US1891456A - Transformer construction - Google Patents

Description

Dec. 20, 1932. SWTH 1,891,456

TRANSFORMER CONS TRUCTI ON Filed Dec. 30. 1951 a Sheets-Sheet 1 INVENTOR BY ATTORNEYS Dec. 20, 1932. F. 5. SMITH TRANSFORMER CONSTRUCTION Filed Dec. 30, 1951 5 Sheets-Sheet 2 \N MN m m WM m m h m 3 MN mm mm mm mm k MJM INVENTOR Dec. 20, I932. .'s. SMITH 1,891,455

TRANSFORMER CONSTRUCTION Filed Dec. 30, 1931 3 Sheets-Sheet 5 llllliin.

INVENTOR BY ATTORN EYI Patented Dec. 20, 1932 PATENT OFFICE FRANKLIN S. SMITH, OF .NEW HAVEN, CONNECTICUT TRANSFORMER CONSTRUCTION Application filed December 30, 1931. 'Serial No. 583,840.

I .vention is to provide an apparatus of the above-mentioned character which will be capable of long uninterrupted use and in which possibility of breakdown .is substantially eliminated, and in which operating and maintenance expense is reduced to a minimum. Another object is to provide a potential transformer which is compact and rugged in construction and in which themternal windings are protected from excessively high electrical transient effects in a direct and extremely quick acting manner. Another object is to provide a potential transformer of high accuracy of action and capable dependably of insulating the volt- 336 meter or other instrument used therewith from the high tension circuit being measured. Other objects will be input obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will "be exemplified in the structure to be hereinafter described and the scope of the applica tion of which will be indicated in the follow- "46 ing claims.

In the accompanying drawings, in which is'shown one of the VilIlOllSPOSSlble embodlinents ofmy invention,

Figure l is'a vertical central sectional View of my transformerin which certain parts are shown in elevation, others in section, and others broken away tobetter show certain features of the construction; I

Figure 2 is a horizontal central sectional 1 view of the transformer, certain parts being shown in elevation and others insection;

Figure 3 is a vertical sectional view of. thetransformer construction as seen along the line 33 of Figure 2;

Figure 4; is an enlarged sectional view of certain features of a choke coil construction embodied in my device;

Figure 5 is a vertical sectional view as seen along the line 5-5 of Figure 1, and v Figure 6 is a fragmentary isometric view, partly in section, of the end core construction of the transformer.

Similar reference characters refer to simi lar parts throughout the several views of the drawings. i

As conducive to a clearerunderstanding of certain features of my invention, it may at this point be noted that, particularly in high voltage instrument transformers, it is vital to accuracy to have a construction in which the terminal voltage across the high voltage side of the transformer (which is connected to the supply whose potentials are to be measured) and the terminal voltage across the low voltage side {which is connected to the measuring. instrument) should be as nearly in phase as possible. In known instrument potential transformers such an in-phase re lation is so remotely approachedthat, par ticularly in high voltage transformers, there are present unreliability and great error with consequent lack of precision. One of the dominant aims of this invention is to provide a high potential instrument transformer in which the phase angle between the terminal voltages is so small, if present at all, as to be negligible and so that its effect is likewise negligible.

Another dominant aim of this invention is to provide a potential transformer construc'tion in which protection of the windings from surges, transients, and the like, is achieved in a simple and effectual manner without detracting from a construction in which the relation between the input and'output potentials is substantially co-phasial and without producing a construction that is bulky or cumbersome.

Referring now to the drawings and more particularly to Figure 1, 1 first provide a tank or casing 10 preferably cylindrical in shape and construction, in any suitable way and of any suitable material so as to withstand substantial pressures. For example, the easing 10 may be made of pressed steel and may thus have its bottom 11 formed integrally with the side walls thereof, its other end being closed by a closure or shell 12 which, after the apparatus has been mounted within the casing 10, is sealed and secured to the latter as by welding at 13.

Within the casing 10 is mounted the operative part of the transformer construction and the latter includes a core, preferably laminated and made of any suitable transformer iron, and preferably of the shell type. It therefore has upper and lower core legs 14=-15 (Figure 1), vertically extending end legs 1617, and a middle core leg 18. The laminations of which these core portions are made may be interlitted or interleaved in any suitable or known manner and the various core portions are rigidly clamped together by suitable structural steel sections and bolts, certain of which coact with certain other features of my invention, as is more clearly described hereinafter.

For example, the laminations of core members 16 17 have fitted against the assemblage thereof channel iron members 1919 for core member 16 (see Figure 6) and 2020 for member 17. The flanges of these channel members are cut off where these members overlap the upper and lower core legs 1415, as is better shown in Figure 6 with respect to the core leg 15, thus providing for the overlapping of the ends of these channel members by the clamping members associated with the core legs 1415.

