US1537353A - Electric switch - Google Patents

Description

May 12, 1925.

. 1,537,353 '-J. D. HlLLlARD ELECTRIC SWITCH Filed Feb, 8, 1921 s shets-sheet 1 Inventor: John' D. Hilliard,

Hisv Ylttvorne g.

May l2, 1925.

J. D. HILLIRD ELECTRIC SWITCH Filed Feb. 8, 1921 l l l l l r l l l l a l l f l l l l r l l f l l l Il l. lllllllllllllll 'a P. www@ @fm/7. M @D V H MIWM May 12, 1925.

J. D. HILLIARD ELECTRic swITcH Filed Feb` 8, 1921 3 Sheets-Sheet E, w mm u @QM VDfH .mf/M ..0

o Tu bij Patented M'ay 12, 1925.

UNrrED STATES 1,537,353 PMENT ogFlcE.

JOHN D. HILLIARD, F SCHENECTADY, NW YORK, ASSIGNOR TO ELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

ELECTRIC SWITCH.

Application* led February 8, 192.1. Serial No. 443,440.

To all whom t may concern.'

Be it known 'that I, JOHN D. HILLIARD, a

' citizen of the United States, residing at Schenectady, in the countyA of Schenectady, State of New York, have invented certain new and useful Improvements in Electric Switches, of which the following is a specification. l

This invention relates to electric switches and particularly to switches of that type in which the circuit is interrupted in an insulating liquid.

When opening high power circuits under oil the arc formed upon theseparation of the switch electrodes causes a certain amount of oil to be dissociated or volatilized, thus producing a large quantity of highly heated gas. lThe pressure produced may be sufficient to throw oil out of the oil tank and even to burst the tank itself. The o-il is thrown out of the oil tank in a more or less atomized condition and as it is often carbonized, formsa black deposit upon the surrounding objects. Following the oil is the highly heated gas which upon contact with the air may ignite and cause a secondary eX- plosion of more or less violence. The heated gas often ignites within the oil tank upon contact with the air above the surface of the oil, thereby causing explosions violent enough to burst the oil tank or tear it loose from its foundation. Even where the direct injury from the explosion is slight, the fire risk in the station is increased, and inarate the oil from the gas and allow only the latter to escape, or to prevent any flare-back of the burning gases to the interior of the oil tank, and tubes have been employed as vents cooled before coming into contact with the air. Although many of these devices have improved the operation of oil` switches, none of them, so far as applicant is aware, have made possible the opening of. the ve high powered circuits et present in use mth the tice.

stances have occurred where the explosionA within which the escaping products may bedegree of safety demanded in modern prac- According to my present invention I so construct the switch that when the circuit is broken under oil practically no oil is ejected from the oil tank and secondary explosions caused by contact'of heated gas with the air are prevented. To this end I interpose in the path of the fluids set in motion by the arc a means which will prevent the ejection of liquid from the tank, separate a large portion of the oil vapor and atomized oil from the gas and also cool the fluids ejected from the tank to a temperature below that at which the fluids spontaneously ignite upon contact with the air, or to a temperature such that they are no longer dangerous to the installation. These various effects are accomplished by causing the moving fluid to be broken up into a plurality of fine streams which are caused to flow through circuitous passages through cooling material. I preferably arrange these' passages in or to communicate with the upper part of the oil tank. The pressure created by the arc throws a certain quantity of liquid oil toward the ltop of the tank and into these passages, where its flow is impeded, so that the gases generated at the arc have an opportunity to rise within the tank and enter the passages before any great quantity of liquid has entered them, and thereby the separation of the oil and gas is facilitated. I find that by making the path taken by the streams of fluid circuitous rather than straight I am able to effect the desired condensation and reduction of temperature of the fluids with a comparatively small volume of cooling material.

While the specific embodiment of the means above described may take a variety of forms, I prefer to employ for this purpose a perforated baffle or barrier composed essentially of a mass of pebbles or small fragments, for example, gravel or similar material, so arranged that the projected fluids are forced through the gravel.

This application is a continuation in art of m application, Serial No. 332,621, led Octo er 23, 1919, electrical apparatus, and assigned to the assignee of the present application. In my prior application, I have disclosed the use of a gravel baffle in connection with fluid break electric switches.

