US2622135A - Two-part axial spacer for transformer windings - Google Patents

Description

Patented Dec. 16, 1952 TWO-PART AXIAL SPACER FOR TRANSFORMER WINDINGS Oliver M. Olivier, McKees Rocks, Pa., assigner to Allis-Chalmers Manufacturing Company, M-ilwaukee, Wis., a corporation of Delaware Application May 16, 1949, Serial No. 93,468

4 Claims.

This invention relates in general to stationary 'induction apparatus and particularly to spacers for positioning the coils of the windings of transformers and other induction apparatus.

In the prior art, coaxial windings of induction apparatus have been spaced from one another and from insulation barriers by the use of narrow pressboard strips or sticks. In this manner uniform annular spaces are formed between stacks of windings and between windingsv and barriers, and the stacks of windings are held in position. However, these spacer strips'or sticks are diicult to insert after the windings are assembled, and the spacers may be inserted improperly. They may become displaced or may shift from proper position, and as a result, the coils of the windings may become displaced.

In transformers or reactors where one of the windings comprises a stack of disk type coils, 'it is diiiicult to insert spacer strips or sticks between the stack of coils and the barrierwhich is next to `the stack of coils. Entry of the sticks is obstructed by the edges of individual disk coils in the stack which edges protrude slightly and irregularly into the space between the coils and `the barriers. When assembling these windings, layers of disk coils are superposed with radial spacers between the layers to provide space so that insulating fluid can circulate between layers. Each of the coils has an edge on the inner periphery of the stack and another on the outer periphery, and `it is not feasible' to perfectly align these edges when one coil is placed over another with radial spacers therebetween. As a result neither the'inner nor the outer peripheral surfaces of the' windings are perfectly smooth.

' Means 'have been suggested to guide the entry of the spacer sticks which are inserted between the stack of winding and the barriers. However, the prior art does not suggest how to provide proper and easy entry of the spacer sticks. The

.diiliculties resulting because of edges of coils or of radial vspacers protruding unevenly from the stack has not been avoided in the prior art. The protruding portions of radial spacers may become torn and displaced; the insulation on the disk coils may become torn, and the spacer sticks may be damaged.

It is very important that twisting or shifting movement of the stack of disk coils with respect to the other windings or insulating barriers in electric induction apparatus be completely avoided. Movement may result while the apparatus is in transit or under conditions of energization and luse when there are high stresses on the windings.

vinsulation barrier and other windings.

2 Therefore it isnecessary to firmly hold the stack of coils in position and also important that the stack be perfectly aligned with respect to the Any misalignment or displacement of the coils with respect to the insulation barriers or other parts 'of the structure of the apparatus will result in unnecessary `stresses in the apparatus when it is energized and used.

To assure the proper alignment Aof the coils 'of the stack and also to avoid the possibility of twisting or shifting of the coils in transit or when excited for use, the vertical spacing sticks between a stack of vcoils and va barrier should be slightly lgreater in thickness than the width of the annular cylindrical space between the stack of coils and the barrier. The oversized spacing stick can be inserted in the space between the coils and barrier, because of the resilience of the coils. The coils are thereby snugly positioned. However, since the cylindrical space between the coils and barrier is not wider than the spacer strip to be inserted therebetween, it is necessary to have means by which the strip can be inserted without being obstructed by the uneven or protruding edges of coils or radialspacers between layers of coils. The possibility of not inserting the stick properly and vertically must be avoided.

The disadvantages 'of the prior art have been avoided by the present invention. One of the objects 'of the invention is to provide an improved means for spacing a stack of disk coils rfrom other windings or from an insulation barrier in an electric induction apparatus.

Another object of the invention is -to provide improved means by which vertical spacers may be inserted between a stack of coils and an insulation barrier in electric induction apparatus.

Still another object of the applicants invention is to provide improved means for firmly and securely fixing windings in electrical induction apparatus.

These and other objects of the invention which will hereinafter become apparent are accomplished by means of a spacer for use in electric induction apparatus such as above referred to, wherein an element of the spacer can be anchored in position with respect to the windings and the barriers and anotherelement of the spacer can be inserted with one side bearing on the surface of the barrier and the opposite side bearing on a surface of the anchored element thereby causing forces to be exerted on the stack ofA coils to firmly, snugly and properly position the 'stack of coils.

