US2521155A - High-voltage circuit interrupter - Google Patents

Description

Sept. 5, 1950 R. H. EARLE ETAL HIGH-VOLTAGE cmcun INTERRUPTER Original Filed Jan. 29, 1944 2 Sheets-Sheet 1 ATTOIPMEX Sept. 5, 1950 R. H. EARLE ETAL HIGH-VOLTAGE CIRCUIT INTERRUPTER Original Filed Jan. 29, 1944 2 Sheets-Sheet 2 A M 5 Wm m 1%) Patented Sept. 5, 1950 2,521,155 I HIGH-VOLTAGE CIRCUIT INTERRUPTER Ralph H. Earle, Wauwatosa, and Roald H.

Amundson, Milwaukee, Wis., assignors to Me- Graw Electric Company, a corporation of Delaware Original applicationJanuary 29, 1944, Serial No.

520,180, now Patent No. 2,459,691, dated January 18, 1949. Divided and this application January 4, 1947, Serial No. 720,184

This invention relates to high voltage circuit interrupters.

This application is a division of our copending application, Serial No. 520,180, for High Voltage Circuit Interrupters, filed January 29, 1944. Said copending application has resulted in Patent No. 2,459,691, dated Jan. 18, 1949.

Objects of this invention are to provide an interrupter which is capable of interrupting high voltage, heavy duty circuits and which rapidly extinguishes the resulting arc in an eiiective and reliable manner.

Further objects are to provide a high voltage, heavy duty, drop-out circuit interrupter in which meansare employed,such as a tube for instance, which providesan arc channel with a fusible link located in the arc channel, and'to provide means for extending the arc incident to rupture of the Iuselink on overload and for drawing the arc into proximity to material adapted to evolve or liberate gas when acted upon by an arc to thereby produce a blast of gas axially of the arc channel to extinguish the arc, the construction being such that after the circuit has been interrupted within the arc channel the device drops out of circuit to an inoperative position.

Further objects are to provide a circuit interrupter whichis so constructed that it will effectively interrupt the circuit for a relativel small overload or for a relatively large overload or for any intermediate value of overload with equal certainty of operation in each case, and'which is so made that the building up of excessive pressure in the arc channel is prevented.

In greater detail, further objects of this invention are to provide a high voltage, heavy duty fuse construction in which an expellable apertured plug is provided through which a blast of gas is projected to extinguish the are upon rupture of the fuse link on moderate overloads with the plug so arranged that it is expelled on heavy overloads to provide a larger discharge passageway for the gas to thereby prevent the building up of excessive pressure in the device.

Further objects are to provide a fuse construc- 'tion in which a blast of gas is employed for extinguishing the arc, in which plunger or other means withdrawn inwardly of a fuse tube by spring means is employed for leading the are into proximity to material adapted to evolve gas when acted upon by an arc, means being provided for definitely limiting the travel of the plunger or other means to a predetermined length of path, the construction being such that thespring means is housed with a tube and is 2 Claims. (01. 200-420) protected from the arc and from any gas incident to the arc.

Further objects are to so construct the interrupter that renewal or refill units carrying material adapted to evolve gas when acted upon'by an arc may be substituted for the used units so that the major portion of the interrupter may be used over and over again,

An embodiment of the invention is shown in the accompanying drawings, in which: I

Figure 1 is a side elevation showing the apparatus, such view showing the interrupter in circuit closed or operative position.

Figure 2 is a view of a fuse tube, partly broken away and partly in section.

Figure 3 is a view from the lower side of the member to which the lower end of the retracting spring of Figure 2 is attached. 1 Referring to Figure 1, it will be seen that the device comprises upper and lower stationary terminals indicated generally by the reference characters I and 2 which are carried by suitable insulators? and 4, respectively, which in turn are supported from a suitable supporting member 51 A fuse tube I00 is pivotally supported from the lower terminal 2 and is provided with" an'upper terminal IOI having outwardly projecting members or pins I03 on oppositesides thereofand having a threaded metal cap I02. The upper stationary terminal I may be constructed as set'forthin detail in the patent to William O. Schultz, No. 2,357,772 of September 5, 1944 for Cut-Out Construction, and'maycom prise' a pair of spring arms 0 which are pivotally supported bya stationary member I0 and bear against oppositely disposed, downwardly slanting'cam portions II forming aportion of the stationary member Ill. The spring arms are providedwith downwardly depressedportions I2 and with outwardly and upwardly slanting guiding portions I3. Normally the projections I03 of the'terminal IOI of the fuse tube are hooked behind "the downwardly depressed portions I2 of the "spring arms 0. The lower stationary terminal '2 may be formed in the manner of a housing as indicated and may be provided with apair of hook-like supporting portions I4. The lower stationary terminal also includes a relatively heavy contact spring I5.