The clamping members that hold the laminations of the core legs 1415 together may be made of any suitable cross-section adapted, like the channels 19-20 ,to resist bending and illustratively they are given an L-shaped cross-section, being virtually in the form of so-called angle iron. As is better shown in Figures 3 and 5, angle members 21 21 and 20-20 are associated respectively with the upper and lower core legs 1 1 and 15, and as appears better in Figures 1 and they extend lengthwise of the core legs, being, moreover, of a length greater than the latter so as to project beyond the right and left-hand ends of the transformer core, as viewed in Figure 1. Any suitable bolts or the like suitably located may be provided to draw these angle members and hence the channel members together so as securely to clamp the laminations of the core together and hold the latter in rigid assembled relation.

Preferably the extended angle members 20 and 21 are secured together at those portions where they extend beyond the transformer core by U-shaped members 22, one of which is clearly shown in Figure 6 and all of which are preferably of identical construction. The angle members are suitably drilled at their ends to receive cap screws 23 (Figures 6, 1, 5 and 3) which are threaded into the ends of the U-shaped yoke-like member 22, and if desired these cap screws and their coaction with the members 22 may be utilized to effect the above-mentioned clamping of the laminations of the transformer core. The members 22, two of which are thus provided at each end of the transformer core (Figure 1) serve a purpose more clearly described hereinafter.

The middle leg 18 of the core has the trans former windings extending thereabout. The low tension winding 24 (see Figure 1) may be wound upon a sleeve or tube-like member 25 of solid dielectric material, such as molded phenolic condensation product, and as thus wound it may be slipped over the middle core leg 18 in the course of the assembly of the transformer core. The winding 24 has any appropriate number of turns to suit the low voltage indicating instrument or voltmeter which is to indicate the voltage of the high tension circuit to which the high tension winding about to be described is connected. The low voltage winding may be wound for a potential on the order of 110 volts. Adjacent the right-hand end of the casing 10, the latter is provided with an insulating bushing generally indicated at 26 of any suitable construction adapted to seal the two'low voltage lead-in conductors insulatingly into the wall of the casing; the terminals of the low voltage winding 25 are connected by suitable conductors of the bushing 26 and by way of the latter connection may be made to the voltmeter or indicating instrument diagrammatically shown in Figure 1 at 27. The high voltage winding which is to be connected to the high tension circuit. the voltage of which is to be measured, also surrounds the middle core leg 18 and surrounds and is spaced from the low voltage winding 24; it has a sufiicient number of turns to give the desired ratio of transformation with respect to the low voltage winding and purely by way of illustration it may be constructed to be connected to circuits whose potential is on the order of 100,000 volts.

Preferably, the high voltage winding is made up of a suitable number of sections 28 (see Figure 1) which may be wound in any suitable manner and which are maintained in axial alinement with each other by a tube or sleeve 29 of suitable solid dielectric material such as molded phenolic condensation prodnot and onto which the winding sections 28 are strung.

The endmost sections 30 and 31 (see Figure 1) are preferably wound in the form of buffer coils which may and preferably do have fewer turns than the winding sections 28 and which may be wound with heavier wire than the latter; as is better shown in 1 losses.

Figure 1 these buffer coils and 31 individually occupy less space than a coil section 28. The buffer coils and the windingsections 28 are connected in series in a direction from the left to the right (or vice versa) as viewed in Figure 1. 1

Considering now how the high tension winding, thus made up of the coil sections and buffer coils strung onto the insulating sleeve 29 are supported, it is first to be noted that, after the apparatus has been assembled and mounted inside of the tank 10. and sealed, the latter is filled with a gaseous dielectric, such as nitrogen, under a pressure 1 on the order of 15 atmospheres and that the high dielectric strength of this gaseous di electric and its unique coactions with solid dielectric material when used in combination therewithmake it possible to achieve a construction and action which is of unprecedented significance in an instrument transformer, where phase angle is a vital 1 3013012.

It might first be pointed out, in this connection, that in a potential transformer change in the ratio of the terminal voltages with change of load should be precluded and a change in the phase relation of the terminal voltages of the two windings should like. wise be prevented, partlcularly 1f the trans- 3 former is used in connection with a wattmeter. These factors, however, are, in known constructions, greatly influenced by the magnetizing current component and the current component that supplies the core I am enabled, by the unique coaction between this gaseous dlelectric'under pres sure and related parts vastly to minimize the undesired effects of these current com ponents. I

This gaseous dielectric under pressure fills the space between the low voltage winding 24 and theinsul'ating sleeve 29 (Figure 1) so that these two dielectrics are in series in the field of high voltage gradient that exists between the two windings. The pern'iittivity of the gaseous dielectric is about unity while that of the sol d dielectric sleeve 29, if made of bakelite, is on'the order of 4. These dielectrics distribute between them the total voltage stress which they are to withstand inversely as their permittivities and as a re sult of this coaction I am enabled to make the spacing between the two windings much less than would be the case if, for example,

i sol-id dielectric alone were to be employed.

