US3691496A

US3691496A - Helitran winding for electrical inductive apparatus

Info

Publication number: US3691496A
Application number: US135712A
Authority: US
Inventors: Nicholas G Beavo
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1971-04-20
Filing date: 1971-04-20
Publication date: 1972-09-12
Anticipated expiration: 1989-09-12
Also published as: FR2150667A1; JPS522087B1

Abstract

This invention relates to electrical inductive apparatus comprising tapped helitran windings. A plurality of separate conductors are simultaneously wound to form the helitran winding. One group of conductors provides a path for the load current of the winding. Another group of conductors has tap leads attached to the conductors. This group is used as a tapped winding for connection to tap changing apparatus. By winding the load and tapped windings simultaneously, the electrical and mechanical properties of tapped helitran windings may be economically improved.

Description

United States Patent Beavo 1 Sept. 12, 1972 [S4] HELITRAN WINDING FOR ELECTRICAL INDUCTIVE APPARATUS [72] Inventor: Nicholas G. Beavo, Sharon, Pa.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

22 Filed: April 20,1971

211 Appl.No.: 135,712

[52] US. Cl. ..336/l50, 323/435, 336/187 [51] Int. Cl. ..I-l0lt 21/12 [58] Field of Search ..336/l50, 69, 70, 186, 187; 323/435 [56] References Cited UNITED STATES PATENTS 2,770,767 11/1956 Nelson ..336/150 X 3,113,281 12/1963 Ayers ..336/150 2,840,790 6/1958 Vogel et a]. ..336/1 50 FOREIGN PATENTS OR APPLICATIONS 1,011,375 11/1965 Great Britain ..336/l50 Primary Examiner-Thomas J. Kozma Attorney-A. T. Stratton and F. E. Browder [5 7] ABSTRACT This invention relates to electrical inductive apparatus comprising tapped helitran windings. A plurality of separate conductors are simultaneously wound to form the helitran winding. One group of conductors provides a path for the load current of the winding. Another group of conductors has tap leads attached to the conductors. This group is used as a tapped winding for connection to tap changing apparatus. By winding the load and tapped windings simultaneously, the electrical and mechanical properties of tapped helitran windings may be economically improved.

9 Claims, 5 Drawing Figures BACKGROUND'OF THE INVENTION 1. Field of The Invention This invention relates in general to electrical inductive apparatus, such as transformers, and more particularly to tapped helitran windings for power transformers.

2. Description Of The Prior Art Helitran windings are particularly suited for high current applications since they can withstand the high circuit stresses which may be encountered in high current service. High current helitran windings have not provided tapping possibilities in the past as often as other types of windings because of the problem associated with diverting the high current during a tap change. The higher current and power levels now being used in the electrical power industry is increasing the need for tapping high current windings. Although used for other applications, most tapped windings are associated with other apparatus to regulate the output voltage or phase angle.

Since present tap changing apparatus is not suitable for tapping high current windings, a separate tapped winding must be used to provide the tap positions. Arrangements known in the prior art to tap high current helitran windings have been costly and exhibit inferior performance. One arrangement consists of positioning a tapped winding around the magnetic core to provide the voltage taps. A helitran winding must be wound around the tapped winding to carry the load current. Usually, a primary winding is disposed around the helitran and tapped windings. This three winding arrangement requires a separate winding tube for the tapped winding. The physical size of the apparatus must be sufficient to enclose the three windings.

Another arrangement to provide a tapped high current helitran winding consists of using a separate transformer. One winding of the separate transformer is connected to the helitran winding. The other winding of the separate transformer is tapped to provide the necessary taps. This arrangement requires the extra cost and space of a separate transformer.

- It is, therefore, desirable to provide a tapped helitran winding in which the tapped portion of the winding can be inductively, physically and economically combined with the load portion of the helitran winding.

SUMMARY OF THE INVENTION This invention discloses a new and improved arrangement for tapping a helitran winding. The helitran winding comprises two windings, a load winding and a tapped winding. Both are wound simultaneously and the number of conductors comprising each winding is dependent upon the current which they may conduct. A sufficient number of conductors are wound to form the load winding. An additional number of conductors, sufficient to conduct the tap-to-tap currents, are wound with the load conductors. The result is a spirally disposed winding structure having a plurality of conductors forming the spiral, some of which conduct the load current and some of which conduct the tap-to-tap currents. The tapped winding includes leads which are connected at intervals throughout the tapped winding to furnish the tap connections from the winding. The

conductors forming the tapped winding are transposed as a solid conductor to equalize radial conductor spacmg.

