US3820238A

US3820238A - Method of constructing electrical apparatus

Info

Publication number: US3820238A
Application number: US00361088A
Authority: US
Inventors: W Caputo; C Mullis
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1973-05-17
Filing date: 1973-05-17
Publication date: 1974-06-28
Anticipated expiration: 1991-06-28
Also published as: JPS5018970A; CA973695A

Abstract

A METHOD OF CONSTRUCTING ELECTRICAL APPARATUS HAVING A GAPPED MAGNETIC CORE STRUCTURE COMPRISING UPPER AND LOWER YOKE PORTIONS, FIRST AND SECOND OUTER LEG MEMBERS, AND A GAPPED INNER WINDING LEG, USING SIMILARLY DIMENSIONED FSHAPED LAMINATIONS. FOUR F-SHAPED LAMINATIONS, TWO OF WHICH ARE REVERSED, ARE ASSEMBLED TO PROVIDE A BASIC GROUP OF LAMINATIONS, AND A PLURALITY OF BASIC GROUPS ARE SUPERPOSED TO PROVIDE A PRELIMINARY RECTANGULAR STRUCTURE OF FRAME IN WHICH THE LENGTH OF THE OUTER LEGS IS ALMOST TWICE THEIR DIMENSION IN THE FINAL CORE STRUCTURE, WHICH PROVIDES AN INNER LEG HAVING A GAP THEREIN SUFFICIENT TO RECEIVE AN ASSOCIATED ELECTRICAL WINDING. THE PRELIMINARY STRUCTURE IS THEN COMPRESSED TO ITS FINAL DIMENSIONS TO CAUSE THE INNER WINDING LEG PORTIONS TO ADVANCE INTO THE ELECTRICAL WINDING AND PROVIDE A NON-MAGNETIC GAP THEREIN.

Description

United States Patent 1191 Caputo et al.

[ June 28, 1974 METHOD OF CONSTRUCTING Primary Examiner-Charles W. Lanham ELECTRICAL APPARATUS Assistant Eraminer-Carl E. Hall [75] Inventors: William R. Caputo, Wycoff; Clyde Attorney Agent or firm-D Lackey M. Mullls, Glen Rock, both of NJ. [57] ABSTRACT Assigns-e1 Westinghouse Electric Corporation, A method of constructing electrical apparatus having Plttsburgh, a gapped magnetic core structure comprising upper [22] Filed; May 17 1973 and lower yoke portions, first and second outer leg members, and a gapped inner winding leg, using simi- 7 1 PP 361,088 larly d1mens1oned F-shaped laminatlons. Four F- shaped laminations, two of which are reversed, are as- 52 us. 01 29/606, 29/609 336/165 sembled to Provide a basic group of laminations and 8 33 /17 336/217 336/234 hour/W0 plurality Of basic groups are superposed to provide a 5 Fi f Search n 29/ 0 09- 33 /134 1 5 preliminary rectangular structure Of frame in which 336/178 212 217 the length of the outer legs is almost twice their dimension in the final core structure, which provides an [56] References Cited inner leg having a gap therein sufficient to receive an associated electrical winding. The preliminary struc- UNITED STATES PATENTS ture is then compressed to its final dimensions to 1,726,100 8/1929 Daqosta 29/606 X cause the inner winding leg portions to advance i 29/609 UX the electrical winding and provide a non-magnetic gap 355,689 lI/l967 Paddison er al. 336/234 therem' 9 Claims, 6 Drawing Figures I O O O O O 56 o o ./54 0 O O Q n 6 68\- T O O 64 .188 o 2 a O O O O O METHOD OF CONSTRUCTING ELECTRICAL APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates in general to electrical inductive apparatus, and more specifically to electrical inductive apparatus having a gapped magnetic core structure, such as an electrical reactor.

