US1761091A - And arc-extinguishing means - Google Patents

Description

. June 3, 1930. E. o. SCHWEITZER 1,761,091

CURRENT INTERRUPTING AND ARC EXTINGUISHING MEANS Filed Feb. 26, 1923 3 Sheets-Sheet 1 June 3, 1930. E. o. SCHWEITZER 1,751,091

CURRENT INTERRUPTING AND ARC EXTINGUISHING MEANS Filed Feb. 26, 1925 3 Sheets-Sheet 2 June 3, 1930. E. o. SCHWEITZER 1,761,091

CURRENT INTERRUPTING AND ARC EXTINGUISHING MEANS Filed Feb. 26, 1925 :5 Sheets-Sheet 3 Patented June 3, 1930 PATENT OFFICE EDMUND O. SCHWEITZER, OF CHICAGO, ILLINOIS GURRENT-INTERRUPTING AND ARG-EXTING'UISHING MEANS Application filed February 26, 1923. Serial No. 621,357.

My invention relates to current interrupt-- ing and are extinguishing means.

In interrupting heavy currents of electricity either by a purely switching operation or automatically by means of'protective apparatus the physical separation of the electrical contacts, terminals or conducting parts, where the current is to be interrupted, is a relatively simple matter in itself. However, the physical separation of the conducting parts does not necessarily entail an interruption of the current flow as the current flow continues in the shape of an arc of greater or less severity depending upon such factors as voltage, speed of separation of the conductors, resistance and reactance of the circuit, frequency and the like. lvhether the condition of interrupt ing the current flow be caused by a purely switching operation or automatically by an over-load circuit breaking device, breaking the continuity of the normal conducting path results in the formation of an arc of greater or less severity. Increased voltages increase the di' iculties of interrupting the current flow.

In my copending application, Serial No. 593,248, filed Qctober 9, 1922, I provide for maintaining the electrical contacts or conducting parts in a bath of oil for insulating purposes and for delivering to the point of interruption upon separation of the contacts, a suitable arc extinguishing liquid which will quickly and effectively extinguish the arc and whichwili, when vaporized, give off a noninnammabie arc-extinguishing vapor. In, this manner, the advantages of oil, among which are the fact that it will not attack and corrode the physical contact makin and breaking means employed and the enclosing casing and its ability to maintain its value as an insulating medium, especially when exposed to air and moisture, and the advantages of the arc extinguishing liquid among which are the fact that it gives ofi" a non-inflammable arc extinguishing vapor and its arc extinguishing ability, especially in interrupting a heavy current or on a heavy overload are taken advantage of, and the disadvantages of each are overcome.

A more specific provision of the aforesaid invention is for injecting or delivering a jet of the arc extinguishing liquid upon the arc and contacts at the point of interruption, as the contacts separate. This necessitates means for injecting or delivering the are extinguishing liquid and where fluid pressure means is desirable, I find that a further practical problem is presented. Air under pres sure as a source of fluid pressure for injecting or delivering the arc extinguishing liquid has a number of marked disadvantages. Its combustion supporting property presents a potential danger. If the interrupting device is operated when the quantity of arc extinguishing liquid is low so that the arc extinguishing liquid is all delivered or injected and the air follows through to the point of interruption or in any other manner reaches that point during interruption, an explosion may result or at least the arc will be increased instead of extinguished with an accompanying continuation of the current flow, endangering the apparatus in the line and lives and apparatus nearby. Furthermore, air causes corrosion and permits moisture accumulation which causes deterioration.

