US2815492A

US2815492A - Inductive device

Info

Publication number: US2815492A
Application number: US467304A
Authority: US
Inventors: Henderson Wayne Lee Roy
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1954-11-08
Filing date: 1954-11-08
Publication date: 1957-12-03
Anticipated expiration: 1974-12-03

Description

Dec. 3, 1957 WAYNE LEE ROY HENDERsoN ,8

INDUCTIVE-DEVICE Filed Nov. 8,1954 2 Sheets-Sheet 1 His Attorney- 7 WAYNE LEE ROY HENDERSON 2,815,492

INDUCTIVE DEVICE Filed Nov. 8, 1954 2 Sheets-Sheet 2 I J j as [)2 1 67? tor fiVa n e. L. Efiendersozz Patented Dec. 3, 1957 ice nsnucrrvn DEVICE Wayne Lee Roy Henderson, Danville, Ill., assignor to General Electric Company, a corporation oi New York Application November 8, 1954, Serial No. 467 ,304

11 Claims. (Cl. 336-165) This invention relates to inductive devices, such as reactors and transformers.

Reactors and transformers are alternating current inductive devices, the former serving merely as an impedance to limit the current in an alternating current system, while the latter serves to step-up or step-down the voltage of an alternating current system. A special form of transformer, commonly referred to as a high reactance transformer, not only steps-up or steps-down the voltage, but also provides substantial current limiting impedance. High reactance transformers, therefore, are commonly used for operating arc discharge devices, such as fluorescent lamps, since they provide the requisite high voltage for breaking down or starting the lamp, and subsequently limit the lamp current to safe values. When thus used, high reactance transformers are generally referred to as ballasts.

Reactors and transformers are provided with a core formed of magnetic material, such as iron, with one or more coils arranged thereon, the core providing a path for the mutual flux which links the coils. High reactance transformers are further provided with a separate magnetic path of the leakage flux, i. e., the flux produced by the load current flowing in the secondary winding. The path for leakage flux may be a shunt formed of magnetic material, frequently integral with the remainder of the core, or may be provided by suitable arrangement of the coils on the core.

In the past, the cores of small reactors and transformers, and more particularly the cores of high reactance transformers for operating arc discharge devices, have generally been formed from a stack of relatively thin laminations of magnetic material. In such constructions, each lamination is punched from a thin sheet of magnetic material, thus resulting in a substantial waste of material and accompanying increase in overall cost of the device. While various methods, such as the design of laminations which can be nested during the punching operation, have reduced the waste to some extent, it is obvious that there is some inherent waste in providing cores formed of punched laminations.

In order to reduce the amount of magnetic material required for reactors and transformers, including high reactance transformers, wound cores have been utilized with varying degrees of success. A wound core, instead of being built up of a stack of punched laminations, is wound up from a narrow strip of relatively thin magnetic material. This has, however, required that the core be cut into two sections in order to assemble the coil or coils thereon, thus necessitating the provision of means to clamp the core sections together. In addition, while wound cores have been successfully used for small reactors, the problem of providing magnetic shunts and of avoiding the transfer of flux between core elements at right angles to the plane of the laminations or layers thereof has until this time virtually precluded their economical use in high reactance transformers. Furthermore, it has not been possible to provide the necessary series and shunt airgaps without cutting the wound cores.

It is therefore desirable to provide an inductive device utilizing a wound core in which the wound core does not have to be cut in order to assemble the coils thereon. It is also desirable to provide a high rea-ctance transformer construction utilizing wound cores, which construction incorporates the necessary magnetic shunts and series airgaps without requiring that any of the wound cores be cut, and without requiring the transfer of flux from one core element to another at right angles to the plane of the laminations or layers thereof. It is further desirable that these devices be simple, readily assembled, and provide optimum utilization of material.

It is therefore an object of this invention to provide an improved inductive device incorporating the desirable features set forth above.

Another object of this invention is to provide an improved high reactance transformer incorporating the desirable features set forth above.