In the drawing:

Fig. 1 is a view in longitudinal cross section of part of a core type transformer provided with spacers built in accordance with the present invention;

Fig. 2 is a partial cross sectional view of the transformer shown in Fig. 1 taken along line II-II of Fig. l;

Fig. 3 is an enlarged view in elevation of the spacer shown in Fig. 1 and of a portion of the adjacent barrier;

Fig. 4 is a plan View of the spacer and barrier portion shown in Fig. 3;

Fig. 5 is a View in elevation of the grooved strip element of the spacer shown in Fig. 3:

Fig. 6 is a side view of the grooved strip shown in Fig. 5; and

Fig. '1 is a plan view of the grooved strip shown in Fig. 5.

The transformer, of which only a portion is shown in Figs. 1 and 2, includes a magnetic steel core with high and low Voltage windings surrounding a leg of the core.

The low voltage winding I2, I3 is cylindrical in form. The two sections I2, I3 of low voltage winding are separated from each other by spacers I4 andare insulated from the laminated iron leg member` l5 of the core by the wound insula.- tion or foundation member I5. In the structure shown, wooden members I1 are used to space section I2 of the low voltage winding from the core steel.

A stack of high voltage windings of the disk type are shown. Radial spacers 2| are inserted between the layers of the disk coils separating the coils from each other thereby insuring the circulation of air or oil to the individual coils in the winding stack.

Cylindrical insulation barriers 24, 25, are positioned between low voltage Winding I2, I3 and the stack of high voltage coils 20 for insulating purposes. The insulation barriers are spaced from each other and from the low voltage windings by spacers 21 which are circumferentially spaced from each other and are radially7 aligned with spacers 2|.

In building transformers such as the one represented in Figs. l and 2 the sections of low voltage winding and the insulation barriers are not too diflicult to place in position as both the low voltage windings and the barriers all are of cylindrical form. However, the high voltage Winding, which is a stack of disk coils 2U, is not so easy to position with respect to the insulation barriers and the other elements of the transformer. The high voltage stack must be firmly and snugly held and properly positioned with respect to the other elements of the transformer. And since the high voltage stack is assembled by superposing one disk coil 2U over another with radial spacers 2l therebetween, the surface 3| defined by the inner edges of these individual disk coils, which surface will be referred to as the inner peripheral surface of the high voltage stack, is irregular compared with the smooth surfaces of the barriers and of the low voltage Winding.

Also, the stack of disk coils is usually assembled after the other parts of the structure are assembled, and it is desirable to space the stack kfrom the nearest barrier after the complete high voltage stack is assembled. The present invention provides a novel and efcient means for spacing the entire stack of high voltage coils from the nearest barrier after assembly. This will be hereinafter described in full. This spacing means is referred to by the reference numeral 33.

In the transformer shown the high voltage stack en the low voltage windings are supported and insulated from the yoke members 34, 35 of the core and from the heavy reinforcing channel members 36, 31 which are over the yoke members, by built-up insulation 38, 39 at each end of the winding assembly. In addition, insulation washers tl and spacers 42, 43 increase the spacing between the high voltage stack and the yokes and channel members. Standard insulation is intended to be represented by numerals 38 to 43. This includes yoke pads, washers, washer fillers, spacers and built-up blocks.

An electrostatic plate 44 may be placed next to the line end of the stack of coils in order to provide distribution of impulse voltages across the iirst coil.

The complete winding assembly, including the high voltage and low Voltage windings with the insulation and padding, is clamped between the channel members 36, 31 by strong tie rodstnot shown). Also, bolts (not shown) through the channel members are used to clamp the core and the mechanical parts. Clamping tie rods and bolts are employed in conventional manner for this type transformer.

The spacing means represented by numeral 33 is used for snugly xing the stack of high yvoltage disk coils 2D in place and uniformly spacing the stack from the insulation barrier.