To secure a suit-able speed of injection of the arc extinguishing liquid so that minimum damage may be done by the are, I provide a gas under pressure which by its expansion can force the liquid from the reservoir which contains it, through the nozzles and into the path of the arc.- Compressed air will not serve. It would make matters worse by forming, in conjunction with the oil vapor, an explosive combustible mixture. Air in the oil tank is about the worst thing that could be introduced. I employ a cylinder of liquefied carbon dioxide gas, such as may be secured on the open market, and permit the gas at a suitable pressure as may be controlled by a reducing valve, to press upon the surface of the arc-extinguishing liquid in the tank or reservoir containing it. I find that the CO gas is peculiarly suitable because of its inert characteristics, both with respect to'the liquid which it engages, and also with respect to the are itself and the metal vapors and the metallic contact and switch. parts with which it comes in contact. It is also cheap and plentiful in addition to its other desirable characteristics.

Now if the arc-extinguishing liquid should be all expended before the tank or reservoir is refilled, the carbon dioxide gas merely follows and serves as an arc-extinguishing fluid of less effectiveness than the liquid, but highly advantageous in blanketing the oil or the vapors against explosion.

Another object is the provision of an improved expansion chamber for relieving the pressure when the interruption occurs in an enclosure or well and heavy arcing and excessive vapo *ization takes place. In its broader aspect, this chamber operates to increase the volume of the well, and in its more specific aspect, it is operated by the pressure created to increase the volume of the well and simultaneously render vent means active and increase the action of said vent means as the volume of the well is increased.

Another object is to provide for automatically interrupting the circuit upon a slight abnormal condition or a slight disturbance, relying upon the oil or other liquid bath normally surrounding the circuit terminals to extinguish the arc and for automatically interrupting the circuit and delivering the are extinguishing liquid held in reserve to the point of interruption upon the occurrence of a heavier surge of current or a disturbance of greater severity.

In order to apprise those skilled in the art with the operation and the manner of utilizing and practicing the invention and where they enter into the invention with the construction and substances for carrying out the several aspects of the invention, I shall now describe a particular embodiment in connection with the accompanying drawings which form a part of the present specification.

In the drawings Fig. 1 is a more or less diagrammatic vertical sectional view through a well known type of oil switch showing the application of the features of my invention thereto;

Fig. 2 is an enlarged front elevational view of the oil switch showing the expansion chamher in section;

Fig. 3 is a side elevational view of the switch showing the expansion chamber in elevation; and

Fig. 1 is a detail horizontal section through the expansion chamber on line 44 of Pi g. 2.

In the embodiment of the invention selected for illustration, 5 designates a closed vessel or container provided with a cover 6 through which projects the main line conductors or high tension connections 7 and 8 terminating in stationary switch contact members or terminals 9 and 10. These contact members 9 and 10 may be of any desired form and need not be described in detail here. Conductors or connections 7 and 8 which are connected to said contact members 9 and 10 are led through cover 6 by means of insulators 12 12 which may be of any suitable or preferred type. Insulators 1212 support contact members 9 and 10 and said insulators are preferably sealed into cover 6 so that a tight joint is maintained.

A movable switch member 15 adapted for reciprocation into and out of contact with stationary contact members 9 and 10 is mounted on a suitably insulated rod 16 which extends up through and is guided in cover 6.

A compression spring 18 between the upper end of rod 16 and a relatively fixed alnitment tends to force rod 16 downwardly and switch member 15 carried thereby out of engagement with switch contact members 9 and l0. A solenoid 22 controls a pawl or catch 24: which is adapted to engage under a flange or shoulder 25 at the upper end of rod 16 to hold switch member 15 in engagement with contact members 9 and 10 against the action of spring 18. A spring 26 normally tends to force pawl 2a: into engagement under the flange or shoulder 25. Energization of solenoid is controlled by a relay 28 actuated by a suitable current transformer 30 in the main line 7-8, magnet 22 being energized through lines 32- 32 when relay 28 is closed by an overload or other disturbance or abnormal condition in main line 78.

- A nozzle 35 having flat wide mouth is mounted in the wall of container 5 adjacent each of the switch terminal members 9 and 10 substantially as'more specifically shown in the co-pending application which I have already referred to. These nozzles 35 are preterably of insulating material so as not to impair the insulation of the switch parts within the container. The container may also be lined with insulation, but this is not shown here.

