other coils extending substantially at right angles to the first coilfor severally or jointly embracing said member.
- a magnetizable structure having a plurality of alined projections, a slidable member for magnetically close-circuiting and open-circuiting selected projections, a coil wound on one of said projections, and a plurality of other coils extending at an angle to the first coil for severally or jointly embracingsaid member,
- A- magnetizable structure having a plurality of partially closed magnetic circuits, a plurality of inductively related coils associated therewith, and means operable at will through one of said coils to magnetically close only selected circuits to thereby variably energize said coil.
- a magnetizable structure having a plurality of partially closed magnetic oi cuits, a coil for energizing said circuits, a p urality' of other coils inductively related to the first coil, and magnetizable means operable into one of said othercoils for closing only selected circuits to thereby variably energize 1 that coil.
- a magnetizable structure having a pluralityof partially closed magneticcircuits, a coil for energizing said circuits, a plurality of other coils inductively related to the first coil, and slidable magnetizable means operable through one of said other coils for closing only selected circuits to thereby variably energize that coil.
- a magnetizable structure having a plurality of partially closed magnetic circuits, a coil for energizing said circuits, a plurality of other coils inductively related to the first coil, and ma'gnetizable means operable through said other coils for closing only selected circuits to thereby variably energize of the others being connected in series relation.
- a magnet-izable structure having a plu rality of partially closed magnetic circuits,a
- a magnetizable structure having a P111? rality of partially closed magnetic circuits, a coil for energizing said circuits, a plurality of other coils inductively related to the first rality of alined projections, means for mag'- misses lnetically hridging various portions: of said projections, and means for varying the pres sure of said means upon said projections.
- a magnetizable structure having a plu-- rality of alin'edrprojections, a magnetizable member, means for sliding said member over saidprojections, and spring means for'supporting part of the pressure'of said member.
- a magnetizable structure having aplurality of alined projections, a magnetizable armature, ball bearings interposed between ling screw and nut associated with said armature, a motor geared to said nut, and a .said armature and said projections, a travel plurality of springs for supporting a portion 7 of thepressure of said armature.
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- Power Engineering (AREA)
- Electromagnets (AREA)
Description
Patented June ll, 1929 RAY I. HIGBEE, F E DGEWOOD, PENNSYLVANIA.
TRANSFORMER.
Application filed July 10,
My invention relates to magnetizable structures, such as transformers, and it has particular relation to an apparatus of'this char acter for impressing a variable voltage upon a receiving circuit.
One object of my invention is to provide a device of the character set forth having portions adapted for relative translatoryn'iotion. Another object of my invention is to provide a magnetizable structure having a plurality of projections, together with means operable at will to magnetically bridge relatively varying portions of the projections.
More specifically stated, it is an object of my invention to provide a structure of the class in question having a plurality of al ned projections, together with a slidable magnetizable member for variably bridging or linking selected numbersofsuch projections.
A further object of my invention is to pro: vide an apparatus of this character embodying a main coil and a plurality of other coils extending substantially at right angles to the first coil for severally or jointly embracing a slidable magnetizable'member. Viewed from anotherangle, it is an object of my present invention to provide a'inagnetizable structure having a plurality of partially closed magnetic circuits, together with means operable at will to magnetically close only selected circuits to thereby variably en'- crgize a certain coil.
Other and more specific objects of my invention will become evident fromthe following detailed description, taken in conjunction with the accompanying drawings,- wherein I Figures 1 to 3, inclusive, are views, in elevation, of a transformer structure embodying my present invention, various positions. of the slidable magnetizable member being shown in the respective figures.
Figs. 4 and- 5 are views, respectively in side elevation and in section along line 7 V ofFig. 4, ofthe apparatus shown in the preceding'figures, together with power-operated .means for controlling theslidablemember. Figs. 6 and .7 are diagrammatic views illustrating the preferred circuit connections,
that are employed in-connection with the present invention, and
Fig.8 is a diagrammatic v'iew illustratin a modified form of the present invention a? applied to a threc-phasecircuit. .Referringto the drawings, the structure liere shown comprises a mainmagnetiz'able 1926. Serial No. 121,536.
core or body member 11 having a plurality of projections or legs 11, 11 and 11, with which is associated a slidable magnetizable member or armature 12. A main primary coil or winding 13 is wound around the middle leg or projection 11", while an auxiliary primary coil 15 and a secondary coil 14 are disposed at right angles to the coil 13 near opposite sides thereof, and are adapted to selectively embrace the sli'dable magnetizable member 12. is adapted to be actuated by any suitable means, as generally indicated by the reference character 16, to pass through the coils 14 and 15, while sliding over the projections 11*, 11 and 11 of the main core member 11.
