US1231875A - Magnetic choking device. - Google Patents

Description

H. H. & W. GIFFOHD.

MAGNETIC CHOKING DEVICE.

APPLICATION mw JUNE 10. me.

m u 7 z J P f 6/ M z w w. w C 2 G Y\ c 0 0 2a a d 7 d. /V/W/// Md 1., 1 u a- J 32 W 6 7 .w w 7/// c 1 J j Attorneys ED STATES PATENT OFFICE.

HIRAM H. G'IFFORD AND WILLIAM GIFFORD, OF TRAVERSE CITY, MICHIGAN.

MAGNETIC CHOKING DEVICE.

Y '0 all whom 'it may concern Be it known that we, HIRAM H. Grrronn and 'WIILIAM G rronn, citizens ofthe United States, residing at Traverse City, in the county of Grand Traverse, State of Michigan, have invented a new and useful MagneticGhokin Device, of which the followin 'is aspeci cation.

'- he present invention appertains to chok- -ing devices such as are used in electrical conductors, and aims to provide a novel and improved yet-simple and inexpensive magnetic choking'device for use in electric service and transmission lines in conjunction with ordinary lightning arr-esters for the protection of a transformer or other electrical equipment against damage by lightning.

It is the'object of'the invention to provide a magnetic choking device which will arrest or retard "the instantaneous rush -or surge of electricalcurrent past the choking device to the electrical apparatus, as when the conductor is charged by a stroke of lightning or other' high frequency electrical disturbance of similar nature, whereby "to protect the electrical apparatus and to give the lightning arr-ester suilicient opportunity to act before the high frequency current can pass the choking device.

With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed can be made within thescope of what is claimed without departing from the spirit of the invention.

The invention is illustrated inthe'accompanying drawing, wherein Figure '1 is a longitudinal section of one form of the choking device, portions being shown in elevation.

Fig.2 is a similar view of another form.

Fig. 3 is an elevation of a third form of the invention, portions being broken away and shown in section.

Fig. t is a view similar to Fig. 3 of another variation.

Specification of Letters Patent.

Patented Julyfi, 191-7.

Application filed June 10, 1916. Serial No. 102,989.

longitudinal bore or recess 2 extending from one end -'to a point adjacent the other end, there being a reduced aperture 3 extending from the last mentioned end of the body to the bore Threadedly or otherwise engaged within the aperture dis a bushin 4 of insulating material, which is provi ed with a convexed hood 5 for shedding rain and moisture to the sides 'of the body, the present device being adapted especially for use in a vertical position with "the bushing 4 at the upper end of the body. Another bushing or plug=6 of insulating material is thre a dedl-y or =othcr-wise engaged within the lower end otthe bore 2, and has'an enlargement 7 resting against the lower end ofthe body 1. As a convenient means *for sup porting the body 1 one side thereof can be formed or provided with an outstanding screw 8 to be threaded into the cross arm ofthe pole which supports the conductors, although the body l'can be supported in any suitable manner. The bushings 4 and 6 are apertured for-the passage of the conductor 9 'therethrough, and said conductor has a coil or helix 10 within the bore 2 between the bushing or plug 6 and the shouldered end of the bore 2, said conductor being insulated to insulate it from the 'body 1.

In practice, the choking device is interposed in the conductor between the lightning arrester and electrical equipment (not shown) to be protected, and should the con ductor 9 be struck by lightning or otherwise subjected to a high frequency electrical disturbance of similar nature, the choking device will retard or check the flow of current to'the electrical apparatus, thus protecting it from injury in connection with the lightning arr-ester. The lightning arrester is thus given an opportunity to act in order to prevent the abnormally high voltage-current from passing to the electrical equipment. An ordinary current will flow along the conductor past the body 1 without difiiculty w'herethenumber of turns of the helix are of proper ratio to the amountof current flowing through the conductor, but with lightning or similar electrical disturbance, the conditions are reversed. Lightning or equivalent high frequency electrical current will leave a complete metallic path of low ohmic resistance and jump an air gap that a normal line current would not, rather than pass the mag netic choking device. This is due to the high self induction set up in the magnetic choke device by currents of a highly oscillatory character, such as produced by lightning. The conductor in extending past the iron or steel body 1 provides the choking effect due to the fact that a high frequency current will set up magnetic fields in the body 1 which resist the flow of the high frequency current.

