US1741200A

US1741200A - Transformer

Info

Publication number: US1741200A
Application number: US344413A
Authority: US
Inventors: Konstantin K Palueff
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1929-03-05
Filing date: 1929-03-05
Publication date: 1929-12-31
Anticipated expiration: 1946-12-31

Description

Dec. 31, 1929.

K. K. PALUEFF 1,741,200

TRANSFORMER Filed March 1929 3 Sheets-Sheet 1 I nventor: Konstantin KPalueff: yWwZm/ H is Attorney.

Dec. 31, 1929. K. K. PALUEFF TRANSFORMER .5 Sheets-Sheet Filed March 5, 1929 Inventor": Konstantin Kpaluef'f, YM/WMZZM Hi sAttorrw ey.

Dec. 31, 1929. K. K. PALUEFF TRANSFORIER File l r 1929 5 Sheets-Sheet Inventor. Konstantin Kpalueff,

H i sAttorney,

Patented Dec. 31, 1929 UNITED STATES PATENT OFFICE KONSTANTIN K. PALUEFF, 0F PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK TRANSFORMER Application filed March 5, 1929. Serial No. 344,413.

My invention elates to electrical induction apparatus and is particularly applicable to transformers and the like. The general object of the invention is to provide an improved construction of apparatus of this character which is particularly adapted for high voltage operation. One object of theinvention is to provide the high voltage winding of the apparatus with an improved electrostatic shielding structure in accordance with the principles explained in Letters Patent of the United States to James M. Weed, No. 1,585,448, dated Ma 1.8, 1926.

Other objects and a vantages will appear from the following description taken in connection with the accompanying drawings in which Fig. 1 is a view of one side of a transformer constructed in accordance with the invention; Fig. 2 is a view of the other side of the transformer shown in Fig. 1; Figs. 3, 4 and 5 are detail views of one of the electrostatic shielding members, Figs. 4 and 5 being cross sectional views on the lines 44 and 55 respectively of Fig. 3; Fi 6 is a vertical sectional view of the trans ormer shown in Figs. 1 and 2; Fig. 7 is a sectional view of the line 77 of Fig. 6; and Fig. 8 is 3. diagrammatic View of the high voltage winding with its electrostatic shielding structure.

Like reference characters indicate similar parts in the different figures of the'drawings.

The transformer shown in the drawings includes a laminated magnetic core having two winding legs 10 and 11 connected by end yokes 12. The two winding legs are surrounded respectively by two

cylindrical sections

13 and 14 of a low voltage winding. The high voltage winding is also formed in two

cylindrical sections

15 and 16, the section 15 surrounding the winding leg 10 and its section 13 of the low voltage winding and the section 16 surrounding the winding leg 11 and its section 14 of the low voltage winding.

The high voltage terminal 17 of the-transformer is connected tothe center of the section 16 of the high voltagewinding as shown in Figszl and 8. Both ends of this high voltage winding section 16 are connected to the paths to the two ends of this winding section and the center of the winding section 15 and thence through two parallel paths to the two ends of this latter winding section and to the grounded terminal 19. With this arrangement, the coils in each winding section which have the lowest voltage are nearest the yokes 12 of the core and a minimum amount of insulation is therefore required between the winding sections and yokes.

It is desirable that the high voltage winding be close to the low voltage winding in order that the reactance of the transformer may be small. With this close-spacing, too, the amount of conductive and insulating material and the resistance in the high voltage winding is a minimum. Both ends of the high voltage winding section 15 are at ground potential and may therefore be very close to the low voltage winding section 13. These

winding sections

13 and 15 must be spaced progressively further apart towardtheir centers, however, where the voltage of the high voltage section 15 is a maximum. The spac ing of the high voltage winding section 16 from the low voltage winding 14 must likewise increase progressively from their ends toward their centers where the voltage of the high voltage winding section 16 is a maxiinum. The voltage of the two ends of the high voltage winding section 16 is, however, substantially the same as that of the center of the high voltage winding section 15 and therefore the spacing between the ends of the

sections

16 and 14 must be at least as great as that between the centers of the

sections

15 and 13. It follows, of course, that the average spacing between the

winding sections

16 and 14 is considerably greater than that between the

sections

15 and 13 and that the reactances would also be unequal if the two high voltage sections 15 and 16'had the center of the high voltage winding section 15. same number of turns and the two low voltby a conductor 18 as shown in Figs. 2 and&

age sections

13 and 14 were alike, the greater reactance being between the more

widelyspaced winding sections

16 and 14. Such an unbalance of the two reactances would be undesirable and they are therefore equalized by using a greater number of turns in the winding section 15 than in'the winding section 16. The numbers of turns in the two