I am therefore enabled to greatly diminish the dimensions of the core windows with a correspondingly great decrease in the length of the magnetic path, thus greatly minim'zing the magnetizing current component and the core loss current component. Furthermore, I can as a result also make the mean length of turn in the high voltage winding less,'thus cutting down on the copper losses.

such factors as these, I am enabled to achieve a closer linkage between the two windings and bring down the above-mentioned disturbing factors to a practically negligible value.

In order further to achieve a lessening of the length of the magnetic circuit or, stated differently, to make it possible, for a given length (horizontally as viewed in Figure 1) of the core windows, to include a maximum number of high voltage turns in the high voltage winding, I support the high voltage winding in a manner whereby valuable space between the vertical core members 16 and 17 (Figure 1) is made-available for accommodating high tension winding sections.

The U-shapedmembers 22 (see Figures 1 and 6) are formed to provide an extension 22 directed away frorn' the vertical core members'16 and17, as viewed in Figure '1; these extensions 22 form seats for solid dielectric supporting beam structures generally indicated in Figure 1 at 32 and 33 and inasmuch as they-are of identical construction it will sufiice to describe in detail only one of them. Accordingly, reference may now be made to Figures 5 and 6 in which the beam structure 32 is better shown.

The beam structure preferably comprises two members 33 and 34 of angle cross-section and made of a solid d electric material, such as molded phenolic condensation product and they are bridged across the two members 22, being seated upon the extensions 22 as is better shown in Figure 6. Thus one flange of each of the members 33 and 3%, namely flanges 33 and 34? rest against the pillar or block portion 22 while the portions 33 and- 34 of these members, extending at right angles to the portions 33 and 3 B, respec tively, are back toback and may be held spaced relation by means of a spacer 35.

This composite beam structure is rigidly held in the above-described relation and position by means of angle clamping members 36, two at each end of the beam structure and each seated into the angle of one of the solid dielectric angle members; these angle clamping members 36 are secured to the parts 22 by cap screws 37 that extend through the component beam parts and that are threaded into the members 22 (see also Figure Bolts 38 (Figures 6 and 3) extend through the parallel ribs of the component beam members 33 and 34 and through the spacer and clamp these parts securely between the ribs.

of the clamping members 36. The latter are preferably flanged or provided with lips so as to overlap the edge portions of the anglebeam members and thus make the anchorage of the latter more secure and steady them pears clearly in Figure 6 and is also well shown in end elevation in Figure 2.

There is thus provided, as appears clearly in Figure 1, a solid dielectric beam construction (indicated at 32 and 33 in Figure l) at each end of the transformer core and each beam structure extending parallel to but spaced from the end core legs 16 and 17 respectively. These beam structures have an effective cross-section substantially T-shaped and thus offer excellent rigidity and great resistance to bending; moreover, they are of solid dielectric material and coact with the gaseous dielectric under pressure in a manner more clearly described hereinafter.

Extending centrally but crosswise of the beam structure 32 (Figures 1, 2 and 5) is a rigid cross-beam 39 preferably of metal; it extends preferably underneath the beam structure as it is viewed in Figure 5, or to the right thereof as viewed in Figure 1, and preferably rests against the alined faces of the ribs or flanges 33 and 34 of the members 33 and 34 to which it is secured as by cap screws 40 (Figure which extend through the solid dielectric members and are threaded into the cross-beam 39.

At its respective ends there are secured, as by bolts or cap screws 43 to the cross-beam 39, two metal members 41 and 42 (Figures 2 and 5) substantially U-shaped (see Figure l) and having legs or arms that extend toward the left-hand end of the high tension winding, as the latter is viewed in Figures 1 and 2, whence these arms or legs are extended, as by the extensions 41 and 42 (Figures 5 and 2) inwardly toward the axis of the high tension winding. These extensions 41 and 42 are shaped to present plane faces of relatively large area (see Figure 5) for engagement with the high tension winding (Figures 1 and 2) and preferably there is interposed between these extensions and the end buffer coil 30 (Figure 1) an annular member 44 of solid dielectric material adapted to distribute the pressure exerted by these extensions on the winding substantially uniformly about the latter.