2. Description of the Prior Art Certain types of electrical inductive apparatus, such as iron core reactors, utilize a magnetic core structure having one or more non-magnetic gaps in the magnetic circuit to provide predetermined electrical characteristics. The gapped magnetic core structure produces sound levels which may be objectionable in certain applications. In a specific application for an air cooled iron core reactor, magnetic cores were constructed using both the C and E-I core configurations. Both core arrangements produced a sound level of approximately 90 db well above the maximum acceptable 70 db level (at 4 feet) for this specific application. The mating faces of the Come, and the mating faces of the E-I core were ground and cemented together with an epoxy resin. This lowered their sound levels to an acceptable magnitude. Shipment of the reactors, however, deleteriously affected the flatness of the mating faces and the reactors had to be disassembled and their mating faces reground in order to again provide an acceptable sound level.

Gapped magnetic core assemblies may be formed by stacking flat F-shaped laminations, such as disclosed in U.S. Pat. No. 3,355,689. This arrangement eliminates the grinding and cementing operations, since there are no mating faces, and this arrangement is thus preferable to the C and BI arrangements. Thus, it would be desirable to provide a new and improved method of constructing gapped electrical inductive apparatus using F-shaped laminations, which method facilitates the assembly of the apparatus while achieving a sound level of 70 db. or less.

SUMMARY OF THE INVENTION Briefly, the present invention is a new and improved method of constructing electrical inductive apparatus having a gapped magnetic core structure. The major non-magnetic gap of the apparatus is disposed within the associated winding such that it is located at substantially the midpoint thereof, which location is preferable when the reactor is used as part of a filter network for reducing the ripple magnitude of the A-C component in direct current. This location of the gap, however, does not adversely affect the sound level of the apparatus, nor does it complicate the manufacture of the apparatus, due to a new and improved method of constructing the apparatus.

More specifically, the magnetic core is constructed of similarly shaped and dimensioned, flat, F-shaped metallic, magnetic laminations, with the dimensions of the back portion and projecting portions of the laminations and the dimensions of the associated winding, all being selected to enable a preliminary rectangular structure or frame having two yoke portions, two outer leg portions, and an intermediate or winding leg to be built up which enables the laminations which make up each of the two portions of the gapped winding leg to be rigidly clamped together before they are disposed within the winding. The yoke portions of this preliminary structure are spaced far enough apart to enableand the yoke portions are moved towards one another to advance the ends of the winding leg portions into the opening of the winding to establish the desired non magnetic gap therein. The laminations are dimensioned such that when the desired gap in the winding leg is established, the ends of the laminations which make up the outer leg members are spaced from the back portions of the other F-shaped lamination in the same layer, to insure that there are no mating faces to produce-noise when the apparatus is energized.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be better understood, and further advantages and uses thereof more readily apparent, when considered in view of the following detailed description of exemplary embodiments, taken with the accompanying drawings, in which:

FIG. 1 is a perspective view of electrical inductive apparatus which may be constructed according to the teachings of the invention; and

FIGS. 2 through 6 illustrate the steps of constructing the electrical inductive apparatus shown in FIG. 1, according to the teachings of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, and FIG. 1 in particular, there is shown electrical inductive apparatus 10, such as an electrical reactor, having an electrical winding 12, shown in phantom, disposed in inductive relation with a magnetic core 14. Magnetic core 14 includes a plurality of layers 15 of metallic laminations assembled to provide first and

second yoke portions

16 and 18, respectively, first and second

outer leg portions

20 and 22, respectively, which extend between the spaced first and second yoke portions 16v and 18, and an intermediate or winding leg member 24 which has a non-magnetic gap 26 therein. The winding is disposed about the winding leg 24, with winding leg 24 having a first portion 28 extending outwardly from yoke 16, and a second portion 30 extending outwardly from yoke 18. The first and

second portions

28 and 30, respectively, of the winding leg are aligned with one another.

A plurality of

lock plate members

32, 34, 36, 38, 40 and 42 are disposed against the flat major surfaces on one side of the magnetic core 14, and similar lock plate members are disposed on the other side thereof. Nut and bolt combinations, such as nut and bolt combination 44, are disposed to clamp the laminations rigidly together, perpendicular to their fiat major surfaces. The bolts are disposed through aligned openings in the face plates and laminations, which openings have insulating sleeve members disposed therein to prevent the bolt from shorting adjacent laminations. Insulating washers are also used to prevent shorted turns. Mounting feet (not shown) may be bolted to the lower yoke portion 18.