It will be observed that in Fig. .1 the slid able member 12 occupies its right-hand position, whereby the magnetic circuit between the projections 11 and 11 only is closed. In this way the auxiliary coil15 is fully energized in accordance with the voltage ratio between that coil and the main primary coil 13, whereas the secondary coil 14, inasmuch as its magnetic circuit extending between projections 11 and 11 is open circuited, that is to say, since only an air core is provided for the coil 14, substantially no voltage will be induced therein.
As the slidable member 12 is actuated toward-the left to the position shown in Fig. 2, the amount of flux threading the coils ofsecondary winding position shown in Fig. 8, in which the slidable member 12 occupies a left-hand position, the coil 14 develops an electromotive force corresponding to the ratio of its turns to those of the'primary winding 13, and the auxiliary coil'15 is energized only at a very .low value, inasmuch as only a small portion of the armature 12 is included within it. If desired,
the slidable armature 12 may, of course, be so,
far removed from either of the coils 14 and 15 that substantially no volt-ageiis developed therein, whereas either full tial voltage may be developed in :the other coil, depending upon the position of the armature 12 with respect'there'to.
In this way it will be seen that the voltage of secondary creased from a substantially zero value to a value corresponding to the full-ratio of its turns-t0 the turns of the In order to reduce the load current to aminimum value, primary windings 13 and '15 are connected in series re- That is to say, the member 12 14 increases; while, in the voltage or par primary winding 13. .magnetizable or no winding 14 may be gradually inlation, as illustrated in Figs. 6 and in such;
add. 7 Consequently, my transformer Struc-Q nected in circuit without load and, when loadsubstantially. zere to the normal or rated'seca manner that their induced voltages will ture operates with a'relatively small magjnetizing current and power loss when coned, will provide any voltage (l8S1IG(l,- f1()m ondary voltage of the-transformer;
Performance and characteristics of my transformer will compare closely at full volt-' V age with that of a standardtransformer of similardimensions. While thefield of appli- Y cation of such a transformer is relatively reat, it is particularly adapted to the followin uses r 1. it
arting any type of alternating-currentmotor, in which case'it may replace both ill the transformer andthe starter that are usually employed. a a
2. Switching of electric circuits under conditions where arcing and burning is especially undesirable or dangerous, 3; 0pei'ating variable speed alternatin oration and speed changes.
4. Reducing the no-load or magnetizing current motors and providing smooth acce 7 current losses, i
- A plurality of shading coils may be pro-' vided in the lower face of the magnetizable member 12 to: prevent the magnetic attraction between thearmature 12 and the projections of the cor-ell from being reduced to a relatively low value.
Figs. i and 5 rangement for readily eiiecting a sliding movement of the armature 12, which arrangement will he of particular value in .connec tion with relatively large transformers where tween the strips to thus constitute 'a ballbearing or other anti iriction'bearing for the slidable member 12 and relieve part of the pressure between armaturej2 and core 11.
- On either side of the core 11 a plurality of verticallydisposed helical springs 23 are po- 7 1 sitioned to press upwardly against the lower.
.- v strip 21 or its equivalent,thereby further dc:
. traction of the magnetizable armature 12 in accordance with the'scale, the spring members.
- 24, which has a screw-threaded portion that is adapted to extend through a suitable bear creasing the effective pressure or magnetic at-' V or'adjustment, of The magnetizable armature 12 may be direct-ly associated with a bifurcated member 'ing or sleeve 25, which is rotatablv mounted upon suitable pedestalsor standards-2% bearing 25 is suitably secured to a gear wheel portion of member 24.
sired extent.
illustrate a mechanical: ar
The"
33 34* and 35", etc., to correspond to the phases of the circuit. The cylinder 01 rotor- 32 is provided with a materially smaller munber of larger projections or segments 36. (in i this case, sin) whichmre thus adaptedto magnetically bridgetwt) or three of the projections of the ring3l in accordance with the;
position of therotoi Each segment 36 has 7 an angular width equal to the stator pole pitch 20 metrically '310L1I1dj-il16' projections of the stator 31, inorder to provide a perfect mechanical and electrical balance. Circuits for one phase only are shown in the figure for 5 the sake of simplicity and clearness, lt will be noted that the windings on" poles 33 and I 35 are connected in seriesrelation between the phase terminals 37 and 38 of the-power supply-and these windingsrespectively cor- 11o respond, for-one phase, to the primary wind- 7 ing 13 and the secondary winding 1510f the previously illustrated type of transformer.