A. substantially similar structure is carried by the solid dielectric beam structure 33 at the right'hand end of the transformer, as viewed in Figure 1, the beam structure 33 carrying a cross-member 45 like the abovedescribed member 39 of Figure 5 and the member 45 in turn supports two U-shaped members, one on each side of the core member 17, for supporting engagement with the righthand end of the high tension winding. In Figure 1 one of these U-shaped members is indicated at 46 and is broken away at its lefthand end to show the other U-shaped member 47 which is on the remote side of the core member 17 The members 46 and 47 are, like the members 42 and 43 at the other end of the high tension winding, provided with extensions adapted to engage the solid dielectric member 48 that is interposed therebetween and the other end buffer coil 31.

The high tension winding is thus dependably supported at its respective ends by at least four metal members substantially uniformly distributed (see the members 41 and 42 of Figure 5) about the end of the winding, and the sections thereof are held tightly compressed by these metal U-sha d members and the end beam structures 0 solid dielectric material; mechanical forces that might result from electrical reactions in the windings are thus dependably precluded from affecting the relation and position of the high tension winding or any of its parts. The rigid non-bending characteristics of the beam structures 32 and 33 coact to achieve these results and also to achieve the desired degree of force or pressure with which the winding sections 28, 30 and 31, alined on the insulating sleeve 29, are compressed. Moreover, the legs of the metal U-shaped members are provided with lips 49 (see Figure 1) to overlap the peripheries of the solid dielectric members 44 and 48 at the left-hand and right-hand ends of the high tension winding; these solid dielectric members, being also fitted onto the solid dielectric sleeve 29 (see the right-hand end of the latter in Figure 1) are by these lips 49 accurately centered and thus also center the supporting sleeve 29 and the high tension winding sections that are carried by the latter. Thus, a rigid and dependably mechanical support for and assembly of the high tension winding are achieved and its coaxial arrangement with the low tension winding and with the middle core leg 18 is dependably maintained. Moreover, the supporting structure leaves the annular space between the insulating sleeve 29 and the low tension winding 24 open at its respective ends so that a dependable and thorough circulation of the gaseous dielectric may be maintained, thus to carry away possible heat losses.

A conductor 50 (Figure 1) connects the free terminal of buffer coil 30 to the U-shaped member 42'while a conductor 51 connects the free end of the buffer winding 31 at the other end of the high tension winding to the U- shaped member 46. The purpose of these connections will be described in detail hereinafter.

In high tension potential transformers, transients, surges, and the like, should be precluded from entering the high tension winding but in accordance with certain features of my invention I achieve an adequate safeguard of the high tension winding against such transients but without impairment of the many advantages, some of which have already above been described in detail. The buffer windings 30 and 31 may be made relatively small in volume so as not to impair the volume of space available for the hightension winding and so not toincrease the length of the magnetic circuit andimpair related factors, but coacting with these buffer windings are choke coil structures generally indicated at 52 and 53 in Figure l. Thesechoke coil structures are of preferably identical construction and hence it will suffice to describe one of them in detail. Accordingly, reference may first be made to Figures 2 and 3 of the drawings in the former of which the choke coil construction 52 is shown partly in section. I p

Bridging over the solid dielectric beam structure 32 is a spider 54 (Figures 2 and 3) having four arms so shaped thatthe ends thereof engage the U-shaped members 41 and 42, being secured to the latter-by screws 55 (Figures 2 and 8); thecentral hub-like portion of the spider 54 is recessed and threaded to receive a supporting rod 56, the latter being of metal, as is also the spider 54 and both of these parts being thus electricallyconnected to the U- haped member which, by conductor 50 (Figure l)are electrically connected to the left-hand terminus of the high tension winding. I

At its right-hand end, the supporting rod 56 carries a disk 57 of solid dielectric ma-' terial, the latter abutting against the hub of the spider 54. At suitably spaced points in the periphery of the disk 57, the latter is recessed as at 57, there being provided preferably four such recesses equally distributed about the disk 57. Seated in these recesses are four solid dielectric bars 58, the left-hand ends of which rest upon a soliddielectric disk 59 carried by the left-hand end of the support 56 and having a radius equal to the dis tance from the center of disk 57 to the bottom of the recess57 thereof. A solid dielectric disk 6O is then fitted over the disk 59 and is of sufficient diameter to extend beyond the latter and to abut against the left-hand ends of the insulating supports 58. The disks 59 and 60 are held in place by nuts 6lvand 62 threaded onto the supporting stud 56 and between which the disks are clamped.

The supportingbars 58 are provided with a suitable number of radially extending slots, illustratively three in number and indicated in Figure 2 at 58. Into these slots are wound the turns of the choke coils 52, 52 and 52. T he choke coils are preferably made of fiat conductor having a cross-section preferably like that shown at 63 in Figure 4. g

The width of the-conductor 63is preferablysuch that it is snugly received in the slots 58 of the insulating bars 58, and it has a central flat portion 63 of substantially uniform thickness while its edges 63 (Figure 4) are of materially increased thickness and rounded over, the proportion and relation of the different parts of the conductor 63 being clearly and illustratively shown in Figure 4.