The mdfld forms of my invention shown by Figs. 4, 5 and 6 are described and claimed specifically in my copending applications Ser. No. 602,703, 'electric swltches, filed November 23, 1922; Ser. No'.v 602,702, electric switches, tiled November 23, 1922; and Ser. No. 491,128, electric switches, led Aug. 10, 1921 respectively, which are also assigned to the same assignee as the present application. i

Other objects and advantages will appear as the description proceeds.

Referring to the accompanying drawings, Fig. 1 shows in elevation and partly in section a switch provided with a movable perforated baffle constructed in accordance with my invention; Fig. 2 is a similar view of a modified form of switch in which the perforated baffle is stationary; Fig. 3is a detail showing a slightly different means for holding gravel in the baffle; Figs. 4 to G inclusive are sectional views showing the application of my invention to other forms of switches.

Referring to Fig. 1, 10 represents a tank or casing which is provided with a cover 11. This tank and casing/should be constructed to withstand considerable internal pressure. Supported from insulators 12 which are carried by the cover are stationary contacts 13 of the switch. The movable contacts 14 are carried upon a rod 15 which extends upwardly through an opening 16 formed in the cover 11. Cover 11 may be spaced from the top of the tank 10 at points around its periphery as indicated at 17 Vto form vents. Located within the tank 10' is a bale which comprises a top portion 18 and a depending portion 19 which in the switch shown is preferably of cylindrical form. The top portion 18 is formed of a casing 20 composed of horn fibre or similar material and has perforated top and bottom plates 22 vbetween which is located the granular material 23. This material is preferably one which has a high dielectric strength, such for example as quartz gravel. The gravel may vary considerably in size but for many switches I find that pebbles from l@ to 1%: inch in diameter are very satisfactory. However, it should be noted that while I refer to this material as gravel, I desire it to be understood that I do not wish to limit myself to any particular size of pebbles or particles of which this material is composed.

Suitable openings 24 and 25 are provided for the passage of two insulators 12 and the rod 15 through the body portion of the baffle thereby allowing the baliie to move vertically within the container, and suitable blocks 9 are provided against which the bafiie may bear in its upper portion. Fig. 1 shows the baile raised somewhat from its lowermost position in which latter position the depending portion 19 will rest upon the bottom of the tank 10. In practice the tank l0 is filled with oil to the level indicated which in the lower position of the loailiie-V The depending portion 19 prevents the gas from escaping around the battle and the pressure produced by the generation and expansion of these gases raises the baflie which thus acts as a safety device to prevent the pressure from becoming excessive. The limitation of pressure is desired not only because of the fact that too great a pressure will cause direct injury to the apparatus, but also because the amount of gas generated by the arc is dependent upon the pressure upon the arc stream. The gas upon being liberated rises in the oil and passes up through the body portion of the baille where it is cooled by contact with the gravel and a portion of the same condensed. The remainder has its temperature so lowered that it will not ignite when it comes in contact with the air.

In the form shown in Fig. 2 the battle is stationary and comprises a casing 28 suitably secured to the cover 11. The casing may be perforated along its bottom and sides and spaced at its sides from the wall of the tank 10.

, In Fig. 3 I vhave'shown a modified form o-f baHle in which a wire vnetting 30 may be placed between the gravel and the containing `casing 31. This would havethe advantage of strengthening the baiile. If desired, the baiile may be formed of a quantity of such woven or unwoven wire folded, bent or otherwise compressed into the space within the casing 31.

In Fig. 4 is illustrated the application of my 'gravel bale to a switch of the so-called explosive or oil blast chamber type. That portion of the apparatus illustrated in Fig. 4 is adapted to be immersed in an oil tank, not shown, and the electrode 33 is adapted to 'be secured to an insulator which passes through the cover of the tank. Rigidly secured to the electrode 33 is a pot 34 formed of a body portion of steel and the bottom likewise of steel. The body portion is formed with valve openings within which are adapted to be seated valve heads 35. The valve heads are carried upon stems 36 which operate in openings 37 formed in a circular plate 38. Springs y39 interposed between the heads 35 and plate 38 serve to force the valves into their seats. Plate 38 is provided with screw threads around its periphery which engage threads 40 formed in a metallic ring 41 set in the insulating shell 42. The plate 38 forms a tight joint between the pot 34 and the shell 42 except for a small bleed hole 43. Between the pot 34 Y and shell 42 is the gra'vel 44 which is held between perforated rings 45 and 46 of insulated material. These rings are held in place by pins 47 and 48 which extend inwardly fromthe shell 42. 49 designates an insulator seated in a center opening 50 in the bottom of the pot 34. Through this insulator passes the tubular movable electrode 52. The pot 34 is lined on the inside and covered on `the outside with insulated material as indicated at 53.