Further objects and advantages of this invention will become apparent by reference to the following description and the accompanying drawing, and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

This invention, in its broadest aspects, provides an inductive device having an elongated laminated core member with at least one coil positioned thereon and spaced from the end portions thereof. A wound core is provided embracing a side of the coil on one laminated side of the elongated core member with the laminated edges of its ends respectively completing magnetic circuits with the laminated side of the elongated core member end portions. Another wound core may be similarly arranged on the other laminated side of the elongated core member. With this construction, the elongated core member may be formed of a stack of relatively thin laminations of magnetic material, each lamination being cut from a narrow strip of such material thus involving minimum waste of material. In the alternative, the elongated core member may be formed from a wound core which is compressed into the elongated configuration. The yoke portion of the core which provides the complete magnetic circuit, i. e., a return path for the flux, is formed of a wound core laid on the side of the elongated core member and embracing a side of the coil thus eliminating the need for cutting the wound core. The laminated edges of the ends of the wound core complete the magnetic circuit with the laminated side of the elongated core member end portions thus providing for transfer of flux from one member to the other in a plane parallel to the laminations or layers of the core members and not at right angles to the laminations or layers of one of them. If desired, an airgap may be provided in the magnetic circuit by merely spacing one end portion of the elongated core member from the adjacent end of the wound core, thus again eliminating any need for cutting the wound core.

In a high reactance transformer, this invention contemplates at least a pair of spaced-apart coils on the elongated core member with .a wound core embracing one side of each coil on one side of the elongated core member. These wound cores provide a path for the leakage flux, the adjacent ends thereof forming a shunt with the elongated core member. With this construction, adjacent ends of the wound core may be spaced from the elongated core member to provide a shunt gap. A third wound core embraces one side of both coils and has the laminated edges of its ends completing the magnetic circuit with the laminated side of the elongated core member end portions, thereby providing a path for the mutual flux which 3 links both coils. Here, the wound core yoke portions provide both leakage and mutual flux paths and the requisite airga-ps without the necessity for cutting any of the wound coils.

In the drawings,

Fig. l is a view in perspective, partly broken away, showing a high reactance transformer constructed in accordance with the preferred embodiment of this invention;

Fig. 2 is an end view, partly broken away and partly in cross section, of the transformer of Fig. 1;

Fig. 3 is a side view, partly broken away and partly in section, further showing the improved transformer of Fig. 1 and showing one means of providingthe requisite airgaps;

Fig. 4 is a side view, partly in cross section, of a high reactance transformer constructed in accordance with Fig. 1 having another means for providing the airgaps;

Fig. 5 is an end view, partly broken away'andpartly in cross section, showing the transformer of Fig. 4;

Fig. 6 is a top view of a transformer constructed in accordance with another embodiment of this invention;

Fig. 7 is an end view, partly broken away and partly in cross section, of the transformer of Fig. 6;

Fig. 8 is a view in perspective, partly broken away showing a high reactance transformer constructed in' accordance with a further embodiment of this invention;

Fig. 9 is an end view, partly broken'away and partly in cross section, showing the transformer of Fig. 9; and

Fig. lOis a view in perspective of a wound core compressedinto an elongated configuration which may be used alternatively with the laminated elongated core members of Figs.'1 to 10 inclusive.

Referring now to'Figs. l, 2 and 3, there is shown a high reactance transformer, generally identified as 1, having an elongated core member Zformed of a stack of relatively thin laminations 3 of magnetic material. Laminations 3 may be cut from 'a'narrow strip of relatively thin magnetic material thus substantially eliminating all waste. in the alternative, the elongated core member 2 may be formed from a wound core 4 compressed in the requisite elongated configuration as shown in Fig. 10. Wound core 4 is formed by winding up a strip 5 of relatively thin magnetic material into a coil. A pair of spaced-apart coils 6- and 7 are arranged on the elongated member 2 and respectively spaced from the end portions 8 and 9. Coil 6 may, for example, be the primary winding for transformer 1 and coil 7 would thus be the secondary winding therefore.