This conductor is wound in the slots of the insulating supports 58 with suitable insulating material in ribbon form, such as press board and indicated in Figure 4 at 64 interposed between the turns. This insulating material 64 is of sufficient thickness to prevent the rounded and enlarged edge portions 63 of adjacent turns from contacting'and in fact is so proportioned that there is provided between theserounded edge portions a gap of suitable dimension, the gap being filled with the gaseous dielectric under pressure. Certain features of coaction of these parts will be described in detail hereinafter.

Recurring to Figure 2, a conductor 65 (mm nects the innermost turn of the coil 52 to'the supporting stud 56, as by the nuts 6lland 66. Conductors 67 and 68 connect the three choke coil sections in series while a conductor 69 (see now Figure 1) connects the remaining terminus of the coil 52 to a rigid central conductor 70 that is passed through a metal bushing 71 welded into the wall of casing 10 and through a solid dielectric housing 7 2 sealed to the bushing 71; the outer end of the conductor 70'is provided with any suitable means to make connection to one side 7 3 of the high voltage line to which'the apparatus is to be connected. y

The gaseous dielectric under pressure'fills the space between the conductor 70 and the bushing 71 and also coacts with the housing 72 to achieve dependable insulation of the conductor 7 0 from the casing 10. The ratio of the radii of the inner surface of the bushing 71 and the conductor 70 is such as to form a fast discharge gap adapted to break down, without being preceded by corona formation, upon the achievement of a voltage equal to or in excess of a certain value. p 1

The choke coil construction 53 (right-hand portion of Figure 1) is of similar construction, being made up of the coil sections 53, 53 and 53 supported mechanically and electrically connected to the free terminus of the buffer coil 31 and to the conductor 74 of the high tension terminal construction 75in a manner substantially identical to that above described in connection with the choke coil structure 52. By means of the terminal construction 7 5, the other side of the transformer .iay thus be connected to the other side 7 6 of the high tension line.

As above already noted, theapparatus is sealed Within the casing 10 after the entire unitis inserted into the casing 10 through the right-handend thereof and suitably anchored to the casing in any desired manner, the end closure 12 being preferably welded in place. The gaseous dielectric under pressure may be injected into the casing by an suitable means not shown.

Certain coactions and advantages have a1- ready above been pointed out; to these might be added at this point certain advantages achieved by segregating the choke coils from the transformer construction per se. The choke coils are necessarily somewhat bulky in volume and in avoiding the assembly thereof alongside of the high tension coil sections, the great increase in the length of the magnetic circuit that would thus be necessary with its many detrimental effects upon phase angle, change in ratio of the terminal voltages, changes in phase, increase in magnetizing current, increase in the component of current supplying the core losses, and the like, are avoided. However, the choke coils are dependably supported mechanically and are subjected to the gaseous dielectric under pressure and thus further advantages are achieved.

The coaction of the gaseous dielectric under pressure with the insulating supporting bars 58 is such that the choke coil sections can be much more closely spaced than would otherwise be the case, and I am thus enabled to diminish the axial length of the choke coils. The latter absorb or prevent transients, surges, and the like, from entering the high tension winding and the buffer coils 30 and 31 coact therewith in preventing any possible surges or transients that might bypass the choke coils from entering the high tension winding sections 28.

Moreover, the flat conductor construction of the choke coils achieves a relatively high distributed capacity throughout the choke coils and this high capacity serves as a voltage capacity for coaction with the inductance of the choke coils in absorbing and choking back sudden electrical impulses.

The rounded edges of the conductor furthermore achieve long life in that they protect the solid dielectric material such as the press board or paper insulation 64 and prevent burning, charring, or carbonization thereof. For example, should over-stressing occur in the choke coils, the gaps between the cylindrical-like portions 63 (Figure 4) of the choke coils break down so that there is a direct discharge from conductor to conductor; this gap is filled with the gaseous dielectric under pressure and it is proportioned and shaped to break down at a potential less than that which would over-stress the interposed solid dielectric material and cause damage, charring. or the like, thereto. As soon as the transient or surge causing this break-down ceases, the gaps between these edges are restored to normal condition because of the self-restoring characteristic of the gaseous dielectric.

Should voltage conditions arise in the high voltage circuits 73-7 6 (Figure 1) either by way of a surge, transient, steep-wave-front voltage, or otherwise, that would damage the apparatus, the fast discharge gaps formed bepletely safeguarded not only as against transients, or the like, of average value, which are taken care ofby the inductive and distributed capacity characteristic of the choke coils and the coaction therewith of the bufier coils 30-31, but also as against excessive transients or abnormal conditions which are taken care of by the fast discharge gaps in the high voltage terminal constructions 72 and 75.