Electrical apparatus may be advantageously constructed according to the teachings of the invention, with the steps of the new and improved method being shown in FIGS. 2 through 6.

More specifically, as illustrated in FIG. 2, the first step of the invention is to provide a first F-shaped lamination 50 formed from magnetic material, such as silicon steel, having a thickness dictated by the specific application. Lamination 50 has a back portion 52, and first and second projecting

portions

54 and 56, respectively, which project outwardly from a common edge of the back portion. The first projecting portion 54 is located at one end of the back portion 52, forming an outer corner 58 at their intersection. The second projecting portion 56 is disposed to extend outwardly from substantially the midpoint of the back portion 52, represented by center line 60. Since the second projeeting portion 56 will function as the winding leg, it will carry twice the magnetic flux as the yoke and outer leg portions and thus the width dimension of the second projecting portion 56 is preferably twice the width W of the yoke and outer leg portions. The back portion 52 and first and second projecting

portions

54 and 56 each have a plurality of openings disposed therein, perpendicular to their major opposed surfaces, such as opening 62, for aligning and clamping superposed laminations with clamping means, such as the nut and bolt combination 44 shown in FIG. 1.

The next step of the method, illustrated in FIG. 3, is to provide a second F-shaped lamination 64, which is similar in configuration and dimensions to lamination 50. Lamination 64 includes a back portion 66, first and second projecting

portions

68 and 70, respectively, and an outer corner 72 formed by the intersecting back and first projecting portions. The second F-shaped lamination 64 is disposed in the same plane as the first F- shaped lamination, with the outwardly extending ends of. their second projecting

portions

56 and 70 facing one another and aligned with one another, as indicated by dotted lines 74. The facing ends of the second projecting

portions

56 and 70 are spaced apart by a dimension indicated by a line 76, which-exceeds the dimension of the associated electrical winding 12 between the ends of the winding which have the openings therein for receiving the winding leg of the magnetic core. The winding, and first and second projecting portions, are all dimensioned such that when the second projecting

portions

56 and 70 are spaced by a dimension 76 sufficient to receive the winding 12, that the ends of the first projecting portions extend past one another by a dimension 78. The magnitude of dimension 78 is not critical, it only being important that they overlap. It will be noted that both the first and second F-shaped laminations are oriented with similar sides thereof facing upwardly, such that corner 58 provides the upper righthand corner and comer 72 provides the lower left-hand corner, of a preliminary structure or frame which is completed in FIG. 3 by

dotted lines

80 and 82.

The next step, shown in FIG. 4, is to provide a third F-shaped lamination 84, similar in configuration and dimensions to the first and second F-

shaped laminations

50 and 64, except that it is turned over or inverted. Lamination 84 has a back portion 86, first and second projecting

portions

88 and 90, and an outer corner 92 formed by the intersection of the back and first projecting

portions

86 and 88. Lamination 84 is stacked such that its outer comer 92 forms the lower right-hand comer of the preliminary structure, with its back portion 86 superposed over the back portion 66 of lamination 64, its second projecting portion superposed over the second projecting portion 70 of lamination 64, and its first projecting portion extending towards and overlapping the end of the first projecting portion of lamination 50 by the dimension 78.

The next step, shown in FIG. 5, is to provide a fourth F-shaped lamination 94 similar in configuration and dimensions to the first, second and third F -shaped laminations, and inverted, relative to the orientation of the first and second F-shaped laminations, similar to the third F-shaped lamination 84. Lamination 94 has a back portion 96, first and second projecting

portions

98 and 100, and an outer corner 102 formed by the intersection of the back and first projecting

portions

96 and 98, respectively. Lamination 94 is stacked such that its outer corner 102 forms the upper left-hand corner of the preliminary structure, with its back portion 96 superposed over the back portion 52 of the first lamination 50, its second projecting portion 100 superposed over the second projecting portion 56 of the first lamination, and its first projecting portion extending towards and overlapping the end of the first projecting portion of lamination 64, by the dimension 78.