winding sections

15 and 16 are so proportioned that the reactance due to the greater number of turns in the winding section 15 and their closer spacing to the low voltage winding section 13 is equal to the reactance due to the smaller number of turns in the winding section 16 and their wider spacing from the low voltage windin section 14. Inasmuch as the winding section 16 has fewer turns than the winding section 15, it may be made shorter and its ends spaced further and more highly insu; lated from the yokes 12 of the core as shown most clearly in Fig. 6. The coils of both the high voltage winding sections are all alike except that their diameters decrease gradually from the center to each end of each section. The turns of each section as well as the turns 7 of the

low voltage sections

13 and 14 are therefore uniforml distributed along the winding legs of the ore and this is of advantage in avoiding magnetic displacement forces between the high and low voltage windings.

The transformer includes an improved shielding structure for the high voltage winding which will prevent the occurrence of excessive transient voltage stresses between its turns in accordance with the principles explained in the Letters Patent to James M. Weed alread referred to.

The shiel ing structure cannot limit the voltage which may be applied to thehigh voltage terminal 17 of the transformer but it effectively maintains at all times a substantially uniform distribution of the applied voltage throughout the high voltage winding. This is of very great importance because no part of the winding is ever subjected to more than its proper proportion of the total voltage. The shielding structure includes conductive members adjacent to the two

sections

15 and 16 of the high voltage winding and conductively connected to the high voltage terminal 17. The shielding members are distributed along and near the surfaces of the two

sections

15 and 16 of the high voltage 1 winding so that there is a definite capacity between eachcoil of the winding and the adj acent shielding member. Thus, whenever a high voltage is suddenly applied to the high voltage terminal 17, the conductive members of the shielding structure are instantly charged to the same high voltage and a charging current is instantly supplied through the capacity to each part of the winding. Thus, each part of the winding is instantly raised to a potential which is determined by the capacity through which the current has to flow.

areas of the adjacent surfaces and on theirspacing. It is considered'desirable, as shown in Figs. 6 and 8,that the spacing of the shielding structure gradually increases toward the grounded end of the winding because all parts of the shielding structure are at the same potential which may be very high and it therefore needs to be more highly insulated from the grounded end than from the high voltage end of the winding. I

The winding section 16 is provided with a part of the shielding structure which is an improved and modified form of that disclosed in Letters Patent of the United States to Louis F. Blume and John S. Lennox. No. 1,511,717, dated October 14, 1924. Both

winding sections

15 and 16 are formed of disc coils which are spaced apart to provide ducts between them for the circulation of insulating oil to cool them. The shielding structure is rather close to some of the coils nearest the center of the winding section 16 and is therefore formed of conductors 20 which are spaced apart so that the oil from the winding ducts may flow between them and not be impeded. The two ends of each conductor 20 are near opposite faces of the transformer core, the conductors extending along the outer edges of their respective coils from which they are spaced bv insulating strips 21. Each end of each of the conductors 20 is curved away from its coil as shown in Fig.

.7 to avoid disturbance or distortion at the surface of the winding. One end of each conductor 20 is connected to the high voltage terminal 17 through a connection 22. The other end of each conductor 20 is embedded in an insulating channel 23.

The parts 24 of the shielding structure which are between the shielding conductors 20 and the ends of the winding section 16 are spaced further from this winding section than are the-conductors 20 so that they are not apt to impede the flow of oil from the ducts between the coils of the winding. These parts 24 of the shield are therefore substantially cylindrical in form. Each part 24 has a substantially cylindrical inner supporting member formed of strong sheet insulating material such as press board. This inner support is wound with narrow strips of conductive material such as German silver and this is covered by insulation. The conductive strips are connected to the high increases gradually toward the grounded ter-;

minal 19. The insulating support 27 is wound transversely with flat narrow strips 28 of conductive material having high re sistance as shown in Figs. 3, 4 and 5. This forms a conductive layer on the support 27, the layer having low eddy losses because of its high resistance and division into narrow strips. Another advantage of the strips 28 is that they may be properly spaced to provide the correct total conductive area to give the desired capacity between them and the adjacent winding. conductive covering formed by the strips 28 are covered by insulation as shown in Fig. 6. The conductive strips 28 are connected to the high voltage terminal 17 of the transformer by a conductor 29 so that the conductive strips are always maintained at the same potential as that of the high voltage terminal.