Though the U-shaped members 41, 42, 46 and 48 and the metal cross-beams 39 and 45 which secure them to the insulating beam structures 32 and 33 are at high potential, they are nevertheless dependably insulated from the core structure from which they are physically spaced by a distance which, due to the high dielectric strength of the gaseous dielectric under pressure, is much less, than would otherwise be the case. This advantage is particularly advantageous at the higher voltages which otherwise would impose exceedingly great dimensions and bulk upon the apparatus.

The solid dielectric beam structures 32 and 33 which support these high voltage part-s coact with the gaseous dielectric under pressure in achieving dependable insulation. They provide a relatively long leakage path but due to the coaction of the gaseous dielectric under pressure therewith the resistance thereof to surface leakage is so vastly increased that the dimensions of the beams in the direction of the leakage path can be much reduced. The beams may thus be made shorter and hence more rigid.

The gaseous dielectric under pressure and particularly its coaction with the solid d1- electric material make it possible for me to construct the choke coils with such compactness that their bulk and mass are greatly reduced; thus, also, I am enabled to support and relate these choke coils directly from or to the transformer construction though in a. manner as does not cause an increase in the length of the magnetic circuit. With a construction like that above-described I have been able to achieve in practice a phase angle or phase difference between the input and output voltages of less than five minutes and I make mention of this fact simply by way of illustration of the far-reaching character of changes might be made in the embodiment above setforth, it is to be understood. that all matter hereinbefore set forth, or shown in'the accompanying drawings, is to be interpreted as illustrative and not in a limiting sense.

I claim v 1. In transformed construction, in combination, a shell type of core, a lOW tension Winding related thereto, a hi h tension Winding spaced about the'n'iiddle leg thereof, metallic supports engaging the ends of said high tension Winding and spaced from said core, and a plurality of solid dielectric beams supported by and in spaced relation from said core for supp rting said metallic supports.

2. In transformer construction, in combination,-a shell type of core, a low tension Winding related thereto, a high tension Winding spaced about the middle leg thereof, metallic supports engaging the ends of said high tension Winding and spaced from said core, and solid dielectric means for securing said metal supports to said core, said solid dielectric means being shaped to provide a surface leakage path from said supports to said core greaterthanthe greatest short line distance therebetu 'een.

3. In transformer construction, in combination, a shell type of core, a low tension Winding related thereto, a high tension Winding spaced about the middle leg thereof, metallic supports engaging the ends of said high tension Winding and spaced from said core, two solid diel ctric beam-like members, one at each end of said core, means holding said beam-like members spaced from said core, and means securing said metal supports to said members.

4. In transformer construction, in combination, a shell type of core, a low tension Winding related thereto, a high'tension Winding spaced about the nliddle leg thereof, metallic supports engaging the ends of said high tension Winding and spacedfrom said core, two solid dielectric beam-like members, one at each end of said core, means for clamping the laminations of said core together and for holding said beam-like members spaced away from the latter, and meansconnecting said metal, supports to said beam-like members.

In transformer construction, in corn bination, a shell type of core having a middle core leg and end cross-members, a high tensionwinding about said middle core leg com-. prising a sleeve of solid dlelectrlc material and a plurality of coil sections on said sleeve,

and means for holding said Winding spaced from said core comprising solid dielectric members extending substantially parallel to said end members and spaced therefrom, and ieans carried by said members and engaging and centering said solid dielectric sleeve.

6. in transformer construction, in combination, a shell type of core having a middle core leg and end cross members, a high tension Winding about said middle core leg comprising a sleeve of solid dielectric material and a plurality of coil sections on said sleeve,

and means for holding said Winding spaced from said core comprisingusolid dielectric members extending substantially parallel to said end members and spaced therefrom, and a plurality of members spaced laterally away from said cross-members and extending from said solid dielectric members toward the respective ends of said Winding, said plurality of members being provided With means for centering said sleeve. I

7. In transformer construction, in combination, a shell type of core having a middle core leg and end cross-members, a high tension Winding about said middle core leg comprising a sleeve of solid dielectric material and pluralityof coil sections on said sleeve, and means for holding said Winding spaced from said core comprising solid dielectric members extending substantially parallel to said end members and spaced therefrom, and means extending from substantially central portions of said solid dielectric members toward and engaging the respective ends of said Winding for holding the latter against displacement.

8. In transformer construction, in combination, a shell type of transformer core having a middle leg and two transversely extending end members, a high tension winding about said middle leg, and means for supporting an end of said Winding, said means including a solid dielectric beam, means supporting said beam in a position spaced from an en d core member, and means supported by said'beam and extending about and spaced from said cross-member for engaging the end of said Winding. p

'9. In transformer construction, in combination, a. shell type of transformercore having a middle leg and two transversely extending end members, a high tension Winding about said middle leg, and means for supporting an end of said winding, said means including a solid dielectric beam, means supporting said beam in a position spaced from an end core member, and metallic means enthe end of said Winding and supported by said beam, said metallic means being spaced from said core.

