US762697A - Reactance-coil. - Google Patents

Description

UNITED STATES Patented June 14, I904.

PATENT OEEicE.

JOHN J. FRANK, OF SCHENEOTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEIV YORK.

REACTANCE-COIL.

SPECIFICATION forming part of Letters Patent No. 762,697, dated June 14, 1904.

Application filed October 16, 1902. Serial No. 127,455. (No model.)

To all whom it may concern.-

Be it known that I, J OHN J. FRANK, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Reactance-Ooils, of which the following is a specification. v

Heretofore reactance-coils have been constructed in which a high reluctancewas obtained by forming relatively large air-gaps in the magnetic circuit. In one form of reactance-coil which has been employed the core is substantially a cylinder, and the lines of force have an air-path from one end of the cylinder to the other. Among other forms which have been used are those in which the core is shaped like the letters U and E. These forms of cores have all been open to the objeetion that the leakage or stray field was of considerable magnitude, and with reactancecoils of large capacity this stray field is of such magnitude that no metal casing can be employed near or around the coil owing to the heating effect induced therein by the stray field. Vith large reactanee-coils having a large stray field another difiiculty met with lies in the fact that it is impossible to place them on a floor supported by steel or iron girders owing to the heat effect produced in the girders by the eddy-currents which result from thestray field; nor can any large body of unlaminated metal be placed near such reactance-coils without injurious results.

In a reactance-coil constructed in accordance with my invention the necessary reluctance is obtained by forming a plurality of small air-gaps in the magnetic circuit. By this means the reluctance of the magnetic circuit may be increased to a considerable extent, while at the same time the absence of any one large air-gap reduces the tendency to the creation of a large stray field.

For a better understanding of my invention reference may be had to the accompanying drawings, in which I have illustrated forms of my invention.

Figure 1 is a plan view, partly broken away and partly in section. Fig. 2 is a sectional elevation taken on the line 2 2 of Fig. 1. Fig. 3 is a plan view showing one form of lamina employed, while Fig. 4 shows a different form.

In the drawings, 1 represents a base upon which is mounted a three-phase air-cooled reactance-coil. Upon lugs 2, formed upon the inner side of the base, are mounted members 3, which in turn support members 4:, upon which the core of the reactance-coil is placed. The core of the reactance-coil consists of groups of laminae 5, the groups beingseparated from one another, as shown, to form suitable ventilating-spaces 5. Each separate lamina is a punching formed from one integral piece of material and having three pairs of openings 7, in which the the three sets of windings of the three-phase system can be placed. The laminae are separated from the member 4: by pieces of wood or other suitable insulating material 8. Blocks 9, similar to the blocks 8, are placed on top of the core to 7 separate the core from the top member 10 of the casing.

In assembling the laminae alinement is secured by means of wooden pins which are placed in the openings 6, formed in the corepunehings. When the parts are assembled, the core is clamped between the members 4: and 10 by means of bolts 11. Each of the channels formed by the successive openings 7 is lined with insulating material 12, and in these lined channels are placed conductors 13.

The conductors 13 consist of U shaped strips of copper which are inserted from the top and are connected together at the bottom 7 by cross-bars 14:, which are soldered to and 5 connect opposite sides of adjacent U-bars. The conductors are spaced apart, as shown in Fig. 1, in order that the air may circulate between them. I have not thought it necessaryillustrate the spacing-blocks employed. Suit- 9 able terminals 15 lead from the opposite ends of each coil thus formed. Blocks of Wood16 and 17 are employed to position the connecting-strips 1 1 and terminals 15. A removable cover 17 rests in the opening 18, formed in 9 the upper side of the member 10. A suitable casing 19, preferably of sheet metal, surrounds the core of thetransformer extending from the member 10 to the base member 1.

This reactance-coil is intended to be placed) over a fan-chamber and to have air forced or drawn through the coils and core parts in order to cool it.

