US1872310A - Means for interrupting electric circuits - Google Patents

Description

Aug. 16, 1932. A. LOTZ 72 MEANS FOR INTERRUPTING ELECTRIC CIRCUITS Filed March 27, 1931 min/5555 INVENTOR 4 yw i/brfAofZ Y 2 A'II'TORNEY Patented Aug. 16, 1932 UNITED STATES PATENT; OFFICE ALBERT Lo'rz, or nnaLm-smmanssranr,

GERMANY, .ASSIGNOR o .WESTIN'GHOUSE ELECTRIC & MANUFACTURING COMPANY, A'coarom'rIoN or PENNSYLVANIA mans on rmimnurrmo ELECTRIC crncurrs Application 'flled um a1, 1931, Serial No. 525,679, and a Germany March 27, 1030.

My invention relates to an electric-circuit interrupter and, particularly, toelectric-circuit interrupters utilizing porous objects filled with conducting fluid which will be evaporated by the heat of the current flowing therethrough. e

It is an object of m invention to utilize the heat of the current owing through a porous resistanceimpregnated by a conducting 1o liquid to eva orate the liquid and thereby interrupt the ow of current. V I c It is a further object of the invention to provide a circuit interrupter which will be cheap to manufacture and which will have no moving parts.

It is a still further object of the invention to provide a circuit interrupter havin no mtiying parts but which may be varie at w1 vso It is an ancillary object of the invention to provide a device which may be utilized as a circuit breaker per se, as'a time delay switch or as an overload relay.

It is another object of the. invention to so construct a resistance liquid switch that gases formed by electrolysis at the electrodes will be unable to break down electrically and, therefore, will not cause arcing.

Other objects and advantages of the invention will become apparent from the following description and drawing, wherein The single figure is a cross-sectional view of a preferred embodiment of my invention, showmg a porous insulating mass, the capili lary spaces of which are filled with a liquid.

For interrupting a hi h-tension circuit without the formation 0 an arc, switches have been proposed in which a liquid resistance is gradually introduced into the circuit to be broken. Precautions must be taken to prevent the formation of gas or vapor between or at the electrodes because the gas pockets would break down and cause the formation of an arc in the liquid between the electrodes.

According to this invention, the formation of an arc is to be prevented by introducing into the circuit a body of porous insulating material, the pores of which are filled with a resistance liquid. A gradual increase in resistance will, according to the invention, result from the fact that the liquid in the pores will be evaporated by the heating effect of, the current. Vapor formation between the electrodes will not lead to the formation of an arc, in this case, because an arc cannot exist in the capillary spaces. 1 The greatest difficulties in these resistance liquid switches are met with at the electrodes, since the current density reaches its highest value at these points. Gases are formed'by electrolysis and these easily break down electrically. When water or aqueous solutions are used, hydrogen is formed at the cathode. According to the invention, these difiicultiesare avoided by so designing the porous bodyfthat the cross section is smaller in the part between the electrodes than it is at the electrodes. vaporization will occur at the point of maximum current density, which, in this case, is some distance away from the electrodes. While a gas which is formed at the electrode will break down immediately in the electron stream emitted by the glowing cathode,ithe gas volume, in the present instance, is surrounded by liquid and, therefore, will not become ionized. I i

The porous insulating material which i used may be burned clay, loose sand or any otherisuitablematerial. Pure water may be used for theliquid. To increase the conductivity of theliquid, it is most desirable to add substances which will vaporize with the liquid and leave no conducting residue. 1 Substances of this kind are ammonia, nitric acid, formic'acid, etc. a

Referringspecifically to the drawing, one example of the device, which is the sub ect of this application, is shown.

Numeral 10 designates the porous, insulating mass, the capillary spaces of which are are provided with disconnect switches 13 and 14. A switch 15 is provided to short circuit the porous mass 10.

Current interruption proceeds in the following manner.

First, the main switch 15 is opened. This throws the porous mass 10, filled with a liquid conductor 9, into tne circuit. The resistance of the liquid must not be too high, in comparison with the resistance of the other portions of the circuit.

T he current then flows through the liquid contained in the porous mass 10, and the liquid will start to evaporate at the constricted section 16, which is the point of greatest current density. The vaporization is gradual and the resistance of the conductor increases constantly. The resistance at the electrodes 17 and 18 remains relatively small. \Vhen the liquid, in a certain length of the cylindrical portion of the body at the point- 16, has been entirely vaporized, current interruption is complete. Arc formation cannot occur for the reasons already mentioned.

After the circuit has been broken, the switches 13 and 14 carry no current but must be opened because liquid will be drawn up into the section where the currentwas interrupted and this would again close the circuit.

The porous body 10 may be filled with the conducting switching liquid 9 by immersing it in a vessel containing the liquid. It may then be removed and placed on the electrodes for use. Other means may be used to keep the vaporization away from the electrodes; for instance, certain portions at a distance from the electrodes may be preheated.

From the foregoing description, it will readily be seen that I have constructed a liquid-resistance switch which may be cheaply and easily manufactured and which will have no moving parts. The interrupter may be varied at will by keeping the ends immersed in a predetermined amount of liquid.

The invention may be used as a circuit breaker, as described, or as a time switch by determinin first the time taken under a specified set of conditions for causing current interrupt-ion. t may also be used as a time overload relay by so balancing the constituent parts that evaporation will not occur until a predetermined maximum current is attained.

It is also obvious that the disadvantages of liquid-resistance switches are overcome by placing the porous mass in the circuit VhQI'Q. by gases generated by the electrolysis around the electrodes, which will ordinarily break down electrically at a low current value, will not be able to break down since it will be disseminated throughout the porous mass.

Although I have shown and described a specific embodiment of my invention, it will be understood that modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A device for interrupting electric currents in a. circuit comprising a pair of electrodes, aresistance connected across the electrodes comprising a resistance liquid and a porous body of insulating material, said body being placed between said electrodes and being at least partly filledwith said liquid'to conduct current, the cross section of said porous body being less at the points between the electrodes than at the electrodes.

2. A device for interrupting electric currents in a circuit comprising a pair of electrodes, a resistance connected across the electrodes comprising a resistance liquid and a porous body of insulating material, said body being placed between said electrodes and at least partly filled with said liquid toconduct current, said liquid being such that it evaporates withoutleaving a substantial residue.

3. A device for interrupting electric currents in a circuitcomprising a plurality of electrodes, a resistance connected across the electrodes comprising vessels filled with resistance liquid and a porous body of insulating material, said porous body being placed between said electrodes and at least partly impregnated by said liquid for conducting current, the cross section of said body being less at the points between the electrode than at the electrodes, the ends of said porous body being disposed in vessels filled with liquid.

In testimony whereof, I have hereunto subscribed my name this 7th day of March. 1931.

' ALBERT LOTZ.

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