The spacer means consists of a plurality of spacer assemblies circumferentially spaced about barrier 26. Each assembly is made of two parts. One part d5 is a grooved spacer element of pressboard or similar laminated cellulosicl insulating material. The other part 45 of the spacer means is a drive stick made of laminated synthetic resin or other insulating material. The drive stick 46 is driven between the grooved strip and the barrier, and thus tightens and positions the stack.

In Figs. 3 to 7 one of the spacers of means 33 is shown. Pressboard or other similar insulating material is out to the rectangular shape of the strip outlined in Fig. 5. Then the ycentral portion 41 of the strip is scored lengthwise thereof along lines 4g and i3 by a saw or knife cut. The pressboard is scored only through part of the thickness of the strip and then the material between lines 43 and 4S is removed from the strip. Numeral 6i) represents the depth of the saw` cut which will usually extend to a slightly vgreater depth than the thickness of the layers of laminations which are removed. Thus one side of Vthe strip member 45 has a rectangular recess 5I 'formed therein having sides along lines ,48 and 49 and a base therebetween along line 52. The opposite side 53 of the strip 45 has a flat surface. The grooved spacer strip with only the longitudinally extending portion removed may be satisfactory for use in many transformers. However, at times it may be desirable and important that the end portions 55, 5G of the grooved strips be` flat. In such instances, the strip member 45 is scored along lines 58, 59 crosswise of the direction of the lengthwise groove. The pressboard material between the scored line 58 andthe end 52 and between line 53 and the end 6I is removed to a depth not greater than the depth of scored lines 58, 5S so that the end portions 55, `55 are dat. Thus the ends of these strips which are bent along lines S4, and extend radially below and above the stack of disk coils have a substantially flat surface, and 'the 5stripils`iirmly and tightly heldinpesition by't-hest-ac'k.A

A "similar spacerstrip vcan be ina-de ylother methods, such as 4bybuilding up the-laf ations tothe iinal f'c-rm indicated'in Figs. 5, 'f6 and? j "In-the assembly of a transformer such 'asthe 'one shown, when the lowvolta'ge'winding I2, 51'3 and the insulation barriers 24, 2-5, v2li are in place surrounding the core member l5, several fof the groeved strip `"elemer'i'its-45 are circumferentially spaced from one another around the insulation barrier 26, withthe 'portion intermediate the end portions 55, 56 extending in a lengthwise direction parallel to the axis. of the barrier '2.6. The end portion 55 is bent at an angle 90 to the intermediate portion along line .65 and the end portion 55 extends over the yoke padding 3.9.. The insulation washers 4l and spacers "43 .aregpiaced overthe end portions 55 of theseveral grooved strip elements. Radial spacersZl are circumferentially spaced from each other'on 'topof tliespacer 43. rIhen the disk coils2'0"are Vplaced about the core member 15, the low 'voltage winding I2, I3 and barriers 24, 25, 26. The first disk coil 20 rests upon the radial spacers 2|, and the grooved strip elements are thereby anchored in position. The entire stack of disk coils is assembled. Spacers 42 and washers 40 are placed over the stack, and then end portions 56 of the strips are bent along line 64 at an angle of 90 to the intermediate portion of the strip so that the end portions 56 extend over the disk coils and the insulation washers and spacers.

After the high voltage stack is assembled a driving stick preferably with at least one end 61 tapered is driven between the barrier 25 and each grooved spacer element 45. The stick 46 is approximately as wide as the width of the groove. The thickness of the stick is greater than the depth of the groove. Therefore, when the stick is driven between the barrier and the strip, the stick forces the strip away from the barrier, thereby spacing the stack of disk coils from the barrier. Entry of .the stick after assembly o-f the stack of coils without damage to the stick or coil insulation is assured by the use of the grooved strip. The driving stick is retained in the groove of the strip while one side 69 of the driving stick bears against the comparatively smooth surface of the strip and the other side 68 of the driving stick bears against the smooth outer surface of the barrier.

The spacer means including the driving stick and the grooved strip can be slightly greater in thickness than the width of the space between the barrier and stack before the stick is inserted therebetween. Thus, when the stick is inserted, the width of the space is slightly .increased because of the resilience of the disk type coils of the high voltage winding. In this manner the stack of disk coils is firmly and snugly positioned. After the spacer is properly positioned, the padding 38 is placed in position over the winding assembly.