In the particular embodiment shown closed container 5 holds a body of liquid 12. Any other suitable or preferred liquid may be provided at this point where liquid used at all, oil, because of its advantages as a permanent bath normally surrounding the circuit terminals is preferable. Conduit means is provided for delivering the arc extinguishing liquid 46 held in reserve from a tank or other suitable source 48. A valve 50 in conduit 1-5 controls the delivery of arc e1;- tinguishing liquid 46 through the nozzles 35. Valve 50 is controlled by a lever 52 and is normally held in closed position by a s n'ing 55. It is opened to deliver are extinguishing liquid from tank 48 through nozzles by the action of a solenoid 5S diagrainmatically shown as a winding having a core 62. Iluergization of winding 60 is controlled by a relay actuated by a transformer 30 in the main line 78, winding 60 being energizer'l through lines 82-32 when relay 65 is closed by an overload or other disturbance or ab normal condition in line 7 8 to open valve and deliver arc extinguishing liquid through nozzles 35 to the point of interruption.

The liquid 46 is preferably carbon-tetrachloride or a liquid such as that disclosed in U. S. Patent #1319307, granted @ctober 28, 1919, to Nicholas J. Conrad and myself. In this manner, the valuable arc and fire extinguishing properties of the arc extinguishing liquid held in reserve are secured without the disadvantages of normally surrounding the circuit terminals therewith. Of course, the invention is not limited to the use of a particular fluid at these points.

The fluid pressure means which I provide for delivering the arc extinguishing liquid 46 is delivered from a tank 74 to the top of tank 48 through a conduit or pipe connection 73 therebetween. A pressure reducing valve 75 is provided in the conduit or pipe connection 73 between tanks 74: and 48, so that the fluid pressure means may be maintained in tank 74, for example, at a pressure higher than that required for delivering the arc tinguishing liquid at) through nozzle 85 to the point of current interruption when the switch is opened and supplied at the pressure desired for properly delivering the arc extinguishing liquid. Of course, if the fluid pressure means is maintained at a pressure suitable for the desired delivery of the arc extinguishing liquid, the reducing valve may be dispensed with. A high pressure however permits a greater reserve in a smaller area, and that is desirable. In practice have employed a cylinder of liquefied bon dioxide such as is used at soda fountains. When a cylinder is substantially empty l substitute a fresh cylinder. Where a reducing valve is employed, it may of course be adjusted to give any desired delivery pressure upon the arc extinguishing liquid. Tank as is provided with a pressure "FO and a level indicator 72. Supply means may of course be provided for automatically maintaining a constant level of arc extin guishing liquid in tank l8 at substantially the point shown.

As already pointed out, the fluid pressure means is primarily a commercially luid that may be maintained at the desired pressure and is at the same time incapable of supporting combustion and one that will not affect or spoil any of the desired qualities the arc extinguishing liquid. The particular fluid which I have discovered to be valuable in this connection and which I at this time deem preferable, is carbon dioxide (G0 if it reaches the point of circuit interruption, there is no danger of explosion, or of its increasing the are but to the contrary, proper interruption of the current flow and extinguishment of the arc is aided. I do not intend to be limited to this particular fluid,

' conduit 81 with the interior of well or container 5 preferably at a point adjacent the top thereof. Conduit 81 comprises a relatively short vertical tube, supporting sleeve or tube at its upper end and communicat ing with said sleeve or chamber 80 through the bottom thereof, and a relatively short horizontal tube connected by a suitable elbow. The relatively short horizontal tube is threaded into fitting 82 which is in turn riveted, bolted or otherwise secured to the wall of container 5 about the point of entrance of conduit 81 thereinto.

A hollow piston 85 closed at its upper end and open at its lower end is slidably mounted in tube 80. Piston 85, the external diameter of which is less than the internal diameter of tube 80 to provide an annular space between the tube and piston is positioned concentrically within tube 80 by four diametrically opposite spacing strips 86 arranged vertically between the tube and piston. An inverted ti -shaped strap 88, the free ends of which are secured to tube 80 as by rivets 89, limits the outward or upward movement of piston 85.