In order to complete the magnetic circuit for elongated core member 2, the arrangement now to be described is provided. A pair of yoke wound

core members

10 and 11, each formed from a wound strip of relatively thin magnetic material, is provided respectively embracing opposite sides of coil 7 on opposite laminated sides 14 and of the elongated core member 2. Another pair of yoke wound core members 16 and 17 are similarly arranged embracing opposite sides of coil 6 on opposite laminated sides 14- and 15 of the elongated core member 2.. Ends 18 and 19 of yoke wound

core members

10 and 16 respectively, and and 21 of yoke core members 11 and 17 respectively, are respectively abutting and have their laminated edges completing a magnetic circuit with the laminated

sides

14 and 15 of the elongated core member 2. Ends 18 and 19 of yoke wound

core members

19 and 16 respectively and 2d and 21 of yoke wound core members 11 and 17 respectively thus form magnetic shunts for the high reactance transformer 11.

The requisite shunt airgaps are provided in this case by means of an insulating tape 26 surrounding the elongated core member 2,

intermediate coils

6 and 7 thereby spacing the

adjacent ends

18 and 19 of yoke

wound core members

10 and 16 respectively and 20 and 21 of yoke wound core members 11 and 17 respectively from laminated

sides

14 and 15 of elongated core member 2. Ends 22 and 23 of yoke wound core members 16 and 17 have their laminated edges respectively completing a magnetic circuit with the laminated sides 14- and 15 of end portion 9 of elongated core member 2 by direct engagement therewith, as seen in Fig. 3.

Ends

2 and 25 of yoke wound core members 14) and 11 have their laminated edges respectively completing a magnetic circuit with the laminated sides 14- and 15 of end portion 3 of the elongated core member 2, with insulating tape 26 forming a series airgap, as shown in Fig. 3. Yoke wound core members 11), 11, 16 and 1'7 provide a path for leakage flux and also form magnetic shunts with the elongated core member 2.

A third pair of yoke wound

core members

27 and 28, are provided yoke, wound core member 27 being arranged in the same plane as yoke wound

core members

10 and 16 and embracing the same, while yoke wound core member 28 is arranged in the same plane as yoke wound core members 11 and 17 and embraces the same. Ends 29 and 30 of yoke wound

core members

27 and 28 have their laminated edges respectively completing magnetic circuits with laminated sides 1 -1 and 15 of end portion 9 of clon gated member 2 by direct engagement, as shown in Fig. 3, while ends 31 and 32 of yoke wound

core members

27 and 28 have their laminated edges respectively completing magnetic circuits with the

laminated sides

14 and 15 of end portion 8 of the elongated core member 2. Here again, insulating strip 26 forms a series airgap between ends 31 and 32 of

yoke core members

27 and 28 and end portion 8 of elongated core member 2. Yoke wound core members 27 and 23 form the flux path for the mutual flux which links both coils 6 and '7.

It will now be readily seen that the improved high reactance transformer construction of Figs. 1, 2 and 3 is accomplished with minimum waste of core material and that wound cores provide paths for both the leakage flux and mutual flux. It will also be seen that the flux paths and also the requisite airgaps are provided Without the necessity for cutting any of the wound cores.

Referring now to Figs. 4 and 5 in which like elements are indicated by like reference numerals, it will be seen that

notches

33 and 34 are formed in

laminated sides

14 and 15 of elongated core member 2 thereby defining bridged shunt airgaps with ends 13 and 19 of yoke wound

core members

10 and 16 respectively and with

ends

20 and 21 of yoke wound core members 11 and 17 respectively. Similarly, notches 35 and 36 are cut in

laminated sides

14 and 15 of end portion 8 of elongated core member 2 thereby forming bridged series airgaps with ends 24 and 25 of yoke wound

core members

16 and 11 respectively and ends 31 and 32 of yoke wound

core members

27 and 28 respectively. There is thus provided an alternative method of obtaining the requisite series and shunt airgaps.