Normally theoil in and around the shell 42 is maintained above the metal on the lower end of insulatorsupportinf the explosion chamber, the pot 34 being Iiept full. When the electrodes 33 and 52 are separated to break the circuit, the arc formed creates a pressure which causes oil contained in the pot 34 to be forced downwardly through the center of the electrode 52 and between the electrode 52 and the insulator 49. In operation the upper end of th'e electrode 52 passes down through the insulator 'and the blast of oil across the end of the metal tube extinguishes the are. The pressure within the pot 34 is limited by the valves which open and permit the gas and-vapor to escape into the 'space beneath the plate 38. This space may contain a small amount of air, suiiicient to form a cushion for the escaping gas, and so prevent damages to the apparatus by the force of the expulsion. The pressure created in this space causes the oil and gas to be forced downwardly through the gravel 44, after which they rise through the oil in the outer tank and pass through passages similar to those shown in Figs. 1 and 2. `1 It will thus be seen that the device illustrated in Fig. 4 has the advantage of employing an oil blast to extinguish thev arc and causes the gas to flow under pressure through a circuitous path to its outlet along a considerable portion of which it passes over the cooling surface of the gravel.

In Fig. 5 I have illustrated still another modification in which I combine a double oil blast feature with my impro-ved cooling means. vIn this form I provide a metallic casing 60 closed at the topby means of a cover 61 having a small outlet passage 62. This casing forms one terminal of the switch and is provided with a stationary contact 63 adapted to cooperate with a movable contact 64. Suspended fro-m the cover 61 by means of the insulator 65 and metal tube 66 is a metallic pot 67. Electrode 64 passes centrally through this pot and between the electrode and the bottom of the pot is located an insulator 68. A small opening 69 serves as a bleed hole for the pot. Extending the length of the casing are wooden rods 70 which are formed with shoulders 7l upon which is supported a perforated ring i72 of insulated material. Between this ring and l the perforated ring 73 is the gravel 74.

Baliles 75 and 76 'are located above the gravel baffle and these are provi ed with nonaligued cut-away portions f r the passage of gas to the outlet opening 2. Surroundin the movable electrode adjacent its lower end and spaced therefrom is a baffle or partition 77. Baies 75, 76 and 77 may be supported by tubes of insulation 80 which surround the rods 70.

The operation of this form of ,invention is as follows: Upon separation of the contacts an arc is formed within the casing 60 beneath the baille 77. This creates a pressure within the space below the baiile and as the lower end of the electrode 64 passes up through the opening in the baille a blast of oil is directed into the path of the arc. Likewise, as the end of the electrode 64 moves through the insulator 68 and draws the are upwardlywithin the chamber formed by the pot 67 a pressure will be created in this chamber as a result of which oil will be forced from the chamber downwardly through the opening in the insulator 68. It

will thus be seen that the two oil blasts mbving in opposite directions are projected into the path of the arc and serve effectively to extinguish the same. Gases and vapor which are formed beneath the insulator, as

well as any which may pass downwardly through theopening in the insulator, rise through thel casing and pass through the gravel 74. Baflles'7 5 and 76 in addition to` urnishing a further cooling surface Jfor the gases serve to lengthen the pathvto the outlet openings 62. The space beneath the baffle 77 as well as the space within the pot 67 I term a pressure chamber while the space aroundthe pot 67 but within the casing 60 I term a discharge chamber.