Winding a tapped helitran winding as taught by this invention eliminates most of the labor involved in winding a separate tapped winding. Winding the load and tapped windings simultaneously also substantially decreases the physical size of the winding structure and improves the mechanical strength of the tapped helitran winding assembly.

BRIEF DESCRIPTION OF THE DRAWING Further advantages and uses of the invention will become more apparent when considered in view of the following detailed description and drawing, in which:

FIG. 1 is a sectional elevational view of a one section helitran winding constructed according to this invention;

FIG. 2 is a sectional elevational view of a two section helitran winding constructed according to this invention;

FIG. 3 is a partial elevational view of the one section helitran winding of FIG. 1 illustrating the method of transposing the conductors;

FIG. 4 is a partial elevational view of the two section helitran winding of FIG. 2 illustrating the method of transposing the conductors; and

FIG. 5 is a schematic circuit diagram of an underload tap changing regulator apparatus using a tapped helitran winding constructed according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Throughout the following description, similar reference characters refer to similar members in all figures of the drawing.

Referring now to the drawing, and FIG. 1 in particular, there is shown a section of an electrical inductive structure which utilizes the teachings of this invention. The structure may be part of a single phase electrical inductive apparatus or it may be one leg of a multiple phase electrical inductive apparatus.

The laminated magnetic core 10 is surrounded by an insulating material 12 onto which the helitran winding 14 is wound. The magnetic core 10 may comprise a plurality of laminations arranged to provide a substantially circular or cruciform cross-sectional shape. The insulating material 12 may be formed by the insulated winding tube on which the helitran winding is wound, by the vertical spacing members between the winding tube and the helitran winding and/or the liquid dielectric which may surround the structure.

The helitran winding 14 is spirally wound onto the insulating material 12. The number of conductors comprising the helitran winding is dependent upon the class, type and rating of the inductive apparatus. The winding section illustrated in FIG. l-shows eight conductors comprising the helitran winding, although other numbers of conductors may be used.

The helitran winding 14 is shown as a one section helitran. The eight conductors comprising the winding are radially disposed in relation to each other and are wound to form a single section during the winding process. That is, the eight conductors forming the section A are all wound at the same time upon the insulating material 12, and the section B is formed by the same eight conductors after one revolution of the winding. Similarly, sections C, D, E and F are formed by successive revolutions of the winding. Transpositions of the conductors are discussed later.

Each conductor of the helitran winding comprisesa conducting material disposed within an insulating material. Therefore, each of the eight conductors shown are insulated from each other throughout the winding. Since eight conductors are used in constructing the helitran winding in FIG. 1, each conductor is common to all sections. The conductor numbers shown illustrate the position of the conductors in different sections.

A primary winding 16 is disposed around the helitran winding 14. The primary winding 16 may be wound in any of the various patterns, such as helitran, continuous wound disks, I-Iisercap and others. An insulating material 18 separates the primary winding 16 from the helitran winding 14 and other parts of the electrical inductive apparatus. The primary conductors 20 of the primary winding 16 are connected to leads, such as the lead 22, which provide means for connecting the primary winding to an external circuit. Similarly, the conductors 1 through 8 of the helitran winding are brought out from the winding for connection to an external circuit.

The helitran winding 14 comprises two groups of conductors which serve two separate functions. One group, the load conductors, form the load winding and are connected to carry the load current supplied by the helitran winding to an external circuit. Another group, the tapped conductors, form the tapped winding and are connected to an external circuit to provide a means for tapping the voltage of the helitran winding 14. The tapped winding carries only the current required by the external circuit connected thereto, such as a tap changin g circuit.

The number of conductors in each of the two groups must be sufficient to safely carry the current which may flow through that group. Although other combinations may be used, the helitran winding 14 shown in FIG. 1 has six load conductors l, 2, 3, 4, 7 and 8, and two tapped conductors, 5 and 6. This arrangement would be used where the load to tapped winding current ratio is approximately 3 1. Although shown asconductors 5 and 6, any two conductors could be used to form the tapped winding. The placement of the conductors in the first section of the winding is not critical; however, when more than one conductor is used for the tapped winding, they should be adjacent to one another within the same winding section to make transpositions easier. The tap leads 22 furnish means for connecting the tapped winding comprising the

conductors

5 and 6 to an external circuit. The leads 22 are schematically shown connected to the

conductors

5 and 6 in sections B, D and F.