From the foregoing, it will now be apparent that when interruption occurs and pressure is createddangerously high pressures result where heavy arcing and vaporization takes place piston 85 is forced outwardly or upwardly through tube or conduit 80 by such; pressure. This results in a quick increase of the volume of the well and a quick relief of the pressure. At the same time vent passages out between strips 86 and the exterior of piston 85 and interior of tube 80 are opened, the size of these openings and thereby the action of the vent means increasing as the volume of the well is increased by the upward or outward movement of piston 85. Upon resetting the switch, piston 85 is forced down to the lower or inner end of its movement, closing the vent openings and retur ing the well or container to its normal. volume. The vent means may of course be omitted and the expansion chamber employed alone, and the joint between the piston and cylinder of said chamber may be made tight by a close fit, or by providing a liquid or other suitable seal.

To automatically interrupt the circuit upon a relatively slight disturbance, for example, without delivering arc extinguishing liquid 46 to the point of interruption, relay 28 is adjusted as for example by adjustment of a spring for maintaining it open to close and thereby energize solenoid 22 and release catch 24; to permit spring 18 to open the switch upon a slighter disturbance than necessary to close relay 65. Relay 65 being adjusted to close upon a disturbance of greater severity, it will be apparent that upon the occurrence of such a disturbance, relays 28 and 65 are both closed to open the switch and simultaneously deliver are extinguishing liquid 46 through nozzle 35 to the point of interruption. In this manner the desirable properties of liquid 4-2 are taken advantage of wherever possible, and the liquid a6 with its better fire and arc extinguishing qualities is called into action only where necessary. If desired, the relays may of course be set to deliver arc extinguishing liquid whenever interruption occurs, and regardless of the severity of the disturbance.

In Figs. 2 and 3 the switch is shown mounted through a bracket member formed inte gral with cover 6 upon horizontal frame members 91 which are in turn secured to an upright frame member 92 extending up wardly from a base 93. Braces 9a are connected diagonally between base 93 and a lower horizontal frame member 95.

I do not intend to limit the invention to the details or to the particular embodiment oi? the essential features shown and described.

I claim:

1. In combination, a tank, a body of oil in the tank, circuit interrupting means submerged in the oil, abody of non-inflammable arcextinguishing liquid of different characteristics and greater arc-extinguishing ability than the oil, said liquid being contained outside of the tank, and means for injecting said non-inflammable arc-extinguishing liquid into the tank.

2. In combination an oil tank containing oil, a switch submerged in said oil, a reservoir for non-inflammable arc extinguishing liquid of different characteristics and greater insulating and are extinguishing properties than the oil, )ressure applying means for maintaining pressure upon said liquid, and means for injecting liquid from the reservoir into the tank when the switch is opened.

3. In combination a pair of switch contacts, a reservoir of arcextinguishing liquid, means for maintaining a body of arc-extinguishing gas under pressure in contact with the surface of the liquid in the reservoir for discharging the arc-extinguishing liquid to the switch contacts, means for conveying the liquid to the contacts and a valve for said liquid conveying means, and means operable by different abnormal circuit conditions for .zeparating the switch contacts and delivering the arc extinguishing liquid to the point of interruption.

4:. In combination, a. switch having separable contacts, a body of oil normally immersing said contacts and effective to extinguisli an arc therebetwee'n upon relatively light overload interruptions, a reservoir of arc extinguishing liquid, a body of arc extinguishing gas under pressure in contact with the liquid, for discharging the liquid between 5;;

the contacts when the switch is opened under heavier overload interrupting conditions, a valve for said liquid discharge means, and means for opening the switch and the valve together.