In Fig. 3 of the drawings I have shown the form of punching which I prefer to employ in the construction of these reactance-coils. A plurality of comparatively small oblong slots or perforations are formed in that portion of the core which is surrounded by the winding. These slots are quite narrow and are placed with their longest dimension at right angles to the path of the magnetic flux. In this figure I have shown these openings or air-gaps formed in rows, with the air-gaps in successive rows breaking joints with one another. By this arrangement the reluctance in the magnetic circuit is increased, while at the same time a core is obtained which is mechanically strong and in which by reason of the distribution of the air-gaps the tendency to the creation of a stray field is comparatively small. By reason of the smallness of the air-gaps and their arrangement and by reason of the narrowness of the necks connecting the air-gaps the most of the flux will pass through the air-gaps, and the local heating at the edges of the air-gap will be slight. Moreover, as the punchings are similar the air-gaps in successive laminae register with one another and form channels, through which the air can circulate and carry oif heat generated therein.

In Fig. 4 I have shown a modified form of punching in which the air-gaps are of the same general dimension as those shown in Fig. 3; but those in successive rows are not staggered with respect to one another.

While I have shown my invention as embodied in a three-phase air-cooled reactancecoil, Ido not consider it in its broader aspect as limited thereto. For instance, my inven tion can be applied to a single-phase reactance-coil or to a multiphase reactance-coil other than that shown or, indeed, in many cases Where amagnetie circuit possessing the advantages of those described is desired. It is not essential that the magnetic circuit be of the so-called shell type shown, as the invention can be applied to other types, the particular form of the magnetic circuit being in general immaterial; neither is it essential that each layer or lamina be formed of one integral piece as a core in which each ls eris formed of several pieces and could also be provided with my invention.

While I have shown my invention as applied to an air-cooled reactance-coil, meaning one in which artificial means are employed to force air through the reactance-coil, it is obvious that a core having its reluctance increased by the formation of the small gaps in the magnetic circuit could be employed in a reactancecoil of the oil-cooled type or in one in which no artificial means for cooling the reactance- COIl are provided. IVhere in the claims I have used the term air-gap, I do not intend to exclude those reactance-coils in which this gap may be filled with oil or other dielectric, as I consider that such forms are full equivalents of the air-gaps shown and described in my case. It is obvious that other arrangements of the case. the winding, &c., could be employed without departing from the spirit of my invention.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. In a three-phase reactance-coil having a laminated core, laminae each consisting of a single piece of material having three pairs of conductor-receiving openings formed therein and having formed between each pair of said openings a plurality of small distributed airgaps.

2. A fluid-cooled reactance-coil having a laminated core and having air-gaps formed in the lamina: to increase the magnetic reluctance, the air-gaps in successive laminae registering with each other to form channels or passages through which the cooling fluid may pass.

3. In combination, a laminated magnetic core, and means for producing a magnetic flux therein, each lamina of said core having a plurality of small air-gaps formed therein and arranged in rows extending transversely to the direction of the magnetic flux.

4:- In combination, a magnetic core made up of laminae, and means for producingamagnetic flux therein, each lamina of said core being provided with a plurality of comparatively small air-gaps arranged in rows extending transversely to the direction of the magnetic flux and with the air-gaps in one row breaking joints with those in adjacent rows.

5. In a reactance-coil, the combination with the windings, of a core consisting of iron sheets having a plurality of short air-gaps distributed laterally and longitudinally along the sheets to obtain the requisite reluctance in the magnetic circuit.

6. In a reactance-coil a core comprising laminae having a plurality of small air-gaps distributed over a considerable portion of their extent, and a magnetizing-coil therefor.

7. A magnetic core havinga perforated portion and an unperforated portion, and means for generating a magnetic flux passing substantially entirely in series through said perforated portion and through said unperforated portion.

8. In combination, a magnetic core comprising a perforated portion and an-unperforated portion and a magnetizing-winding surrounding said perforated portion.

In witness whereof I have hereunto set my hand this 15th day of October, 1902.

JOHN J. FRANK.

WVitnesses:

BENJAMIN B. HULL, HELEN ORFORD.

Images