FIG. 2 shows a partial view of a multiple section helitran winding wound according to the teachings of this invention. The winding which is shown and which will be described is a two section winding; however, this invention is applicable to helitran windings with more than two sections. The helitran winding 24 is wound on the insulating material 12 which is similar to the insulating material described concerning the structure of FIG. 1. Similarly, the primary winding 26 comprises conductors 20 and insulation 18 as described concerning the winding 16 in FIG. 1.

The two section helitran winding 24 of FIG. 2 is wound with eight insulated conductors. The

conductors

3, 4, 5, 6, 7 and 8 form the load winding and the conductors l and 2 form the tapped winding. Two sections are wound in one revolution of the winding during the winding operation. Thus, the ten sections shown are wound in five revolutions of the winding. The dual sections are denoted by the letters A, B, C, D and E. Tap leads 28 are connected to the tapped winding conductors at the Sections B and D.

In the one section helitran of FIG. 1 and the two section helitran of FIG. 2, the conductors are transposed at intervals throughout the winding. Following the numbers from one section to another indicates how the transpositions are made. Although other transposition intervals may be used, transpositions occur in the helitran windings of both FIGS. 1 and 2 during each revolution of the winding. The transpositions are made at a position in the winding which is between the point where the sectional views of FIGS. 1 and 2 are taken. For example, the transposition of the conductor 8 from the finish turn in section A of FIG. I to the start turn in section B is made at a position in the winding between sections A and B.

FIG. 3 illustrates the transpositions between the winding sections of FIG. 1. The section line I-l indicates the plane at which the sectional view of FIG. 1 was drawn. The conductor 8 is bent vertically downward at position 30, radially inward at position 32 and vertically upward at position 34. The result is that the conductor 8 is transposed from a finish turn to a start turn. The conductor 7 is similarly transposed one winding revolution later. The tapped winding

conductors

5 and 6 are transposed as if they were a single conductor. This would also be true if more than two conductors are being used to form the tapped winding. As a result of this method of transposing, the relative radial position of the tapped conductors is reversed. This permits each conductor of the tapped winding to occupy the same average radial spacing throughout the winding and maintains equal reactance for each conductor.

FIG. 4 illustrates the transpositions between the sections of FIG. 2. The section line Il-Il indicates the plane at which the sectional view of FIG. 2 was drawn. The conductor 4 is moved from the finish turn of the winding layer 36 to the finish turn of the winding layer 38. At the same position in the winding, the conductor 5 is moved from the start turn of the winding layer 38 to the start turn of the winding layer 36. Similarly,

conductors

3 and 6 are transposed one winding revolution later. Although not shown in FIG. 4, the tapped winding conductors l and 2 are transposed as if they were a single conductor. To prevent unequal conductors in the winding layers when more than one conductor is used for the tapped winding, an equal number of lead winding conductors must be transposed when the tapped winding conductors are transposed. Therefore, the

load conductors

7 and 8 are transposed together when the tapped conductors l and 2 are transposed, as shown in FIG. 2.

This invention discloses a new and improved means for tapping the helitran winding of electrical inductive apparatus. FIG. 5 illustrates schematically an application of this invention to a voltage regulating apparatus using a tapped winding. The transformer 40 comprises a magnetic core 42, a primary winding 44, a helitran load winding 46 and a helitran tapped winding 48. The primary winding 44 includes the

terminals

50 and 52 to which may be applied a source of AC potential. The load winding 46 includes the

terminals

54 and 56 and the tapped winding includes the

terminals

58 and 60 and intermediate tapped terminals 62. Although it is not necessary for the proper functioning of the regulator, the

terminals

54 and 58, and the

terminals

56 and 60, are electrically connected together to reduce static and dynamic voltages between the load and tapped windings.

A series transformer 64 comprises a magnetic core 66, a load winding 68 and a regulator winding 70. The series transformer may either aid or oppose the voltage developed by the load winding 46, thus the output voltage developed by the load winding 46, thus the output voltage at the

terminals

72 and 74 is dependent upon the phase and amplitude of the voltage induced in the load winding 68. This is determined by the polarity reversing switch 74 and the tap position selected by the preventative auto tap changing means 76. By utilizing the teachings of this invention, the tap changing regulator may be economically constructed with smaller dimensions and improved durability.

l claim as my invention:

1. A tapped helitran winding structure for electrical inductive apparatus comprising a plurality of radially disposed, spirally wound conductors which form a plurality of winding sections, a tapped winding comprising at least one of said conductors, a load winding comprising the conductors which do not comprise said tapped winding, said tapped winding occupying different radial positions throughout said tapped helitran winding structure, said load winding conducting the load current of said tapped helitran winding structure, said tapped winding having leads connected thereto at intermediate tap positions within said tapped winding, and said tapped winding conducting the tap-to-tap currents of said tapped helitran winding structure.