The windings on the poles 34 form part of the secondary circuits'of-th'e transformer and are adapted to supply a variable volt- 4 age to the secondary terminals, such as 39 and 40. With the inductor armature in the position shown, the ironf circuit through poles 34,
is not closed and the secondary voltage, due
to windings on these poles, will be practically p 'zero.o V a The inductor segments 36 close the iron circuits through each, pair of polesi33 and '35.- Since the windings on each pair 'ofthese poles are connected-iii series relation, in such manner as to add theifvoltages, the Voltage on themain'primary winding will be reduced by the Voltage drop, due to the windings on poles 35. In this way the no-load power 1 I V p v 100 Suitable windings are distributed Q sym- I losses of the transformer may be materially I reduced, as previously explained.
Turning the inductor ,arniature 32 to an angle equal to the pole pitch will transfer the closed iron magnetic circuit from poles 33 and to poles 33 and 34. The voltage consumed in the windings on poles 35 will decrease toa low value since the iron magnetic circuit through these poles is not'now closed. On the other hand, the voltage impressed on the main primary windings on rent or no-load losses.
I do not wish to be restricted to the specific circuit connections or arrangement ofparts herein set. forth, as various modifications thereof may be efiecte'd Witho'ut departing from the spirit and scope of my invention.
-I desire,therefore, that only such limitations shall be imposed as are indicated in .the appended claims. v
I claim as my invention:
1. A magnetizable structure having a sta tionary portion, a second portion adapted for motion past said stationary portion, and coils respectively embracing said stationary portion and at times said second portion.
2. A magnetizable structiire having a plurality of projections, means operable at will to magnetically bridge relatively varying portions of said projections, and stationary coils respectively wound on one of said pro-' jections and adaptedtoembrace said means. 3. A magnetizablestructure having a-plurality of alined projections, means for mag netically-bridging variousportions of said projections, and coils respectively Woundon one of said projections and disp'osedsubst-antially parallel thereto for receiving said means' V 4. A magnetizable structure having a plurality of alined rojections, slidable magnetizable means or variably bridging said projections, and a plurality of coils for respectively magnetizing said structure and at times embracing said means.
5. A magnetizable structure having a'plurality of projections, a magnetizable member for. linking selected numbers of said projections,and a plurality of coils for respectively embracing'various portions of said member.
6. A magnetizable structure having a plurality of projections, a magnetizable-member for hnkmg predetermined pairs of said pro-' jections, a coil wound on said structure, and a plurality of other coils for severally or jointly embracing said member.
7 A magnetizable structure having a plurality of projections, means for ma netically close-circuiting and open-circuitingselected projections, a coil wound on one of said pro jections, and a plurality of other coils for severally or jointly embracing said member.
8. A magnetizable structure having a plurality of alined projections, a slidable ma n'etizable member for linking selected numbers of said projections, and aplurality of coils extending parallel to said projections for respectively embracing various portions of said member. v
9. A 'magnetizable structure having a-plurality of alined projections, a slidable magnetiz'able member for linking predetermined pairs of said projections, a coil wound on said structure, and a plurality of other coils extending substantially at right angles to the first coilfor severally or jointly embracing said member.
10. A magnetizable structure having a plurality of alined projections, a slidable member for magnetically close-circuiting and open-circuiting selected projections, a coil wound on one of said projections, and a plurality of other coils extending at an angle to the first coil for severally or jointly embracingsaid member,
' 11. A- magnetizable structure having a plurality of partially closed magnetic circuits, a plurality of inductively related coils associated therewith, and means operable at will through one of said coils to magnetically close only selected circuits to thereby variably energize said coil.
' 12. A magnetizable structure having a plurality of partially closed magnetic oi cuits, a coil for energizing said circuits, a p urality' of other coils inductively related to the first coil, and magnetizable means operable into one of said othercoils for closing only selected circuits to thereby variably energize 1 that coil.
13. A magnetizable structure having a pluralityof partially closed magneticcircuits, a coil for energizing said circuits, a plurality of other coils inductively related to the first coil, and slidable magnetizable means operable through one of said other coils for closing only selected circuits to thereby variably energize that coil.
14. A magnetizable structure having a plurality of partially closed magnetic circuits, a coil for energizing said circuits, a plurality of other coils inductively related to the first coil, and ma'gnetizable means operable through said other coils for closing only selected circuits to thereby variably energize of the others being connected in series relation.
