US1706746A - Electric switch - Google Patents

Description

March 26, 1929, c. w. me: I 0 ,7

ELECTRIC SWITCH Filed March 17, 1924 2 Sheets-Sheet 1 Inventor:

Chester \M'Rice,

His Attorney March 26, 1929. c. w. RICE 1,706,746

gmac'rmc SWITCH Filed Marph 17, 1924 2 Sheets-Sheet 2 Fig. 3.

Inventor:

Chesterw R ice His Att orn ey Patented Mar, 26, 1929..

' UNITED STATES CHESTER W. RICE, OF SCHENECTADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC? COMPANY, A CORPORATION OF NEW YORK.

ELECTRIG SWITCH.

Application filed March 17, 1924. SeriaI-\..No. 699,660.-

My invention relates to electric switches, and particularly to electric switches which are adapted to control high potential circuits.

For the control of such circuits it is customary to employ switches of the fluid break type in which the initial breaking of the circuit and the final closing thereof is effected between contacts immersed in an insulating oil. With such a'switch the are drawn upon the separation of the contacts causes a rapid dissociation of the oil giving rise to the sudden formation of a relatively large volume of highly heated gas which in the case of a heavy overload or short-circuit on the line may result in the production of an enormous pressure. Although strong steel containers have been employed to withstand the pressure developed under such conditions much difliculty has been experienced in preventing the expulsion of hot oil and gas which has often resulted in causing short circuits in the vicinity of the oil switch and the starting of fires as well as the loss of considerable quantity of oil from the switch.

An object of my invention is to provide a switch of an improved type which can be suc-' cessfully employed for the control of high potential circuits without the diiiiculties and dangers heretofore encountered with switches f of the oil break type.

According to my invention the switch contacts are mounted to be separated in a vessel filled with hydrogen under pressure. Among the more important advantages of the use of hydrogen as a medium in which the contacts of a high potential switch are separated, there may be mentioned the following: first, the large amount of heat consumed in dissociating the molecular hydrogen into atomic hydrogen in the arc stream; second, the high heat conductivity of molecular and atomic hydrogen whereby theintense heat of the arc is rapidly conducted away, thus assisting in the cooling and final breaking of the arc; third, the absence of any permanent gas formation due to the products of dissociation of the medium in which the are is drawn;

' fourth, the possibility of increasing the rate of recombination of the atomic hydrogen by placing catalyzing materials or surfaces in the vicinity of the arc stream; and fifth, the high dielectric strength as compared with oil which may be obtained by using a gas such as and its scope will be hydrogen, particularly when it' is confined under pressure. This last is of importance in preventing the reforming of the arc.

My invention will be better understood from the following description taken in connection with the accompanying drawing,

pointed out in the appended claims.

In the drawing, Fig. 1 is a diagrammatic illustration-of my invention; Fig. 2 is acrosssectional view of a form of switch embodying my invention; and Fig. 3 is a fragmentary cross-section drawn to a larger scale taken on line 33 of Fig. 2.

Referring first to Fig. 1, a gas-tight chamher is represented at 1 to which two pipes 2 and 3 connect, the pipes being controlled respectively by valves 4 and 5.- Two similar stationary contact members 7 and 8 are shown supported by insulators 9 on the bottom of the chamber, each contact having attached thereto a lead 10 passing through the side of the chamber and being insulated therefrom by means of an insulating bushing 11. The movable contact member 12 bridges the stationary contact members 7 and 8 when the switch is closed and is attached at its central portion to a rod 13 which is carried by the solenoid core 14:. The solenoid 15 for raising the movable contact member surrounds the core 14 and is' connected to leads 16, passing out through the chamber by means of insulating bushings 17. By means of the two pipe connections 2 and 3 the air within the chamber may be removed and hydrogen at the desired pressure substituted therefor.

In Fig. 2 the gastight chamber is shown comprising the cylindrical body portion and two end- heads 23 and 24 secured thereto. The chamber has alining 25 of insulating material and in each end-head is secured an insulating bushing 26 through which extends the conducting rod 27, a suitable stationary switch contact 28 being mounted on the inner'end of each rod 27 For admitting hy drogen to the chamber and for scavenging the same of air two pipes 30 and 31 each having a control valve are shown entering the body portion; a third pipe connects the pressure gauge 32 to the chamber. This pressure gauge obviously may be arranged to control a valve by which hydrogen may be admitted to the chamber from a storage reser- Ill a way as to voir, thereby retaining the desired pressure of gas in the chamber in the event of a slight leak therein.