Fig. 6 shows another form of device in which I take advantage of the pressure of the gas formed by the discharge priorto its cooling to create an oil blast to extinguish the arc. In this form the movable electrode 83 passes up through a funnel-shaped opening 87 formed in an insulating partition 84. Surrounding the electrode and depending from the partition 84 is a cylindrical shield 85 of insulating material and connecting the space outside of said shield with the funnelshaped opening 87 are passages 88 and 89. Baflies 90' and 91 are located above the parti-v tion 84 while between the perforated ring 92 and the top 93 of the external casing is located the gravel 94. The tube 95 which passes through the 'cover 93 and serves to conduct the gas away from the casing 96 also contains gravel. If desired this tube may be extended so that the gas will be discharged at some place remote from the switch. In order to prevent gas in the casing from escaping:

around the movable electrode, I arrange in the passage 97 through which the electrode 83operates,v a stuiing box 98. This comprises a' leather disc 99'Which surrounds the elec-V trode 83 and a metal cap 100 against which 'the disc is forced by the pressure of the gas to break the circuit, the gases formed cause oil to be projected through the passages 88 and 89 into the path of the arc stream and acts to cool it. The shield 85 serves to keep these jets of oil substantially free from gas.

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

1. An oil switch provided with an outlet for the gases formed by the opening of the circuit and a porous mass forming a plurality of extended narrow passages for the escape of saidV gases located in said outlet.

2. A switch having contacts adapted to be separated beneath the surface of an insulating fluid and a plurality of extended narrow courses of escape through insulated material for the fluid ejected from the space .surrounding said contacts upon the opening of said switch.

3. A11 oil switch provided with an outlet for the gases formed by the opening of the circuit and a cooling means in the path of said gases, said cooling meanscomprising an'aggregation of individual particles with rounded edges.

4C. An oil switch provided with an outlet for the gases formed by the opening of the circuit and a coolingl means in the path of said gases, said cooling means comprising an aggregation of individual particles with rounded edges', said particles having a. diameter of not less than 1A; inch.

5. An oil switch having a plurality of eX- tended narrow courses of escape through insulated material for the gases formed by the opening of said switch, said courses being located above the surface of the oil.

6. An oil switch provided with a gravel baiie arranged in the path of the material ejected on -the opening of the switch.

7. An oil switch provided with a yielding gravel bafiie arranged in the path of the p gases, produced by the opening of the switch. i

8. In an oil switch, a tank adapted to contain oil, cooperating contacts adapted to be separated beneath the surface of said oil,

a movable perforated baffle in the path of the gases produced by the opening of the circuit, the parts being so constructed and arranged as to providean air space behind said' baffle to permit said baiiie to yield under the pressure of said gases.

9. A combination of a tank having an outlet at the top thereof, switch contacts within said tank, a vertically movable bafiie Within said tank, said baffle comprising a body portion formed of a perforated casing and granular material within said casing and an imperforate depending portion which surrounds said contacts and normally rests upon the bottom of said tank, the parts being so constructed and arranged as to provide an air space between the top of said baflie and said outlet.

10. In a'iuid switch, the combination of a fluid break containing vessel and cover, insulating fluid within said vessel, separable electrical contacts beneath the surface of said insulating iuid and a perforated barrier supporting granular cooling means in the space above said insulating fluid.

11. In a fluid switch, the combination of a fiuid break containing vessel and cover, in-

sulating fluid within said vessel, separable electrical contacts beneaththe surface of said insulating fiuid and a perforated insulating barrier supporting a non-conducting granular cooling means in the air space above said insulating Huid.

12. In a fiuid switch, the combination of a fluid break containing vessel and cover, insulating fluid within said vessel, separable electrical contacts beneath the surface of said fluid, and a movable mass of cooling material in the space above the surface of said insulating fluid.

In witness whereof, I have hereunto set l my hand this 7th day of February, 1921.

JOHN D. HILLIARD.

l Certicate of Correction. A .It is hereby certified that-in Letters Patent No.`1,537,353, granted May 12, 1925,

Y upon the application of John D. Hilliard, of Schenectady,

improvement in Electric Switches, errors appear 1n the New York, for an rinted specification requiring correction as follows: Page 4, lines 73, 80, and 88, c alms 10, 11, and. 12, strike out the word break and insert `the same after the word fluid 1n lmes 72, 7 9,' and 87, of the same claims; and that the" said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.-

4Signed and sealed this 30th day of une, A. D. 1925.

[sEALL] KARL FENN ING, A ating Commissioner of Patents'.

Images