Referring now to Figs. 6 and 7, in which like elements are indicated by like reference numerals, there is shown a transformer, generally identified as 37, having an elongated core member 2 formed of a stack of relatively thin laminations 3 of magnetic material. Spaced-

apart coils

6 and 7 are positioned on elongated core member 2 and respectively spaced from the end portions 8 and 9 thereof. Here, the yoke wound core members providing paths for the leakage flux are eliminated and a pair of yoke wound

core members

38 and 39 respectively embrace the sides of both

coils

6 and 7 on either

laminated sides

14 and 15 of elongated core member 2. Here, the ends 40 and 41 of yoke wound

core members

38 and 39 respectively have their laminated edges respectively completing mag netic circuits with the laminated sides of end portions 8 and 9 of elongated core member 2 by direct engagement therewith.

Referring now to Figs. 8 and 9, in which like elements are again indicated by like reference numerals, there is shown a high reactance transformer, generally identified as .42 having an elongated core member formed of a stack of relatively thin laminations 4d of magnetic material. In this embodiment, a wound core member 45 is arranged around elongated core member 43 with its general plane at right angles to the planes of the laminations 44 of elongated core member 43. Spaced-

apart coils

6 and 7 are arranged on elongated core member 43 and wound core member 45 and are spaced respectively from the end portions thereof.

In order to accommodate the mutual flux which links the

coils

6 and 7, a pair of yoke wound

core members

46 and 47 are provided respectively embracing the sides of both

coils

6 and 7 and either side of wound core member 45. Here, the laminated edges of the ends 48 and 49 of yoke wound

core member

46 and 50 and 51 of yoke core member 47 respectively complete magnetic circuits with the laminated edges of the ends of wound core member 45 (only end 52 appearing in Figs. 9 and If desired, a series airgap may be provided between ends 48 and 50 of yoke wound

core members

46 and 47 respectively and end 52 of wound core member 45 by merely inserting a strip of insulating material therebetween as shown in Fig. 3, or by providing a notch as shown in Fig. 4.

In order to provide a path for the leakage flux, a pair of yoke wound

core members

53 and 54 are arranged embracing either side of coil 7 and with the laminated edges of their

sides

55 and 56 and 57 and 58 respectively engaging the laminated edges of

sides

59 and 60 and 61 and 62 of yoke wound

core members

46 and 47 respectively. Another pair of yoke wound

core members

63 and 64 are similarly arranged on either side of coil 6 with the laminated edges of their

sides

65 and 66 and 67 (the side of yoke wound core member 64 opposite from side 67 not being shown in Fig. 9) respectively engaging the laminated edges of

sides

59 and 60 and 61 and 62 of yoke wound core members 47 and 48 respectively. Here, adjacent ends 68 and 69 of yoke

Wound core members

53 and 63, and adjacent ends 70 and 71 of adjacent yoke

Wound core members

54 and 64 are respectively abutting thereby defining magnetic shunts for the high reactance transformer 42. In addition, the laminated edges of ends 72 and 73 of yoke wound

core members

53 and 63 and the laminated edges of ends 74 and 75 of yoke wound

core members

54 and 64 respectively complete magnetic circuits with the laminated sides of the end portions of elongated core member 44. Here again, shunt airgaps between ends 68 and 69 of yoke wound

core members

53 and 63 and between ends 70 and 71 of yoke wound

core members

54 and 64 may be defined by either of the means shown in Figs. 3 and 4, and series airgaps between ends 72 and 74 of yoke wound

core members

53 and 54 may be defined with the end portion of elongated core member 44 in like manner.

The embodiments of any of the above figures may conveniently be enclosed in a simple case assembly, as shown in Figs. 1, 2 and 3. Here, cap members 95 and 96 each having

indentations

97 and 98 to accommodate coils 6 and '7 respectively are arranged on either side of the device and

side enclosure members

99 and 100 extend between cap members 95 and 96 respectively and between end portions 8 and 9 of elongated core member 3 respectively, thus totally enclosing the core in coil assembly. The cap members 95 and 96 and

side enclosures

99 and 101 are held in assembled relation by means of

slots

100 and 102 respectively arranged on either side of the cap members 95 and 96 in which

Wedge portions

103 and 104 of

side enclosures

99 and 100 are arranged. An opening 105 may be formed in one of the side enclosures members to accommodate external leads 106. Openings 107 may be formed in cap member 95 to provide for the mounting of the device.