The yoke member 34 and channel member 36 are then put in position. Rods and bolts are added to the structure between channel members clamping the entire unit in the usual manner to give str ong mechanical support to the windings and coils.

Although but one embodi-ment of the present invention has been illustrated and described, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit :of the' invention for from the l'scope for the/ep pended claims. f It is lclaimed and-desired to lsecu-rie by Letters Patenti i 21.. An electric induction apparatus including' .a cy-lindrical insulation barrier, .a .stack of fdisk coilssuiround'ing said barrier-and radially spaced fromlsaid barrier to form an annular :cylindrical lpassageway between said barrier and saidstack of coils, means for spacing said coils from .'said barrier, said means including `spacers extending in a'jdirection vparallel to the longitudinal axis of said barrier, said spacers being circumferentially spaced from each other in said passageway, each of said spacers comprising a strip of insulating :material having a fla-t side bearing against the edges of said disk coils and extending frombne endl of said stack to the other end of said stack. the :opposite side of said strip having a recess extending lengthwise parallel to theaxis 'o'said stack, the end portions of said strip being bent and extended over the ends of said stack sothaft said strip 'i's `firmly held in positionrelative "to said stack, and a stick of insulating material having a thickness greater than the depth of said recess inserted in said recess and extending.

at least from one end of said stack to the other end thereof with opposite sides of said stick bearing against the surface of said barrier and against the base of said recess.

2. An electric induction apparatus including a cylindrical insulating barrier, a plurality of disk coils constituting a winding surrounding said barrier, said winding having resilience to forces acting radially on the edges of said coils, said winding being radially spaced from said barrier to define an annular cylindrical passageway between said barrier and said winding, and means for snugly holding said winding with respect to said barrier comprising a plurality of spacers circumferentially spaced in said passageway, one of said spacers comprising a strip of insulating material extending lengthwise at least from one end of said winding to the other end thereof, the end portions of said strip being bent and extending over the ends of said stack so that said strip is firmly held in positionrelative to said stack, a first side of said strip facing said barrier and having a groove therein extending lengthwise of said strip, the opposite side of said strip bearing against said winding, and a stick of insulating material inserted between and abutting against said barrier and said strip with said stick partly retained in said groove, said one of said spacers having a radial thickness slightly greater than the radial distance between said winding and said barrier, whereby insertion of said stick into said groove causes local radial deformation of said winding to maintain said one of said spacers in place by the resilience of said winding.

3. An electric induction apparatus including a winding having resilience to forces acting radially from the axis thereof, an insulating barrier coaxially disposed with respect to said winding, and means firmly positioning said winding in radial spaced relation with respect to said barrier by slightly increasing the distance between local areas of the adjacent peripheral surfaces of said winding and of said barrier, said means including a spacer comprising a strip of insulating material inserted between said barrier and said winding and extending in a direction parallel to the longitudinal axis of said winding from atleast one end of said winding to the other end thereof, said strip having a longitudinally extending groove in a side thereof facing said barrier, and an insulating stick retainedin said groove and bearing on said strip and said barrier, said spacer having a radial thickness slightly greater than the radial distance between said winding and said barrier, whereby insertion of said stick into said groove causes local radial deformation of said winding to maintain said spacer in place by the resilience of said winding.

4. An electric induction apparatus including a cylindrical insulating barrier, a plurality of superposed disk coils surrounding said barrier, said coils being formed of conductive material spirally Wound layer over layer and having resilience to forces acting radially on the edges of said coils, and spacing means for snugly holding said disk coils with respect to said barrier, said means including a strip of insulating material having one side bearing against the edges of said coils and having a recess in the opposite side of said strip extending parallel to the longitudinal axis of said barrier, and an insulating stick inserted in said REFERENCES CITED The following references are of record in the file of this patent:

v UNITED STATES PATENTS Number Name Date 1,426,940 Wulff Aug. 22, 1922 1,938,421 Gilbert Dec, 5, 1933 1,943,597 Gilmer Jan. 16, 1934 2,081,754 Lockhart May 25, 1937 2,116,404 Montsinger May 3, 1938

Images