The four

laminations

50, 64, 84 and 94 form a basic group of laminations, providing a closed rectangular preliminary structure, upon which the desired number of additional basic groups of laminations are stacked to provide the desired build dimension 104, as illustrated in FIG. 1. The back portions of the first and fourth laminations provide the yoke 16, the back portions of the second and third laminations provide the yoke 18, the first projecting portions of the second and fourth laminations provide outer leg 20, the first projecting portions of the first and third laminations provide outer leg 22, the second projecting portions of the first and fourth laminations provide portion 28 of winding leg 24, and the second projecting portions of the second and third laminations provide portion 30 of the winding leg 24. It will be noted that the longitudinal dimension of the outer leg portions of the preliminary structure is almost twice the dimension that these legs will have in the final configuration of the magnetic core.

While the basic group of laminations includes four similar but differently oriented laminations to provide the four outer corners of the preliminary core structure, it is to be understood that each lamination may represent two, three or more laminations, which facilitates the handling and stacking thereof. For example, lamination 50 shown in FIG. 1 may represent three superposed laminations, and the remaining laminations of the basic group introduced in FIGS. 3, 4 and 5, would also each represent three superposed laminations.

The next step, after providing the desired build dimension of the preliminary magnetic core structure, which step is also illustrated in FIG. 5, is to rigidly clamp the superposed second projecting portions of the laminations together. This step, for example, may be accomplished by nut and bolt combinations. An insulating sleeve member (not shown) is inserted into each of the aligned openings in

portions

28 and 30 of the winding leg 24, insulating

lock plate members

40 and 42 are disposed over the

portions

28 and 30 of the winding leg, on the side shown in FIG. 5, as well as on the reverse side, and bolts are inserted through the sleeve members and tightened with nuts, such as the nut and bolt combination 44.

The next step, also illustrated in FIG. 5, is to dispose the electrical winding 12 within the opening defined by the rectangular preliminary structure, with the opening 112 in the winding 12 aligned with the facing ends of the

portions

28 and 30 of the winding leg 24. Winding 12 may then be telescoped over one of these portions, such as portion 30, and the preliminary structure compressed by moving the yokes l6 and 18 towards one another, to slide the interleaved portions of the laminations which make up the outer legs over one another until the desired non-magnetic gap 26 is achieved between the facing ends of

portions

28 and 30. The openings 62 in the outer leg portions will be aligned with one another when the proper gap dimension is achieved.

FIG. 6 illustrates the electrical inductive apparatus 10, after the step of compressing the preliminary structure to provide the final dimensions of the magnetic core. it will be noted that the step of closing the dimensions of the preliminary structure to the final dimensions of the magnetic core 14 stops before the ends of the first projecting portions abut the back portions of the laminations in the same layer. This is important, in order to prevent any mating faces in the magnetic core structure, to thus reduce the energized sound level of the apparatus, compared with a structure in which these faces are allowed to contact one another. The gaps between the ends of the first projecting portion and the back portions, such as the gap 114 shown in FIG. 6, add to the major non-magnetic gap 26 and are taken into consideration when setting the size of gap 26 to achieve the desired inductance versus current curve.

The final step, shown in FIG. 6, is to clamp the laminations rigidly together which make up the outer leg portions and the upper and lower yoke portions. This step may, for example, include the steps of disposing insulating sleeves in each of the aligned openings, placing insulating lock plate members over the outer surfaces of the laminations, disposing bolts through the sleeves, and tightening the superposed laminations with nuts disposed on the bolts. The apparatus used in the final step of clamping the yoke and outer leg portions together is most clearly shown in FIG. 1, which was hereinbefore described.

In summary, there has been disclosed a new and improved method of constructing electrical inductive apparatus having a gapped magnetic core, which structure has no mating faces. Non-magnetic gaps are established in each layer of laminations of the magnetic core, which are rigidly held in place by frictional forces established by clamping means. The major nonmagnetic gap is disposed centrally within the electrical winding, which is desirable because it provides the flattest inductance versus current curve. The method does not progressively build up the laminations about the winding which would make it difficult to rigidly clamp the lamination portions which extend into the opening of the winding. The magnetic core is constructed to first provide a preliminary structure which permits the lamination portions of the winding leg to be rigidly clamped together, before they are disposed within the opening in the winding, and yet the magnetic core is assembled into its final dimensions without the necessity of trying to interleave loose ends of laminations from two separate structures. The interleaving is started when the preliminary structure is stacked, and completed after the lamination portions of the winding leg are clamped while the winding leg portions are inserted into the opening of the winding.