While this invention has been described in connection with high reactance transformers, it will be readily apparent that it is equally applicable to low reactance transformers and reactors. In addition, While Figs. 1 to 10 inclusive show transformers having two coils, it will also be readily apparent that this invention is equally applicable to close coupled transformers having more than one winding arranged on the same coil, or to other types of transformers having more than two coils. It will be readily seen that the enclosing case of Figs. 1, 2 and 3 may be filled with the conventional potting compound if desired. As is pointed out above, it will also be readily apparent that the compressed wound core member 4 of Fig. 10 may be substituted for the laminated elongated core member of any of the figures.

It will now be clearly seen that this invention provides an improved inductive device having a core assembly fabricated with a minimum waste of magnetic material. This invention utilizes wound cores with no cutting of the wound cores required to either assemble them on the coils or to provide the requisite airgaps. In addition, the transfer of flux is effected between difierent core elements without requiring the flux to pass at right angles to the plane of the laminations or layers of one element. It will further be seen that the resultant device is charac terized by its simplicity, ease of assembly, and resultant reduction in over all cost. understood that by virtue of this simplicity, devices constructed in accordance with this invention lend themselves readily to manufacture on automatic machinery.

While I have shown and described particular embodi ments of this invention, further modifications and improvements will occur to those skilled in the art. I desire that it be understood therefore that this invention is not limited to the particular forms shown and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of this invention.

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

1. A high reactance transformer comprising an elongated laminated core member formed of magnetic material, at least two spaced-apart coils positioned on said elongated cc-re member and respectively spaced from the end portions thereof, a first yoke core member formed from a wound strip of magnetic material encircling a side of one of said coils on one side of said elongated core member, a second yoke core member formed from a wound strip of magnetic material encircling a side of another of said coils on said one side of said elongated core member, the adjacent ends of said first and second yoke core members forming a magnetic shunt for said transformer and a third yoke core member formed from a wound strip of magnetic material encircling one side 7 of both of said coils, said third yoke core member being positioned on one laminated side of said elongated core member with the laminated edges of its ends respectively completing a magnetic circuit with said laminated side of said elongated core member end portions.

2. A high reactance transformer comprising an elongated laminated core member formed of magnetic material, at least two spaced-apart coils positioned on said elongated core member and respectively spaced from the end portions thereof, a first pair of yoke core members each formed from a wound strip of magnetic material respectively encircling opposite sides of one of said coils on opposite sides of said elongated core member, a second pair of yoke core members each formed from a wound strip of magnetic material respectively encircling opposite sides of another of said coils on said opposite sides of said elongated core member, the adjacent ends of said yoke core members respectively forming magnetic shunts for said transformer, and a third pair of yoke core members each formed of a wound strip of magnetic material respectively surrounding opposite sides of both of said coils on opposite laminated sides of said elongated core member, said third pair of yoke core members having the laminated edges of their ends respectively com:

It will further be readily 7 pleting magnetic circuits with said laminated sides of said elongated core member end portions.

31 A high reactance transformer comprising an elongated laminated core member formed of magnetic material, at least two spaced-apart coils positioned on said elongated core member and respectively spaced from the end portions thereof, a first yoke core member formed from a wound strip of magnetic material encircling a side of one of said coils on one side of said elongated core member, a second yoke core member formed from a wound strip of magnetic material encircling a side of another of said coils on said one side of said elongated core member, the adjacent ends of said first and second yoke members forming a magnetic shiint for said transformer, and a third yoke core member-"formed from a wound strip of magnetic material embracing said first and second yok'e core members, said third yoke core member'b'eing'positioned onene laminated side of said elongated core member with'the laminatededges of its ends respectively completing a magnetic circuit with said laminated side of said elongated core member end portions.

