US2440484A - Voltage-limiting arc interrupter - Google Patents

Description

APlll 27,V 1948. R. R. PITTMAN VOLTAGE-LIMITING ARC INTERRUPTER Filed March 7, 1944 2 Sheets-Sheet l April 27, 1948. R, R, PITTMAN 2,440,484

VOLTAGE-LIMI TING ARC INTERRUPTER Filed March 7, 1944 2 Sheets-Sheet 2 INVENTOR Patented Apr. 27, 1948 a ED v 2,440,484-

voLrAGEL1MIT1NG ARC'INTERRUPTER Ralph armani-an, Lime Rock, Ark.

1944,.seria1. No. 525,465 2 claims. (ci. ris-so) Application March. 7,

This invention relates generally to discharge device constructions` for the purpose of limiting therise in voltage, such as might be caused by lightning or switching surges, ofV a connected conductor by meansof arcing gaps adapted to breakdown at a predeterminedvoltage, together withv means for quickly interrupting the passage of current. through4 the arcs` attending break down` of the gaps.

It has been generally` recognized that arcing gaps of the self-extinguishing type offer .the lbest means now known for dissipating extraneous or superimposed high voltages which appear in electric circuits. Such devices utilize gas evolvedby the 'heat of the arc to cause its extinguish-ment. The gas and flame discharged. from constructions now available is highly conducting, and this consideration has in many situations prevented Ythe use cf this otherwise desirable character of protection, for the reason that the discharged conducting gas may bridge contiguous live parts and thereby cause serious-damage to equipment So far as applicant has` been able to discover, no construction is now availablefor satisfactorily enclosing gas-evolvingarcing-gap mechanisms, so that no gas or llame is discharged when operat- 111g.

Among the objects-of. the present. invention may loe-noted the provision of means for completely enclosing a voltage-limitingv device of the gasdischarge type without adversely, affecting theY protective qualities or useful life of the device; the provision of an enclosed arc interrupter in whichl the space within an insulating housing is eiciently utilized to provide a small andinex-v pensive e construction; the provision of an arrangement forconning and quickly .cooling the incandescent gases evolved; and the provision of a simple structure in which several of the component elements perform two ormore necessary ordesirable functions. Other objects will be in part obvious, and in part pointed outlierein.- after.

The invention comprises the elements and combinations thereof, features of construction, and arrangement of parts to be exemplied in the description to follow, and the scope of the invention will be indicated in the accompanying claims.

In the drawings:- Fig. 1 is av sectional View illustrating the construction cf one complete device; and Fig. 2 .illustrates a series arrangementof several of the devices, for application to circuits higher in voltage thanv that for whicha single device may be suitable..

Similar reference characters indicate corref terial, I0, is'

sponding parts in the. several figures ofthe drawlng;`

Referring` in detail to the drawing, an upstandingY hollow cylindrical' housing, ofinsulating maprovided; at its. respective ends with rdly extending peripheral flanges [3' and may be conveniently secured' Vto the conducting material" H' is ttedover the upper end of the housing lll',v andrigidly'securedthereto Along a horizontal plane substantially below the upper closure Il, the partition I8` is extended inwardly and thence downwardly, terminating at an inwardly-turned integral'l Ilange within the lower portion ofthe housing LU. In this manner the ber'20, andthe exhaust The voltage-responsive arc-quenching device 22 is mounted, in spaced relationshipzwith =both the closures IlY and l2, on the inwardlyeturned flange of the partition I9, by means of theA mounting screws, 29, the latter exten-dingupwardly through the outwardly extendingll'ange of'the lower conducting electrode 25 of the'discharge device 22.

As illustrated, the discharge ydevice 22 is similar to, and described more indetail, in'U. S. Patent No. 2,164,720, dated `Julyl,v 1939,- and issued to Ralph R. Pittman. Suche.vr device use in the present invention",` but'fit will also be apparent that other voltage-responsive arcquenching construction might beV used.v

As shown in Fig. 1, the'discharge vdevice 22 includes the upstanding tubular insulator 23, and has secured thereto by-mea-ns offthreaded engagement at its respective ends, the upperconductingrelectrode 24 and the lower conducting electrode 25. The tubular insulator-23 contains the eccentrically mounted vfiller 21, also of insulating material. The lower electrode-251s provided with theupwardlyancrflntemally extendby cementing. An .upper closure ofv ing' extension 26, the arrangement being such that the weakest electrical path through the device is along the line of abutment of the ller 21 with the inner surface of the tubular insulator 23, and between the upper end of the electrode extension 26 and the upper electrode 24. Following sparkover of the weakest electrical path, any arc ensuing is driven around the ller 21, being concurrently moved laterally and elongated, and so cooled to facilitate extinguishment, The openings 28 through the lower electrode 25 vent the gaseous products attending the arc, and the device is economically constructed when the tubular insulator 23 and the filler 21 are formed of arcresponsive gas-evolving material; -ber.

The upper electrode 24 is preferably Y spaced from the lower surface of the'upper conducting closure ll to form the spark gap 33, so that under normal conditions the tubular insulator` 23 is not subjected to voltage stress.