:Thefuse tube I00 has a uniform bore I04 throughout its major portion. The lower portion of the bore, however, is enlarged as indicated at I05 and terminates in a shoulder I06. Within the enlarged portion I05 of the bore a fiber tube I01 is positioned. This fiber tube is rigidly carried by means of a metal sleeve I08 which has a portion spun into interlocking engagement with the fiber sleeve. The metal sleeve I08 is provided with a flange I09 which is seated against the lower end of the tube I00. It is held in place by means of a threaded metal nut IIO. Within the lower end of the metal sleeve I08 a metal cap I I I is slidably positioned. It is preferably provided with a plurality of resilient fingers I I2 separated by slots. It is connected by means of a flexible leader II3 with a fuse link extracting lever II4, the leader I I3 being held in place by means of a thumb nut H5. The lever H4 is provided with a rounded lower portion IIB beneath which the leader II3 passes.

The lever II4 has a pair of rearwardly projecting arms which are provided with trunnions II I adapted to seat within the hook-like supports I4 of Figure 1. It has a rearwardly projecting portion II3 adapted to engage the lower contact spring I5 of Figure 1. The lower end of the fuse tube is rigidly attached to a sleeve like member II9 which is provided with a rearwardly projecting arm I20 pivoted as indicated at I2I to the main lever II4. It is apparent, therefore, that when the fuse link is ruptured, the main lever I I4 moves downwardly and moves the lower end of the fuse tube I downwardly and outwardly allowing the upper end to detach itself from the sprin arms of the upper stationary contact, the fuse tube thereafter executing drop-out motion.

The fiber sleeve I01 carries an elongated, torusshaped, hermetically sealed container I22 of glass or other suitable material within which material such as a liquid I23 is carried, the material being adapted to evolve gas when acted upon by an arc, the arc rupturing the container I22. The liquid may be carbon tetrachloride, methylene chloride or chloroform, or any other suitable material. The upper end of the tube I01 is closed by means of a screw threaded apertured plug I24. The lower end of the fiber sleeve or tube I01 receives the threaded fiber sleeve I25. Between the container I22 and the sleeve I25 and the plug I24 cork or similar washers are positioned as indicated in Figure 2.

The fiber sleeve I25 carries the expellable plug I20 of fiber which has a reduced portion out of contact with the sleeve I25 and an enlarged portion slidably held within the sleeve so as to allow the plug I26 to be blown from the fiber sleeve under very heavy overloads.

A rectractable plunger I21 freely passes through the container I22 and through the plugs I26 and I24. Its lower end is attached to the flexible leader H3 and the metal cap III by means of a strain wire I28 and a fusible section I29. Thus it will be seen that the fuse link includes a fusible section and a retractable section or plunger. The upper end of the retractable metal plunger I21 is threaded and is received within a fitting or head I30. This head is provided with a flange I3I integral or otherwise rigidly secured thereto. The fiange approximately fits the larger bore I and is adapted to freely slide upwardly in a manner hereinafter to be described upon rupture of the fuse link. It is brought to rest, however, when it engages the shouldered portion I00 and thus forms a means for definitely arresting the upward motion of the plunger I21 so that the lower end of the plunger I21 never passes through the plug I24.

A tension spring I32 has its lower end secured to the head I30 and its upper end secured to the uppershead I33. The lower head [30 and the upper head I33 are also electrically connected by means of the flexible leader I34. The upper head I 33 is provided with a reduced externally and internally threaded portion I35 and receives the internally screw threaded metal washer I36. The metal washer I36 is rigidly clamped against the upper terminal IOI by means of the metal screw cap I02.

The fiber sleeve I01 together with the container I 22 and the associated parts including the metal cap I II and the flexible leader II3 constitute a refill unit and it is to be noted that the refill unit may be easily attached to the lower head I30 by screwing the upper end of the retractable plunger I21 into the internally threaded lower head I30. In order to keep the plunger I 21 from turning with reference to the sleeve I01 during this operation, it is provided with a transverse pin I31 which seats within a slot formed in the upper portion of the plug I24.

When an overload of, moderate magnitude occurs, the fusible section I29 and the strain wire I28 are ruptured and the retractable plunger I21 is quickly drawn upwardly by means of the spring I 32, thus leading the are into proximity to the gas evolving material I23 and rupturing the container I22. A violent blast of arcextinguishing gases is generated and blows outwardly through the restricted aperture in the expellable plug I26 and extinguishes the arc. The main lever II4 rocks downwardly and moves the lower end of the fuse tube downwardly and outwardly and allows the fuse tube to drop out of position as hereinbefore described. It is to be noted particularly that the upward stroke of the retractable plunger is definitely limited by the stop means provided by the flange I3! and the shoulder I06. It is preferable to rovide cut-outs I38 in the flange I3I to allow free passage of air and to prevent retardation of the upward motion of the plunger I21.

If a heavy overload had occurred, the operation is the same as hereinabove described except for the fact that the expellable plug I26 is blown out from the lower end of the tube [25 and a larger aperture is provided for the discharge of gases. This prevents the building up of excessive pressure within the device even under very heavy overloads.