The device can be used wherever necessary, and while applicable to indoor installations, is especially adapted for out door service, to protect out door transformer installations, meters, etc. The surface of the body 1 and insulating bushings can be coated by enamel or other material whereby to protectthe device from the elements. The device can be constructed in different sizes and proportions for currents of different voltage, and is adapted to supersede the more expensive and less efiicient choke coils now in use for the service that the present choke device is designed. The present device is thoroughly eflicacious in use, is easily installed, is non-destructible, and is cheaper and superior in many respects over choke coils which are commonly used. The body 1 is of such formation and is associated with the conductor in such a way that in the presence of a high frequency current, the magnetic field is set up in the body proportionateto the flow of current, and this consumes a sufficient period of time during which the .potential builds up, between the magnetic choke device and conductor to a point sufficiently high, to cause the lightning arrester to discharge and carry the current to ground. In so doing, the apparatus protected is relieved from the great strain it would otherwise be subjected to, and the danger of a break down is greatly lemened. The body 1 also protects the helix 10. The interior as well as the exterior of the device can be coated by enamel, or the like, to insulate and render the device weather proof.

The device shown in Fig. 2 is of slightly different formation than that shown in Fig. 1,. This second form of the device is of the hour glass type, the iron or steel body 1 having the hour glass bore 2* which is of a constricted diameter between its ends and which increases in diameter toward the ends of the body 1. This device, the same as that shown in Fig. 1, is adapted for use in a vertical position, although it-can be used in a horizontal or other position. -A bushing 4 of insulating material is threaded or otherwise engaged within'the upper end of the body 1 and is provided with a convexed portion. 5 for shedding rain, and the like. A bushing or plug 6 of insulating material is threadedly or otherwise engaged within the lower end of the body 1 and has an enlarged portion 7 bearing against the lower end of the body. ,The bushings 4 and .1

(1 are aperturcd for the passage of the conductor 9, which is provided with a hour glass type of coil 10fitting snugly within the bore 2. The exterior of the body 1 is also preferably shaped as seen in Fig. 2, in preference to the shape of the body 1. The body and bushings can be enameled exteriorly and interiorly to protect them from the elements, and due to the use of the hour glass coil 10, the device is particularly efficient for its intended purpose.

The device shown in Fig. 3 has an external instead of an internal coil as used in the devices shown in Figs. 1 and 2.

The device in Fig. 3 has a body 1" of ovoid form, and provided with a 10m 'tudinal bore 2 extending therethroug and through which a bushing 4" of insulating material extends, said bushin being tubular for the reception of the con uctor 9". The body 1 is provided with a helical groove 11 in its periphery or circumference,.the

axis of said groove being coincident with the axis of the body, and the body has radial bores 12 extendin from the ends of the groove 11 to the ushing 4" through which the conductor 9" extends, and said conductor has a coil or helix 10 seated within the groove 11". The groove 11" is preferably filled with insulating cement or equivalent material 13, and the surface of the body and bushing are preferably enameled or similarly finished.

Figs. 4 and 5 illustrate a squirrel cage type of choking device, embodying the body 1 of iron or steel, and provided with a lon gitudinal bore 2 through which the insulated bushings 4 extends, the conductor 9 extending straight through the bushings 4. The body 1 is provided upon its exterior with longitudinal grooves 11 and with annular grooves 11 at the ends of the grooves 11, and .longitudinal strips 10 are seated within thegrooves 11 and have their ends secured to rings 10 lying within the grooves 11, to provide the squirrel cage. The grooves 11'' and 11 are filled with insulating cement 13 and the device is coated with enamel or equivalent material to protect the same from the elements. It has been found that a high frequency current passes with great difficulty through this type of magnetic choking device.

The enamel and cement used provide for the insulation of the device as well as protecting it-from the elements.

Having thus described the invention, what is claimed as new is:

1. A ma etic choking device embodying a thick-wal ed tubular body of magnetic material, insulation therein projecting from its ends, a conductor extending into and out of said body through said projecting ortions of the insulator and provided therebetween with a coilinclosed by the body, to provide Choking effect to a high frequency current.

2. A magnetic choking device embodying a thick-wa1led tubular body of magnetic material having a helical groove in its periphery, insulating material Within said body projecting from the ends thereof, and a eon duetor extending into and out of the ends of the body through the projecting portions 10 of the insulating material and having a coil thercbetweeu seated in said groove and inelosed by the body.

In testimony that we claim the foregoing as our own, we have hereto allixed our signatures in the presence of two Witnesses.

HIE-AM H. GIFFORD. \VILLIAM GIFFORD.

\Vitnesses MINNIE (ls'iimi nicn ALMA D. THOMPSON.

Ccpies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents, Washington, I). C.

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