4. A high reactance' transformer comprising an elongated laminated core member formed of magnetic material, at least two'spa'ced-apart coils positioned on said elongated core member and respectively spaced from the end portions thereof, a first yoke core member formed from a wound strip of magnetic material encircling a side of one of said coils on one side of said elongated core member, a second yoke core member formed from a wound strip of magnetic material encircling a side of another of said coils on said one side of said elongated core member, the adjacent ends of said first and second yoke core members forming a magnetic shunt for said transformers, a third yoke core member formed from a wound strip of magnetic material encircling one side of both of said coils, said third yoke core member being positioned on one laminated side of said elongated core member with the laminated edges of its ends respectively completing a magnetic circuit with said laminated sides of said elongated core member end portions, and means insulating said adjacent ends of said first and second yoke core members from said elongated core member thereby defining a shunt airgap.

5. A high reactance transformer comprising an elongated laminated core member formed of magnetic material, at least two spaced-apart coils positioned on said elongated core member and respectively spaced from the end'portions thereof, a first yoke core member formed from a wound strip of magnetic material encircling a side of one of said coils on one side of said elongated core member, a second yoke core member formed from a wound strip of magnetic material encircling a side of another of said coils on said one side of said elongated coremember, the adjacent ends of said first and second yoke core members forming a magnetic shunt for said transformer, and a third yoke core member formed from a wound strip of magnetic material encircling one side of both of said coils, said third yoke core member being positioned on one laminated side of said elongated core member with the laminated edges of its ends respectively completing a magnetic circuit with said laminated side of said elongated core member end portions, said laminated side of said elongated core member having a notch formed therein defining a bridged shunt airgap with said adjacent ends of said first and second yoke core members.

6. A high reactance transformer comprising an elongated laminated core member formed of magnetic material, at least two spaced-apart coils positioned on said elongated core member and respectively spaced from the end portions thereof, a first yoke core member formed from a wound strip of magnetic material encircling a side of one of said coils on one side of said elongated core member, a second yoke core member formed from a wound strip of magnetic material surrounding a side" of another of said coils on said one'si'de'of said elongated core member, the adjacent'ends" of the said first and second yoke core members forming a magnetic shunt for said transformers, and'a thir'd yoke core meritber formed rrem'a wound strip of magnetiornaterial surrounding one side of both of said coils, said third yoke core member beingpo'sitioned on one laminated side of said elongated core member with the laminated edges of its ends respectively completing'a magnetic circuit with said laminated sides of said elongated core member end portions, said adjacent ends of said'fir st and second yoke core members defining a shiint airgap with said elongated core member.

7. A high reactance transformer comprising'an elon gated laminated core'meinbe'r'form'ed of magnetic material, at least two spaced-apart coils positioned on said elongated core member and respectively spaced from the end portions thereof, a first pair of yoke core members each formed' from a woundstr'ip of magnetic material respectivelysurrounding 'opposite sides of one of said coils on opposite sides of said elongated core member, a second pairof yoke core members each'formed from a wound strip of magnetic material respectively surrounding opposite sides of another of said coils on said opposite sides'of said elongated core member, the adjacent ends of saidyoke core members respectively forming magnetic shunts" for'saidtrans'former, and a third pair of yoke'core'members each formed of a wound strip of magnetic material respectively embracing said first and second pair of yoke 'core memberson opposite laminated sides 'of "said elongated core member, said third pair of yoke core 'membershaving the laminated edges of their .ends respectivelyrornpleting magnetic circuits with said laminatedsidesof" said 'elongated core member end portions'l" 8. A"high"rea'ctance transformer comprising an elongated'laminated' core member formed of magnetic material, at'least two sp'aced a'part coils positioned on said elongatedcore member and respectively spaced from the end portions thereof, afirst yoke core member formed from a wound strip'of magnetic material encircling one side of one of said coils on one laminated side of said elongated core member and completing a magnetic circuit therewith, a second yoke core member formed from a wound strip of magnetic material encircling one side of another of said coils on said one laminated side of said elongated core member and completing a magnetic circuit therewith, the adjacent ends of said first and second yoke core members abutting and forming a magnetic shunt for said transformer, and a third yoke core member formed from a wound strip of magnetic material arranged in the same plane as said first and second yoke core members and embracing the same, said third yoke core member having the laminated edges of its ends respectively completing a magnetic circuit with said one laminated side of said elongated core member end portions.