The movable elements of the switchcomprise two solenoid operated contact members 33 which engage the-two stationary contacts 28 and against which bear the brushes 34:.

shown supported "and guided by the member 4-2 which is secured to the body portion 22 of the chamber by means of an insulating post 43. To prevent a disposit of metal on the bushings 26 by the are between the metallic contacts I have provided each bushing with a shield 44.

For the purpose of increasing the rate of recombination of the atomic hydrogen into molecular hydrogen 1 may provide catalyzing means within the switch chamber. Such means will be most efiective when arranged in the vicinity of the are stream. The rate at which the arc stream is cooled will thereby be increased. In Fig. 2 the catalyzing means is indicated as consisting" of ring-shaped members 45, 4.6 which may be composed of tugsten, or may be composed of quartz having ground surfaces. Other known catalyzing agents may be used such as ordinary glass with a ground surface or catalyzers comprising thoria or aluminum. W'here catalyzing members of quartz are used, thesemembers may be arranged side by side parallel to the arc stream with their lower edges slightly above the line of the break. Thus arranged the arc will be divided up into a series of small arcs in parallel and the quenching of each arc will be facilitated by the catalyzing effect. The quartz is capable of withstand ing the high temperatures without injury.

In the arrangement shown in Fi 2 each member 46 is shown as having a ange 47 which partially shields the lining of the chamber from themetal vapor, the members 4:5 and 46 are preferably supported in such rovide a free circulation of hydrogcnwithm the chamber. If, after con tinued use, the catalyzing members become ineffective, as for example by reason of deposits thereon due to the vapor of the are stream they may be replaced. Where catalytic efiects are found desirable, hydrogen which is dry and free from oxygen, is preflid erably usedsince water vapor and oxygen have a poisoning edect. on the catalyzer. Where the switch chamber is lined with a material which has marked catalyzing properties, it may be found under certain circumstances that the lining itself is a suflicient catalyzer to improve the action of the switch. In such case the construction must be such that the lining and casing are not damaged by the heat produced asa result of the recombination of the hydrogen atoms. The catalyzing action may be controlled by the admission ofa slight amount of water vapor or pxygen to the chamber deliberately to poison the catalyzing surfaces. If, therefore, in any case the catalyzing action is such as to tend to damage the lining it may be eliminated by the introduction of a poisoning agent. It is deemed preferable to employ catalyzing members supported adjacent the arc stream and provide a lining which does not possess catalyzing properties to any c.on siderable degree. The catalyzing action may be preserved by the insertion of caesium and calcium in the chamber which will take 11 oxygen and water vapor.

By means of the pipe connections 30 and 31 the chamber maybe scavenged of air and filled with hydrogen. Since the dielectric strength of hydrogen increases with the pressure, it is preferable, where practicable, to

atmospheres. My invention is not, however,

limited to such pressures since marked advantages are secured by the use of hydrogen at pressures approximating atmospheric pressure. Comparative tests made with a switch operating under similar conditions in an atmosphere of air and in an atmosphere of hydrogen have shown that in hydrogen the length of are drawn before final rupture is only about one-tenth that drawn in air.

It will be obvious from an inspection of the drawing that the energization of solenoid 86 will shift the plunger 39 and thereby contractthe lazy tong mechanism to move the movable contacts to open circuit position. The resulting arc, beingdrawn through hydrogen under pressure and inthe immediate vicinity of the catalyzing agents, is quickly extinguished, and the medium in which the arc Was drawn upon cooling, will return to substantially its original condition as regards pressure and composition. Ener gization of. the other solenoid 35 likewise effects the closing of the switch.

While I have described certain embodiments of invention, I do not wish to be limited to the arrangements shown and described as it will be apparent that many modifications therein may be made without departing from the scope of my invention as set forth in the appended claims.

What claim as new and desire to secure by Letters Patent of the United States, is 1. Aswitch comprising a closed chamber containing hydrogen, relatively movable metal contacts in said chamber, means for insulating one of said contacts from said chamber, and shielding means for preventing metallic deposits on said insulating means due to an arc said contacts.

2. A switch comprising a closed chamber containing hydrogen, relatively movable cooperating contacts mounted therein, and cat.- alyzing means in said chan'iber whereby atomic hydrogen is caused to recombine into molecular hydrogen.

produced upon separation ot 3. A switch comprising a closed chamber containing'a polyatomic gas dissociable under the influence of an electric are, relatively movable,- cooperating contacts mounted in said chamber whereby the are formed upon the separation of said contacts may dissociate a. portion of said gas, and catalyzing means in said chamber for causing a recombination of said dissociated portion. V

In witness whereof, I have hereunto set my hand this 14th day of March, 1991.

. CHESTER WV. RICE.

Images