The turns formed by the conductive strips 28 are connected together by a wire 30, soldered to them along one edge of the support 27. Some connection between the turns, such as this wire 30, is necessary, of course, if the turns are formed separately. If the turns are formed by winding them successively from a single continuous strip, the wire 30 will provide a non-inductive path for any charging current flowing to each turn from the high voltage terminal 17. By winding the turns transversely of the support 27, they are arranged longitudinally of the adjacent winding so that little or no voltage will be induced in them by leakage flux from the winding.

Each insulating support 27 extends entirely around the Winding so that it may be effectively and easily secured in place. The conductive covering formed by the strips 28 does not extend into the space between the two winding

sections

15 and 16, the ends of the covering being spaced apart as shown in Fig. 3 and avoiding the necessity of heavy insulation in the restricted space between the two winding sections. The ends of the conductive covering extend further at that edge of the support 27 which is nearest the center of the adjacent winding section because the capacity must be greater between the covering and winding at this edge than at the other. At each end of the conductive covering, a wire loop 31 extends around and obliquely across the support 27. High resist- The support 27 and its ance conductive strips 28 extend around the edge of the support- 27 nearest the center of the adjacent winding, the inner and outer ends of these strips being soldered to the wire loops 31. As indicated in Figs. 3 and 5, the part of each wire loop 31 at the outer surface of the support 27 is a little further from the center of the adjacent winding section than is the other part of the wire loop at the inner surface of the support. This reduces the electrical stress at the inner part of the wire loop which is nearest the adjacent winding section.

The invention has been explained by describing and illustrating a transformer construction embodying the various details of the invention in what is now believed tobe their preferred forms but it will be apparent that changes may be made without departing from the invention and therefore aim in the appended claims to cover all such changes as fall within the true spirit and scope of my invention.

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

1. A transformer including a magnetic core having a winding leg, and two concentric groups of winding turns surrounding said winding leg, the turns of each of said groups being uniformly distributed along said winding leg, the outer group of turns having one terminal grounded, and the spacing between said grou s of turns increasing progressively from said grounded terminal to the other terminal of said outer group.

2. A transformer including a magnetic core having two winding legs, and two winding sections concentrically surrounding each of said winding legs, one of the outer winding sections having its center connected to a high voltage terminal and having each end connected to the center of the other outer winding section, said latter winding section having both ends connected to a grounded terminal.

3. A transformer including a magnetic core having two winding legs, two winding sections concentrically surrounding each of said winding legs, one of the outer winding sections having its center connected to a high voltage terminal and having each end connected to the center of the other outer winding section, said latter winding section having both ends connected to a grounded terminal, and an electrostatic shield extending from the center toward both ends of each of said winding sections and adjacent the surface thereof, both of said shields being elecllO trically connected to said high voltage tera high voltage and a grounded terminal, said outer two winding sections being unequally spaced from the two inner sections which they respectively surround, the outer section which is connected to the high voltage terminal having the greater spacing.

5. A transformer including a magnetic core having two winding legs, and two winding sections concentrically surrounding each of said winding legs, the outer two winding sections being connected in series between a high voltage and a grounded terminal, said outer two winding sections being unequally spaced from the two inner sections which they respectively surro d, the outer section which is connected to the high voltage terminal having the greater spacing and having a smaller number of turns than the other outer section.

6. A transformer including a magnetic core having two winding legs, two winding sections concentrically surrounding each of said Winding legs, the outer two winding sections being connected in series between a high voltage and a grounded terminal, said outer two winding sections being unequally spaced from the two inner sections which they respectively surround, the outer section which is connected to the high voltage terminal having the greater spacing and having a smaller number of turns than the other outer section, the reactance due to the greater spacing and fewer turns of one outer section being substantially equal to the reactance due 35 to the smaller spacing and greater number of turns of the other outer section.

7. The combination in electrical apparatus of two groups of winding turns connected in series betwen a high voltage terminal and a grounded terminal, and an electrostatic shield spaced beside each of said groups of turns, each of said shields being electrically connected to said high voltage terminal.

8. The combination with an electrical winding having a high voltage terminal and a grounded terminal, of an electrostatic shield spaced beside said winding, said shield including a plurality of substantially parallel conductive strips electrically connected to said high voltage terminal.

9. The combination with an electrical winding'having a high voltage terminal and a grounded terminal, of an electrostatic shield spaced beside said winding, said shield including a plurality of substantially parallel conductive strips extending longitudinally of the winding and electrically connected to said high voltage terminal.

10. The combination with an electrical winding having a high voltage terminal and r. grouded terminal, of an electrostatic shield spaced beside said winding, said shield including an inner support of insulating sheet material, and conductive strip material wound on said support with its turns ex-