9. A high reactance transformer comprising an elongated laminated core member formed of magnetic material, at least two spaced-apart coils positioned on said elongated'core member and respectively spaced from the end portions thereof, a first pair of yoke core members each formed from a wound strip of magnetic material respectively encircling opposite sides of one of said coils on either laminated side of said elongated core member and completing a magnetic circuit therewith, a second pair of yoke core members each formed from a wound strip of magnetic material respectively encircling opposite sides of another of said coils on either laminated side of said elongated core member and completing a magnetic circuit therewith, the adjacent ends of said first and second yoke core members being respectively abutting and formingmagnetic shunts for said transformer, and a third pair of yoke core members each formed from a wound strip of magnetic material respectively arranged in the same plane as said first and second pair of yoke core members and respectively embracing the same, said third pair of yoke core members respectively having the laminated edges of their ends respectively completing magnetic circuits with said laminated sides of said elongated core member end portions.

10. A high reactance transformer comprising an elongated laminated core member formed of magnetic material, a first yoke core member formed from a wound strip of magnetic material embracing said elongated core member in a plane at right angles to the plane of the laminations thereof, at least two spaced-apart coils positioned on said elongated core member and said first yoke core member and respectively spaced from the end portions thereof, a second yoke core member formed from a wound strip of magnetic material embracing one side of both of said coils and having one laminated edge of its ends respectively completing a magnetic circuit with one laminated edge of the ends of said first yoke core member, a third yoke core member formed from a wound strip of magnetic material encircling said one side of one of said coils and having one laminated edge of its sides respectively engaging the other laminated edge of the sides of said second yoke core member, and a fourth yoke core member formed from a wound strip of magnetic material encircling one side of another of said coils and having one laminated edge of its sides respectively engaging the other laminated edge of the sides of said second yoke core member, the adjacent ends of said third and fourth yoke core members being abutting and forming a magnetic shunt for said transformer, said adjacent ends of said third and fourth yoke core members having their said one laminated edges thereof respectively completing a magnetic circuit with one laminated side of said elongated core member, the outer ends of said third and fourth yoke core members having their said one laminated edges respectively completing a magnetic circuit with said one laminated side of said elongated core member end portions.

11. A high reactance transformer comprising an elongated laminated core member formed of magnetic material, a first yoke core member formed from a wound strip of magnetic material embracing said elongated core member in a plane at right angles to the planes of the laminations thereof, at least two spaced-apart coils positioned on said elongated core member and said first yoke core member and respectively spaced from the end portions thereof, a first pair of yoke core members each formed from a wound strip of magnetic material respectively embracing opposite sides of both of said coils and respectively having one laminated edge of their ends respectively completing magnetic circuits with the laminated edges of the ends of said first yoke core member, a second pair of yoke core members each formed from a wound strip of magnetic material respectively encircling said opposite sides of one of said coils and respectively having one laminated edge of their sides respectively engaging the other laminated edges of the sides of said first yoke core member, and a third pair of yoke core members each formed from a wound strip of magnetic material respectively encircling said opposite sides of another of said coils and respectively having one laminated edge of their sides respectively engaging the other laminated edge of the sides of said first pair of yoke core members, the adjacent ends of said second and third pair of yoke core members being respectively abutting and forming magnetic shunts for said transformer, said adjacent ends of said second and third pair of yoke core members having their said one laminated edges thereof respectively completing magnetic circuits with the laminated sides of said elongated core member, the outer ends of said second and third pair of yoke core members having their said one laminated edges respectively completing magnetic circuits with said laminated sides of said elongated core member end portions.

Great Britain Jan. 17, 1891 Great Britain July 1, 1943