One of said other coils, the first coil and one i 7 15. A magnet-izable structure having a plu rality of partially closed magnetic circuits,a
coil for energizing said circuits, a plurality of other coils inductively related to the first coil, and magnetizable means for closing only selected circuits to thereby variably energize one of said other coils, the first coil and one of the others being conductively connected in cumulative voltage relation. I a
16 A magnetizable structure having a P111? rality of partially closed magnetic circuits, a coil for energizing said circuits, a plurality of other coils inductively related to the first rality of alined projections, means for mag'- misses lnetically hridging various portions: of said projections, and means for varying the pres sure of said means upon said projections.
18. A magnetizable structure having a plu-- rality of alin'edrprojections, a magnetizable member, means for sliding said member over saidprojections, and spring means for'supporting part of the pressure'of said member.
19. A magnetizable structure having aplurality of alined projections, a magnetizable armature, ball bearings interposed between ling screw and nut associated with said armature, a motor geared to said nut, and a .said armature and said projections, a travel plurality of springs for supporting a portion 7 of thepressure of said armature.
In, testimony whereof, Ihave hereunto subscribed my 1926.
RAY P. Brenna.-
name this. 9th day of July
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US121536A US1716553A (en) | 1926-07-10 | 1926-07-10 | Transformer |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US121536A US1716553A (en) | 1926-07-10 | 1926-07-10 | Transformer |
Publications (1)
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US1716553A true US1716553A (en) | 1929-06-11 |
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US121536A Expired - Lifetime US1716553A (en) | 1926-07-10 | 1926-07-10 | Transformer |
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Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2442751A (en) * | 1946-06-05 | 1948-06-08 | Jerome G Abbott | Variable transformer |
US2484421A (en) * | 1945-07-12 | 1949-10-11 | Mark T Moore | Electric arc welding apparatus |
US2514908A (en) * | 1948-09-30 | 1950-07-11 | Lee E Stilphen | Voltage regulator |
US2609531A (en) * | 1947-12-03 | 1952-09-02 | Karl F Kirchner | Inductance device |
US2930010A (en) * | 1956-09-13 | 1960-03-22 | American Radiator & Standard | Dynamo transformer |
US3028754A (en) * | 1958-11-10 | 1962-04-10 | Ametek Inc | Measuring instrument |
US3176241A (en) * | 1961-04-07 | 1965-03-30 | Jimmie S Hogan | Magnetic switching device |
US3517362A (en) * | 1968-09-11 | 1970-06-23 | John A Mead | Differential transformer flux valve |
US5329268A (en) * | 1992-10-09 | 1994-07-12 | Mcqueen Clarence W | Transformer variable power |
US20090058584A1 (en) * | 2007-08-29 | 2009-03-05 | Siemens Energy & Automation, Inc. | Three-phase multi-winding device |
US9728318B2 (en) * | 2012-06-08 | 2017-08-08 | Pontificia Universidad Catolica Del Peru | Drum-type tri-phase transformer and methods for producing same |
-
1926
- 1926-07-10 US US121536A patent/US1716553A/en not_active Expired - Lifetime
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2484421A (en) * | 1945-07-12 | 1949-10-11 | Mark T Moore | Electric arc welding apparatus |
US2442751A (en) * | 1946-06-05 | 1948-06-08 | Jerome G Abbott | Variable transformer |
US2609531A (en) * | 1947-12-03 | 1952-09-02 | Karl F Kirchner | Inductance device |
US2514908A (en) * | 1948-09-30 | 1950-07-11 | Lee E Stilphen | Voltage regulator |
US2930010A (en) * | 1956-09-13 | 1960-03-22 | American Radiator & Standard | Dynamo transformer |
US3028754A (en) * | 1958-11-10 | 1962-04-10 | Ametek Inc | Measuring instrument |
US3176241A (en) * | 1961-04-07 | 1965-03-30 | Jimmie S Hogan | Magnetic switching device |
US3517362A (en) * | 1968-09-11 | 1970-06-23 | John A Mead | Differential transformer flux valve |
US5329268A (en) * | 1992-10-09 | 1994-07-12 | Mcqueen Clarence W | Transformer variable power |
US20090058584A1 (en) * | 2007-08-29 | 2009-03-05 | Siemens Energy & Automation, Inc. | Three-phase multi-winding device |
US7948340B2 (en) * | 2007-08-29 | 2011-05-24 | Siemens Industry, Inc. | Three-phase multi-winding device |
US9728318B2 (en) * | 2012-06-08 | 2017-08-08 | Pontificia Universidad Catolica Del Peru | Drum-type tri-phase transformer and methods for producing same |
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