10. In transformer construction, in combination, a shell type of transformer core having a middle leg and two transversely extending end members, a high tension winding about said middle leg, and means for supporting an end of said winding, said means including a solid dielectric beam, means supporting said beam in a position spaced from an end core member, a plurality of members extending lengthwise of said middle core leg and spaced from said transverse cross-memher for engaging the end of said winding, and means extending crosswise of said beam and engaging said plurality of members.

11. In transformer construction, in combination, a core, a winding related thereto, and

means for insulatingly supporting said winding from said core, said means including metallic means and solid dielectric means, one supported by the other, said solid dielectric means presenting a leakage path between the core and said metallic means of a length greater than the shortest straight-line dis tance therebetween.

12. In transformer construction, in combination, a core having a winding about a leg thereof, and means for supporting said winding, said means including two solid dielectric beams supported by and extraneousiy of said core, one at each end thereof, and two metallic means having parts spaced laterally of said core and extending into engagement with the respective ends of said winding, each metallic means being supported by one of said beams.

13. In transformer construction, in combination, a core having a high tension winding related thereto, and means supporting an end of said winding, said means including metallic means engaging the end of said winding and extending to each side of said core but spaced therefrom and solid dielectric means mechanically connectin said metallic means to said core, said solid dielectric means having a gaseous dielectric under pressure coacting therewith to restrict surface leakage therealon and the space between said metallic means and said core being filled with said gaseous dielectric under pressure.

let. In transformer construction, in combination, a core of the shell type, a high tension winding about the middle leg of said core, two solid dielectric beams each bridged lengthwise of an end or" said core and spacer therefrom, and means for holding said winding under compression and comprising means interposed between each end of said winding and the solid dielectric beam at that end of the core.

15. In transformer construction, in combination, a core of the shell type, a high tension winding about the middle leg of said core, two solid dielectric beams each bridged lengthwise of an end of said core and spaced therefrom, means extending inwardly from each of said beams for engaging and holding said winding, supporting means extending away from each of said beams, and a choke coil carried by each of said supporting means.

16. In transformer construction, in combination, a core of the shell type, a high tension inding about the middle leg of said core, two solid dielectric beams each bridged lengthwise of an end of said core and spaced therefrom, metallic means interposed between each solid dielectric beam and the end of the winding adjacent thereto and in electrical connection with that end of the winding, and a choke coil carried by said beam and in electrical connection with said metallic means.

17. In apparatus of the character described, in combination, an inductive winding made up of flat conductor whose side edges are of greater thickness than the main body portion thereof, solid dielectric means interposed between the main body portions of adjacent conductors and of a. thickness such that the gap between said thickened edge portions breaks down at a potential less than that which would injure the interposed solid dielectric means.

18. In apparatus of the character deicibed, in combination, an inductive winding made up of flat conductor whose side edges are of greater thickness than the main body portion thereof, solid dielectric means interposed between the main body portions of adjacent conductors and of a thickness such that the gapbetween said thickened edge portions breaks down at a potential less than that which would injure the interposed solid dielectric means, and a gaseous dielectric under pressure in which said winding is submerged.

19. In apparatus of the character described, in combination, a sealed casing having therein an inductive winding made up of a wound conductor, the turns of which are separated by solid dielectric material and having exposed portions, and a gaseous dielectric under pressure contacting with the solid dielectric and filling the gap between exposed portions of said conductor, the gap being proportioned and shaped to break down at a potential less than that which will injure the solid dielectric.

20. In apparatus of the character described, in combination, a sealed casing having therein a transformer construction including a core, a high tension winding related thereto, a chokecoil construction electrically related to said winding but magnetically separated from said core, a gaseous dielectric under pressure within said casing, and a common solid dielectric means supporting said choke coil construction and an end of said winding from said core, said gaseous dielectric under pressure contacting with the exposed surfaces of said solid dielectric means.

21. In apparatus of the character described, in combination, a. sealed substantransformer construction including a core of p tially cylindrical casing having therein a transformer construction including a core of the shell type positioned so that the axis of the middle leg of said core is substantially coincident with the axis of said cylindrical casing, a high tension winding about the middle leg of saidcore, a choke coil construction electrieallyrelated to said winding but magnetically separated from said core,

a gaseous dielectric under pressure within said casing, a solid dielectric beam bridged lengthwise of an end member of said core and spaced therefrom, means extending in,

a direction away from said end member of said core for supporting said choke coil construction from said solid dielectric beam and extraneously of said core, and means extending from said solid dielectric beam in a direction lengthwise of said middle leg of said core for supporting an endof said winding, said gaseous dielectric under pressure contacting'witli the exposed surfaces of said solid dielectric beam.