Electrical inductive apparatus constructed according to the teachings of the invention, using 0.025 inch thick laminations, and stacking three F-shaped laminations at a time, was tested and found to operate with an energized sound level below the required maximum of db for the application, and the sound level was not deleteriously affected by shipment, as there are no mating faces in the structure to be displaced by shipping stresses.

We claim as our invention: 1. A method constructing electrical apparatus having a gapped magnetic core structure, comprising the steps of:

providing an electrical winding having first and second ends and an opening which extends between its ends, providing a plurality of flat, metallic F-shaped laminations, each of which has a back portion and first and second spaced parallel members which project outwardly from the back portion adjacent an end and midpoint thereof, respectively, providing a plurality of superposed groups of assembled F-shaped laminations by placing first and second- F-shaped laminations in the same plane with the end of their second members aligned and facing one anotherbut spaced by a distance equal to or greater than the length of the electrical winding between its first and second ends, inverting third and fourth ones of said F-shaped laminations, and stacking said third and fourth F-shaped laminations with their back portions and second members superposed on the back portions and second mem bers of said first and second F-shaped laminations, respectively, with the ends of the first members of said third and fourth F -shaped laminations overlappingthe ends of the first members of said second and first F-shaped laminations, respectively, placing said electrical winding between the facing ends of the second members of said F-shaped laminations, with its opening aligned therewith,

and closing the spacing between the facing ends of the second members of said F-shaped laminations to provide a winding leg within the opening of said electrical winding having a predetermined nonmetallic gap therein.

2. The method of claim 1 wherein the step of closing the spacing between the facing ends of the second members of said F-shaped laminations includes the step of sliding the overlapped ends of the first members of the F-shaped laminations relative to one another to provide a plurality of layers which include alternate layers of only the first and second F-shaped laminations, interleaved by layers which include only the third and fourth F-shaped laminations.

3. The method of claim 2 wherein the step of sliding the first members of the F-shaped laminations is termi nated before the end of the first member of one F- shaped lamination abuts the back of the other F-shaped lamination in the same layer, to provide a non-metallic gap therebetween.

4. The method of claim 3 including the step of clamping the superposed second members of the F-shaped laminations together, prior to the step of closing the spacing between the facing ends thereof.

5. The method of claim 4 including the step of clamping the superposed first members together, following the step of closing the spacing between the facing ends of the second members.

6. A method of constructing electrical inductive apparatus having a gapped magnetic core structure, comprising the steps of:

providing an electrical winding having an opening therein for receiving a winding leg of a magnetic core,

providing a plurality of F-shaped laminations having a back portion, first and second projecting portions disposed at one end and midpoint, respectively, of said back portion, and with the first portion extending outwardly from the back portion by a dimension which exceeds that of the second portion, stacking said F-shaped laminations to provide a preliminary rectangular structure having first and second yoke portions formed by the back portions of the laminations, first and second outer leg portions formed by the first portions of the laminations, and an intermediate leg portion formed by said second portions of the laminations having a gap therein formed between facing ends of said second portions, said intermediate leg portion being composed of two sections, one on each side of said gap s and each section having a plurality of superposed laminations,

said stacking step spacing the first and second yoke portions such that the ends of the first portions are overlapped by a dimension which provides a gap in the intermediate leg portion sufficient to receive the electrical winding, v placing the electrical winding in the gap of the intermediate leg portion, with its opening aligned with the facing ends of the intermediate leg portions, and moving the yoke portions closer together to provide a final rectangular structure which includes an intermediate leg portion having a gap therein, said gap being disposed within the opening of the windmg. 7. The method of claim 6 wherein the step of moving the yoke portions together is terminated before the ends of the first portions abut the back portions of the first and second yoke portions.

8. The method of claim 6 including the step of clamping the superposed laminations of each section of the intermediate leg portion prior to the step of moving the yoke portions together.

9. The method of claim 8 including the step of clamping the lamination portions together which make up the yoke portions and outer leg portions.