To facilitate cooling of the incandescent gas discharged when the discharge device 22 operates, a 'discharge disperser or distributor formed as a cup provided with a large numb-er of small perforations 3i, is fitted over the vented en'd of the insulator 23, being held in position by means of the vmounting screw 32. Preferably the disperser is constructed of a material of good heat conductivity, ness of the'wall is of the order of three-eighths of one inch, so that the temperature of the gas discharged therefrom' is substantially reduced before reaching the exhaust chamber 2 l.

The conducting members embodied in the construction are so coordinated with the insulating members that the weakest electrical path from the upper terminal l'i to the lower terminal I8 is from the upper terminal il to the upper conducting closure Il; thence across the spark gap 33 to the upper electrode 2e, thence within the tubular insulator 23 .to the lower electrode Vextension 2S, thence to the lower electrode 25, thence through the conducting dividing wall I9 to the lower closure l2, and thence through the conducting base 34 to the lower terminal I8. Y

The partition i9 prevents contamination of the inner-surface oi the 'insulating housing 'I0 and thev outer surface of the tubular insulator 23, which would occur if the gas discharged from the discharge device 22 contacted the surfaces. A certain amount of incandescent-free carbon is often expelled from the discharge device, which, when deposited on the suriace of van insulator, provides a conducting layer. In addition to shieldingthe'insulating surfaces from contamination,`

the partition I9 also provides a support for the discharge device, and is so arranged that the inherent resiliency of the met-al from which the partition is formed absorbs the impact attending the operation of the discharge device. A further Vfunction of the partition l is to provide conducting means for connecting thelower electrode 25 to the lower conducting closure l2 vand the.

lower or ground terminal i3.

In certain-situations, it may to construct the interrupter in units suitable for a denite voltage rating, stacking the units in series,- circuit relation ier use en higher voltage circuits. Fig. 2 illustrates such a stacked arrangement, showing three units whicliare connected in series simply lby bolting the lower closure of one unit to the upper closure of another. Considerable economy results Vfrom the construction .ofqtheindividual units i such as hard such as copper, and the thick-V be economicalv for about ll kv.: op-.

closure to provide a spark 4 eration; the stacked arrangement illustrated would, under this condition, be suitable for application to a 33 kv. circuit.

It is intended that the description presented herein will be regarded as illustrative of the invention, rather than limiting.

I claim:

1. A voltage-limiting arc interrupter comprising a hollow cylindrical housing of insulating material having upper and lower closures of conducting material at its respective ends; a reentrant partition of conducting material extending within said housing, said partition engaging the lower closure and extending first inwardly and upwardly from the lower end of said housing to an elevation below that of the upper closure,

thence, inwardly and downwardly to a centrally positioned opening at an elevation above that of said lower closure; a discharge device including an upstanding tubular insulator closed at the upper end and vented at the lower end, normally insulated spaced upper and lower conducting electrodes associated therewith and so related that the weakest electrical path therebetween is within said insulator rather than externally thereof; means support-ing said discharge device on said partition at said last-named elevation, said discharge device extending upwardly in lateral spaced relationship with said partition and in vertical spaced relationship to the upper gap between the latter and the upper electrode of said discharge device, the lowerV end of said discharge device closing said centrally positioned opening and being arranged to vent gaseous products attending the operation of said discharge device only into the space between said lower closure and said reentrant partition; and a discharge disperser mounted at the vented end of said discharge device for cooling said gasous products prior to entry into said space; the conducting members being so related to the insulating housing that the weakest electrical path from said upper closure to said lower closure is via the series circuit arrangement of said spark gap and said discharge device.

2. A voltage-limiting arc interrupter comprising a hollow cylindrical housing of insulating material having upper and lower closures of conducting materialY at its respective ends; a reentrant partition of conducting material extending within said housing, said partition engaging the Vlower closure :and extendingrst inwardly andthence upwardly along and spaced from the inner surface of said housing, thence inwardly toward and spaced from the axis of said housing,v

and thence downwardly to an opening therein at an elevation abovethat of said lower closure; a discharge device including an upstanding tubular insulator closed at the upper end and vented at the lower end, normally insulated spaced upper and lower conducting electrodes Vassociated therewith and so related that the weakest electrical path therebetween is within said insulator rather than externally thereof; means supporting said discharge deviceron said partition at said lastnamed. elevation, said discharge device extending upwardly in lateral spaced relationship with said partition land in vertical spaced relationship to the upper closure to provide a spark gap between the latter andthe upper electrode of said dis-` of v said discharge reentrant partition; and a discharge disperser mounted at the vented end of said discharge device for cooling the gaseous products prior to entry into said space; the conducting members being so related to the insulating housing that the weakest electrical path from said upper closure to said lower closure is via the series circuit arrangement of said spark gap and said discharge device.

RALPH R. PI'ITMAN. REFERENCES CITED The following references are of record in the le of this patent:

Number 6 UNITED STATES PATENTS Name Date Atherton Dec. 6, 1927 Slepian Apr. 13, 1937 Rawlins June 1, 1937 Ackermann Mar. 17, 1942 Fitger June 2, 1942 Wade Mar. 20, 1945

Images