2. The tapped helitran winding structure of claim 1 wherein the tapped winding comprises a plurality of conductors, said conductors being radially adjacent in each winding section.

3. The tapped helitran winding structure of claim 2 wherein the radially adjacent tapped winding conductors are transposed as a single conductor.

4. A multiple section tapped helitran winding structure for electrical inductive apparatus comprising a plurality of radially and vertically disposed, spirally wound conductors which form a plurality of winding sections, a tapped winding comprising at least one of said conductors, a load winding comprising the conductors which do not comprise said tapped winding, said tapped winding occupying different radial positions throughout said tapped helitran winding structure, said load winding conducting the load current of said tapped helitran winding structure, said tapped winding having leads connected thereto at intermediate ta sit'on within said ta ed windin and said tagp winding conducting tl i tap-to-tap currents of said tapped helitran winding structure.

5. The multiple section tapped helitran winding structure of claim 4 wherein the tapped winding comprises a plurality of conductors, said conductors being radially adjacent in a winding section.

6. The multiple section tapped helitran winding structure of claim 4 wherein the radially adjacent tapped winding conductors are transposed as a single conductor.

7. Load tap changing regulator apparatus comprising a power transformer, a series transformer, tap changing means, said power transformer having a primary winding, a magnetic core, a tapped helitran winding structure, said tapped helitran winding structure comprising a load winding which conducts the load current, a tapped winding to which leads are connected at intermediate tap intervals within said tapped winding, said tapped winding conducting the tap-to-tap currents of said tapped helitran winding structure, said tapped winding occupying different radial positions throughout said tapped helitran winding structure, said load and tapped windings being wound in the same conductor spiral, said series transformer having a first winding connected in series with the load winding of said helitran winding, and said series transformer having a second winding connected to said tap changing means so that the second winding of said series transformer is energized by a voltage dependent upon the tap position selected by said tap changing means.

8. The tapped helitran winding structure of claim 1 wherein the tapped winding progresses radially through adjacent winding sections when said load winding is transposed.

9. The multiple section tapped helitran winding structure of claim 4 wherein the tapped winding progresses radially through adjacent winding sections during a first transposition of said load winding, and the tapped winding progresses axially through winding sections during a second transposition of said load winding.

UNITED STATES PATENT OFFICE CERTIFICATE UF QRREQTION Patent No. 3 69l. l96 bated Seotember 1-2, 1972 In vent or (s) Nicholas G. Blavos It is certified that: error appears in the above-identified paten't v and that 'said Letters Patent are hereby corrected as shown below:

Name of Inventor: Nicholas G. B lavos Signed and sealed" 29th; day of May 1973.;

' (SEAL) Attest:

EDWARD M .FLET( IHER,JR. ROBERT GOTT SCHALK Attestlng Off1 cer Commissioner of Patents ORM PO-1050 (10-69) uscoMM-oc dean-Pee i U. S. GOVIINIIIIT RIIIITIIG OPIICI I". Ol $l-S84 I TED STATES PATENT @FFKQE v 1 w}? QfifiEEQE Patent N0- 3.69l. l96 bate September 1-2 1972 In ventofls) Ni'chola's'G. Blavos It is certified that error appears in the above-identified patent I and that said Letters Patent are hereby corrected as shown below:

Name of Inventor: Nicholas G. Blavos Signed and sealed 291th, day 0;? May 1973.,

' (SEAL) Attest:

EDWARD.M.FLETCHER,JR. ROBERT GOTTSCHALK Attestlng Officer Commissioner of Patents FORM PO-1050 (10-69) uscoMM-oc dean-P09 U. 5. GOVERNMENT PRINTING OFFICE I") 0-l6l-334

Claims

4. A multiple section tapped helitran winding structure for electrical inductive apparatus comprising a plurality of radially and vertically disposed, spirally wound conductors which form a plurality of winding sections, a tapped winding comprising at least one of said conductors, a load winding comprising the conductors which do not comprise said tapped winding, said tapped winding occupying different radial positions throughout said tapped helitran winding structure, said load winding conducting the load current of said tapped helitran winding structure, said tapped winding having leads connected thereto at intermediate tap positions within said tapped winding, and said tapped winding conducting the tap-to-tap currents of said tapped helitran winding structure.