It is to be understood that the cork washers on opposite sides of the container are merely cushioning washers and are very thin and are immediately destroyed or blown outwardly during the operation of the apparatus under overload.

The reason for detachably coupling the upper head I33 with the metal washer I36 is to facilitate reloading of the device.

In re-fusing thedevice, the operator removes the cap I02 and unscrews the washer I35 from the upper head I33. Thereafter the operator unscrews the old rod I21 from the head I30 and the refill unit is thereafter attached to the lower head I30 by screwing the rod I21 of the new unit into the lower head I30. Thereafter the operator screws the lower end of a threaded rod, not

-'= shown, into the internally threaded portion of the reduced part I35 of the upper head I33 and passes this rod upwardly through the fuse tube and passes the rod through the metal washer I36. He then draws the rod upwardly and as soon as the flange I09 of the refill unit is seated against the lower end of the fuse tube I00, he continues drawing the rod upwardly and thus extends the spring I32. When he has drawn the upper portion I35 of the upper head I33 slightly above the upper end of the fuse tube, 'he screws the metal Washer I36 onto the reduced portion B5 and allows the washer I36 to come to rest against the upper terminal |l of the fuse tube. Thereafter he replaces the threaded cap IE2 at the upper end of the fuse tube and the nut H0 at the lower end of the fuse tube. He then attaches the flexible leader to the lever 4' by means of the thumb nut H5 and the device is then ready to be repositioned and rocked back into operative position.

It is to be noted that the drop-out fuse tube is adapted to be removed and repositioned by means of a switch stick and after being repositioned is rocked into operative position by means of the switch stick.

It is apparent that the fuse tube may be made of fiber or may be made of Bakelite lined with fiber in a well known manner.

It will be seen that this invention provides a novel form of high voltage, heavy duty circuit interrupter in which provision is made for caring for both heavy and light overloads and for overloads of all intermediate values. Under a light overload a relatively restricted passage is provided for the blast of arc extinguishing gas, whereas for a relatively heavy overload the expellable plug is expelled and a larger passage is provided for the blast of arc extinguishing gases. In this manner excessive building up of pressure internally of the device is prevented.

It is to be noted that the fuse link is a composite structure and in the form shown consists of the fusible section, the strain wire, the retractable plunger and the flexible leader It is to be noted that the fuse tube has an arc channel therethrough which is divided into two portions, in one of which the blast of are extinguishing gas is produced. The other portion of the arc channel provides a part into which a portion of the fuse link is retracted.

It is to be noted also that the major portion of the device is used over and over and refill units are supplied the user so that he may install the refill units without returning the tube to the factory.

It is to be noted that the fusible section of the fuse link is kept in spaced relation to the gas liberating material. It is to be noted that the fuse link heats up to a considerable degree when it is carrying somewhere near its full rated load. By having the fusible section spaced from the gas liberating means, there is less chance of rupturing the container carrying the gas liberating means than if the fusible section of the fuse link was in contact with or immediately adjacent the container of the gas liberating means.

It is to be understood that where it is stated in the description or claims that the fusible section of the fuse link is spaced from the gas liberating means, it is intended to mean that the fusible section is not surrounded by the gas libcrating means or adjacent the gas liberating means, but is actually spaced therefrom.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

We claim:

1. A circuit interrupter comprising a body portion provided with a channel; a renewable refill unit adapted to be positioned in said channel and comprising a sleeve, retractable plunger, a fusible member connected to said plunger, an expellable apertured plug carried by said sleeve and adapted to be blown therefrom on heavy overloads and surrounding said plunger and spaced from said fusible member, and gas liberating means spaced from said fusible member and surrounding only said plunger and located in said sleeve and adapted to liberate gas when acted upon by the arc incident to blowing of the fusible member; and spring retracting means within the channel of said body portion detachably connected to said plunger.

2. A circuit interrupter comprising a. tubular body portion having a closed upper end and an open lower end; a renewable refill unit adapted to be positioned in said tubular body portion adjacent the open end and comprising a sleeve, a retractable plunger, a, fusible member connected to said plunger, an expellable apertured plug carried by said sleeve and adapted to be blown therefrom and through the open lower end of said tubular body portion on heavy overloads and surrounding said plunger and spaced from said fusible member, and gas liberating means spaced from said fusible member and surrounding only said plunger and located in said sleeve and adapted to liberate gas when acted upon by the arc incident to blowing of the fusible member, and spring retracting means within the channel of said body portion detachably connected to said plunger.

RALPH H. E ARLE. ROALD H. AMUNDSON.

REFERENCES CITED The "following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,614,014 Murray Jan. 11, 1927 2,091,424 Triplett Aug. 31, 1937 2,091,430 Conrad Aug. 31, 1937 2,179,342 Muller Nov. '7, 1939 2,226,838 Triplett Dec. 31, 1940 2,285,602 McMahon June 9, 1942 2,319,276 Triplett May 18, 1943 2,353,528 Triplett July 11, 1944

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