US2690536A - Saturable magnetic device - Google Patents

Description

Se t. 28, 1954 R. G. ADAMS, JR

SATURABLE MAGNETIC DEVICE Filed March 1, 1952 FIG, 2

FIG. 1

FIG. 3

FIG. 4

INVENTOR, RALPH G. ADAMSJQ' FITTUK/VE) Patented Sept. 28, 1954 UNITED STATES TENT OFFICE to Bendix Aviation Corporation,

Teterboro,

N. J a corporation of Delaware Application March 1, 1952, Serial No. 274,413

4 Claims. (Cl. 323.89.)

The present invention relates to saturable magnetic devices andmore particularly to saturable magnetic devices wherein a single direct current conductor serves as the direct current winding of the device.

U. 8. application Serial No. 238,420, filed July 25, 1951, by Paul W. Franklin, discloses a saturable magnetic device used as a means. of current controlfor. a D. C. generator. The current carrying conductor passes through the center of the toroid and is symmetrical on both sides. The leakage fiux set up by the current in the conductor passes uniformly through the core of the toroid. However, in a practical application, it was necessary to form the current carrying conductor in a U- shape to loop through the toroid. It was found that when the aforenoted configuration was used, the leakage flux was concentrated in one spot in the core of the toroid. Such a concentration of the leakage fiux causes uneven distribution of the flux in the core and upsets the tap ratio of the windings.

In order to overcome the aforenoted difficulty, the present invention provides magnetic shields between the sides of the toroid and the conductors.

An object of the present invention is to provide novel means for shielding a saturable magnetic device against leakage flux.

Another object of the invention is to provide novel and improved means for sensing the magnitude of a direct current.

Another object of the invention is to provide novel means for shielding a toroid having an unsymmetircal conductor passing therein.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one embodiment of the invention is illustrated by way of example.

In the drawing:

Figure 1 is a schematic diagram of a system embodying the invention.

Figure 2 is a sectional view of a toroid in which the conductor is symmetrical.

Figure 3 is a sectional view of a toroid and an unsymmetrical conductor.

Figure 4 is a sectional view of a toroid and an unsymmetrical conductor with shielding.

Referring now to Figure 1, the numeral 5 represents a direct current conductor in which it is desired to sense the magnitude of the current flowing therein. The conductor 5 has a U-shaped portion 5 having legs I and 8. The U-shaped portion 6 passes through a magnetic core 9 on which are wound a multi-tapped primary Winding Hi and a feed back winding H. One end of the winding it is connected by conductor E2 to one terminal or" a suitable A. C. source (not shown); Taps 53A, I33, E30 and MD of the winding [flare arranged for cooperation with a switch arm it. The switch arm Hi is connected by conductor E5, rectifier i6 and conductor ll to one end of the. winding H. The other end of the winding li is connected by a conductor it to one side of a suitable load it. The other side of the load it is connected by a conductor 20 to the other side of the A. C. source. A capacitor 25 is connected in parallel with the winding H and load I9.

While the load It has been shown diagrammatically, it is understood that it may be any suitable load, such as, for example, a control coil for a carbon pile regulator, an indicating instrument or the like.

Shields 22 and 23 of magnetic material are inserted along the respective legs i and 8 between the conducto 5 and the core 9.

Referring now to Figures 2, 3 and 4 for an explanation of the invention, wherein corresponding parts have been assigned the same reference numerals in the various figures. In Figure 2, the conductor 5 passes through the center of the toroid 9 and the leakage flux set up by the current in the conductor 5 passes uniformly through the toroid 9. Hence, it can be seen that no shielding will be necessary.

Many installations are not adapted to use the configuration of Figure 2 and it is necessary to loop the conductor 5 through the core F3 as shown in Figure 2. With this arrangement, however, it is apparent that the leakage flux will be concentrated in one spot on the core 9, the concentration taking place in the section of the core directly inside the U-shaped section 6 of the conductor 5. This uneven distribution of the leakage flux upsets the tap ratio on the winding it By installing shields 22 and 23 of magnetic material as shown in Figure 3, the leakage flux flows from the conductor 5 and is prevented from reaching the core 9 adjacent to the legs I and 8 by the shields 22 and 23. The shields are of a thickness such that they will not saturate under the magnetic flux. Further, the air gap between the shields also tends to prevent saturation. In other words, the leakage flux is diverted by the magnetic material and rather than take air paths through the core, it now flows along the shields and back around the conductor.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangement of the parts, which will now appear to those skilled in the art, may be made without departing from the scope of the invention.

What is claimed is:

1. A saturable magnetic device having a ring like core of magnetic material, a multi-tapped winding wound on a portion of said ring, a second winding looped through said core, a source of alternating current connected to said first winding, a source of direct current connected to said second winding, and magnetic shields positioned between said core and the sides of the loop of said second winding.

2. A saturable magnetic device having a toroid core of magnetic material, a multi-tapped primary winding wound on said core, means including a source of alternating current for energizing said primary winding, a U-shaped direct current winding having the bottom of the U through the center of said toroid, means including a source of direct current for energizing said direct current winding, and shields of magnetic mateial positioned between the legs of the U and the toroid to provide a shield for leakage flux.

3. A saturable reactor having a toroid core of magnetic material, a primary winding wound on said core, a source of alternating current connected to said primary winding, a direct current winding passing through the center and partially around said core, a source of direct current connected to said direct current winding, and magnetic shields positioned between said core and the portion of said direct current winding passing partially around said core.

4. A saturable magnetic device having a core of magnetic material having an opening therein, a primary winding, means including a source of alternating current for energizing said primary winding, a direct current winding passing through said opening and having a portion crossing said core, means including a source of direct current for energizing said direct current winding; the improvement comprising shields of magnetic material positioned between said core and the portion of the direct current winding crossing said core.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 783,533 Moody Feb. 28, 1905 1,130,260 Dann Mar. 2, 1915 2,340,081 Sauer Jan. 25, 1944 2,388,848 Howe NOV. 13, 1945 2,567,744 Stanton Sept. 11, 1951

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