5. In combination a pair of switch contacts, a body of oil surrounding said contacts, a reservoir of arc-extinguishing liquid, a tank of compressed fluid connected to the reservoir, a nozzle for directing liquid upon the are between the contacts, said nozzle having connection with the reservoir, a valve in said connection, and means operable by different abnormal circuit conditions for separating the switch contacts and for delivering the arc extinguishing liquid to the point of interruption.

6. In combination, a pair of switch contacts, a reservoir of arc extinguishing liquid, a nozzle for directing the liquid upon the arc between the contacts, a tank of compressed gas connected to the reservoir for dischargthe liquid through said nozzle, said nozzle being connected to the reservoir, a valve for the nozzle, and electro-responsive means controlled by different abnormal circuit conditions for opening the switch first without opening said valve upon relatively light overload interruptions and the valve thereafter upon heavier overload circuit interruptions.

7. In combination, a pair of switch contacts, a body of oil normally surrounding said contacts, a reservoir of arc extinguishing liquid of greater arc extinguishing and insulating properties than the oil, pressure applying means for maintaining the liquid under pressure, and means for discharging said liquid into the space between the contacts when the contacts are separated.

8. In combination a tank containing oil, a pair of switch contacts in the oil, a nozzle directed across the space between the contacts when the contacts are separated, and across the paths of separation of the contacts, a tank for supplying an arc extinguishing medium ofdifferentcharacteristics and greater arc extinguishing and insulating properties than the oil to said nozzle and a valve controlling the discharge from the nozzle.

9. I11 combination an oil circuit breaker having an oil tank containing oil, means for injecting a non-inflammable arc-extinguishing liquid into the tank, means for opening the circuit breaker, and controlling means for operating both said means ointly or the latter means independently.

10. In a switch having separable contacts, liquid means normally active for extinguishing the are at said contacts, additional liquid means normally inactive for extinguisln ing said are and current controlled means for opening the switch without rendering said latter means active on light abnormal conditions, rendering said latter means active upon heavier abnormal conditions.

11.. In a device of the class described, current interrupting means, a bath therefor, means operable by an abnormal circuit condition for operating said interrupting means, and means operable by an abnormal circuit condition of greater severity for delivering an arc extinguishing liquid to the point of interruption.

12. In a device of the class described, a pair of circuit terminals, a bath therefor, means operable by excessive current for separating said terminals in said bath, and means operable by current in excess of that for operating said first means for delivering an arc extinguishing liquid to the point of interruption.

13. In a device of the class described, a pair of circuit terminals, a bath therefor, means operable by a relatively light over- 1 load for separating said terminals in said bath, and means operable with said first means by a heavier overload for delivering an arc extinguishing liquid to the point of interruption.

14:. In a device of the class described, the combination of a pair of circuit terminals, a bath therefor, means operable by an abnormal circuit condition for separating said terminals in said bath, an arc extinguishing liquid, means operable by an abnormal condition of greater severity for releasing said are extinguishing liquid, and fluid pressure means incapable of supporting combustion for delivering said are extinguishing liquid to the point of interruption upon release of said liquid.

15. In an electric switch, means controlled by abnormal electric circuit conditions for opening the switch, means for projecting a volatile insulating liquid into the region of the switch contacts for decreasing the arcing of the switch upon opening, said last means being normally ineffective, and means eifective if the abnormal conditions exceed a predetermined value for rendering the last named means eifective.

16. In an oil switch, electro-responsive means for measuring abnormal conditions in the circuit controlled by the switch, means controlled by the measuring means for opening the switch upon the occurrence of predetermined abnormal conditions, an insulating liquid of greater insulating qualities than the oil used, and means controlled by measuring means for delivering the liquid to the point of interruption of the contacts upon the occurrence of abnormal conditions of a greater degree than said predetermined conditions.

17. The method of operating a liquid imgreater insulating properties than that liquid. In witness whereof, I hereunto subscribe my name this 24th day of February, 1923. EDMUND O. SCHWEITZER.

Images