22. In apparatus of the character described, in combination, a sealed substan tially cylindrical casing having therein a the shell type positioned so that the axis of themiddle leg of said core is substantially coincident with the axis of said cylindrical casing, a high tension winding about the iddle leg of said core, a choke coil construction electrically related to said winding but magnetically separated from said core, a gaseous dielectric under pressure within said from and supported by said solid dielectric beams and to each side of said core but spaced therefrom for engaging the ends of said winding and holding the latter in place, two supporting structures, each extending away from one of said beams and each provided with a part that bridges over the beam and engages and is secured to said first-men- :tioned means, and a choke coil carried by each of said supporting structures.

24, In transformer construction, in combination, a core, a high tension winding about said core, two solid dielectric beams each bridged lengthwise of an end of said core and spaced therefrom, means extending from and supported by said solid dielectric beams with the exposed surfaces of said solid dielecand to each side of, said core but spaced therefrom for engaging the ends of said winding and holding tliezlatter in place, spider-like members each bridging over, one; of 7 said beams and each secured to said winding engaging means, and a choke coil construction carried by each of saidspider-like members.

i 25. In transformer construction, in combination, a core having a liightension wind} ng related, thereto, and means supporting an end of said windin said means including i metallic means engaging th e'end 'of said winding and extending to each side of said core but spaced therefrom'and solid dielectriomeans'meclianically connectingsaid metallic means to said core, said solid di'electrio means having a gaseous dielectric under pressure coacting therewith to restrict sure face leakage therealong and presentinga leakage path between said metallic means and said core of'a length greater than'the sliortest'straight line distance therebetween.

26. In transformer construction, incomjbination, a core, a winding. related thereto,

and means for insulatingly supporting-said winding from said core, said means including i metallic meansandsolid dielectric means, said solid dielectric means being inlthe' form of a beam carried by said core andsupportj'ing said metallic means at a point in said beam such that said beam presentsa leakage path therealong between the core and said "metallic means of'a length greater than the shortest straight line distance therebetween.

27. In apparatus of the character described, in combination, a sealed'casing having therein a transformer construction ineluding a core, a high tension winding related thereto, a choke coil construction electrically related to sa d winding but magnetically sep-' 1G5 aratedfromsaid core, agaseous dielectric under pIGSSUIGWIthID said casing, metallic means extending from an end of said winding and spaced from and about said core and supporting said choke coil construction, and

soliddielectric means secured to said core for holding said metallic means in position, said gaseous dielectric under pressure contacting trio means, i 28. In apparatus of the character de-i scribed, n combination, a sealedcasmg havingtherein a transformer construction ineluding a core,.a high tension winding related thereto, a choke *coil construction electrically related to said winding but magnetically sep-; arated from said core, a gaseous dielectric under pressure within said casing, metallic means extending from an end of said winding and spaced from and about said core and supporting said choke coil construction, andri; a solid dielectric beam anchored at its ends and engaging said metallic means intermediate said ends for holding said metallic means in place, said gaseous dielectric under pressure contacting with the exposed surfaces of said solid dielectric beam.

4 29. In apparatus of the character described, in combination, a sealed casing having therein a transformer construction including a core, a high tension winding related thereto, a choke coil construction electrically related to said winding but magnetical- 1y separated from said core, a gaseous dielectric under pressure within said casing, metallic means extending from an end of said winding and spaced from and about said core and supporting said choke coil construction, and solid dielectric means secured to said core-for holding said metallic means in position and said solid dielectric means presenting a leakage path between said core and said metallic means of a length greater than the shortest straight line distance therebetween,

said gaseous dielectric under pressure contacting with the exposed surfaces of said solid dielectric means.

30. In transformer construction, in com- 'bination, a core having a Winding-receiving leg and an end member extending transversely thereto, a winding about said core leg, means for insulating said winding from said core and for supporting said winding from said core, and a gaseous dielectric under pressure, said means including solid dielectric means and said gaseous dielectric under pressure in series with said-solid dielectric means, said serially related dielectrics being interposed between said winding and said core leg whereby the mean length of turn of winding is decreased, and said supporting means in cluding metallic means engaging the end of said winding and extending to one side of and spaced from said transverse end member of said core and solid dielectric means carried by said core and supporting said metallic means, said second-mentioned solid dielectric means having said gaseous dielectric under ressure coacting therewith to restrict surace leakage therealong and presenting a leakage path between said core and said metallic means of a length greater than the shortest straight line distance therebetween, whereby the length of said winding along said core leg is increased.

In testimony whereof, I have signed my name to this specification this 11th day of December, 1931.

FRANKLIN S. SMITH.

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