US2897324A - Fluid blast circuit interrupter - Google Patents

Description

y 1959 H. N. SCHNEIDER 2,897,324

FLUID BLAST CIRCUIT INTERRUPTER Filed Oct. 9, 195'? Inventor:

I Harold N. Sc -rweiciexr,

by m His I ttorney.

United States Patent FLUID BLAST CIRCUIT INTERRUPTER Harold N. Schneiden Spi'ingfield;Pa., as'signor to General Electric Companyya' corp'oration' of New York Application October 9, .1957, Serial No. 689,122

7 Claims. =(Cl. 203- 148) This invention relatesto a'circuiti interrupter which relies upon a fluid blast for extinguishing a circuit-interrupting arc and, more particularly, to an arrangement for holding the arc in a desired position for eflicient interruption and for preventing the fluidblast fromdriving the are into a position where the varc might damage relatively vulnerable parts of the interrupter.

-In many fluid blast circuit interrupters, the are extinguishing blast which is directed into the arc tends to drive one terminal of the are considerable distances downstream from its original position. If the displaced arc terminal happens to be driven into proximity with a relatively vulnerable part of the interrupter, the arc can, of course, cause material damage to the interrupter.

This problem is of particular importance in the pressurized type of interrupter which has its blast-controlling valve located downstream from the arcing contacts of the interrupter. In such designs, if the arc terminal happens to be driven onto the blast valve, the blast valve could be damaged and the operation of theinterrupter, thus, impaired.

For limiting the movement of an arc terminal, it has been customary to provide a downstream probe to which the arc terminal can readily attach. Prior probes, however, have not been entirely reliable in preventing the fluid blast from driving the arc terminal off of the probe and further downstream.

Accordingly, an object of my invention is to provide a downstream probe which is highly effective in anchoring the arc terminal in position against the on-rushing fluid blast.

In carrying out my invention inone form, I provide a fluid blast circuit interrupter which'has a'pair of separable contacts for establishing a circuit-interrupting arc. For extinguishing the arc, a blast of fluid is directed into the arc, and this blast is exhausted through a conductive exhaust member defining an exhaust passage downstream from said arc. Projecting from a wallof said passageway transversely into the path of said blast is a conductive probe of arc-resistant material. The probe has an upstream surface of a non-streamlined configuration for coacting with said blast to form upstream from said surface a stagnation region of sufficient volume to encompass a substantial portion of a terminal of the arc. When the blast, during the arc-extinguishing process, acts to drive the are into the region of the probe, one terminal of the arc is captured Within this stagnation region and further downstream motion of the terminal is thereby prevented.

For a better understanding of my invention reference may be had to the following specification taken in conjunction with the accompanying drawing wherein:

Fig. 1 is a cross-sectional view of a fluid blast circuit interrupter embodying my invention.

Fig. 2 is an enlarged perspective view of one of the components of Fig. 1, and

Fig. 3 is an enlarged side elevational view of the components shown in Fig. 2.

2,897,324 Patented July 28, 1959 Referring now'to Fig. 1,t-he circuit interrupter-shown therein is of the"sustained-pressure, ga's blast 'type described and claimed in US. Patent No. 2,783,338, -Beatty, assigned-to the assignee ofthe present invention. Oniy those parts'of the Beatty interrupter which are considered necessary'to provide anunderstanding of the present-invention have been shown in Fig. 1. In this regard, only the top portion of 'the'interrupter has been showninasmuch as the interrupter is generally symmetrical with respect to a horizontal plane and the bottom portion is substantially'identical to the top portion. As described in detail in-the Beatty patent, the interrupter comprises a casing'12 which isnormallyfilled with pressurized gas to define aninterruptingchamber 11. Located within the interrupting chamber 11 are a pair of relatively movable contacts 14 and '16 which can be separated to draw a circuit-interruptingarc within the pressurized gasof the chamber 11. The contact 14 is relatively stationary, whereas the other contact 16' is mounted for pivotal movement about a fixed'current-carrying pivot 18. Wheat-he contact '16 is driven counterclockwise about the'pivot 18, an arc is established intheregion where the contacts'pa'rt. The movable contact 16 is shown in'Fig. 1 inapartially open position through which it passesduring a circuitinterrupting operation.

The movable contact 16 issupportedby means-of its current carrying pivot '18 on a conductive bracket 19 which is preferably formed' integral "with a stationary cylinder 32. The cylinder 32' at its left hand "endis suitably supported from' a'generally cylindrical casting 33. The casting 33 at its left' hand end has an annular-flange 34 suitably secured to' a mating flange 35 rigidly carried by the stationary metallic casing 12.

"For producing a gas' blast to aidin extinguishing the arc, the cylindrical casting'33 contains a normally clos'ed exhaust passageway '36'leading from"the interrupting chamber 11 to'the surrounding atmosphere. The exhaust member 33 at its right hand end is provided with a nozzle type electrode 38 defining an inlet orifice tothe exhaust passage 36. The'flow of 'arc-extinguishinggas"through the nozzle electrode 38 and the exhaust passage 36 is'controlled bymeans of a cylindricallyeshaped reciprocable blast valve member40 located at the outer end of the exhaust passage 36. Thisblast valve"member"40'normally occupies a closed position wherein an annular flange 42 formed at its" left hand end :se'alin'gly abuts against the stationary flange 34, which serves as a'valve seat. In the position of 'Fig. 1, however, the valve mem ber 40 is shown in a' partially open position through which it passes during a circuit-interruptingoperation. Opening of the valve member 40 allows pressurized gas in the chamber 11 to flow at high speed through the nozzle 38 and out the passageway 36 past the valve. member 40 to atmosphere, as indicated by the arrows in Fig. 1. The manner in which this gas blast acts to extinguish the arc will soon be described in greater detail.

At its right hand end, the cylindrical valve member 40 surrounds a projecting support v41 upon which the valve member 40 is smoothly slidable. This support 41 is shown formed-integral with the casting 33. A compression .spring44positioned.between the valve member 41) and the support 41 tends to hold the valve member' ltl in its closed position against the flange 34.

.To protect the support 41 and the right hand end of the valve member-40 from the harmful effects of arcing, a protective metallic tube43 is positioned about these parts and is secured to'the support 41 by suitable fastening means, such as 44a. Secured to "the outer surface of this tube 43 is a probe 45 which projects radially from the tube 43. and transversely into the path of the fluid blast. flowing through the passageway 36. As .will

'soon appear more clearly, the lower terminal of the arc is transferred to this probe 45, and, for this reason, the probe is preferably composed of a refractory conductive material which is highly resistant to arcing. Preferably, the probe comprises a base portion 46 which is formed integral with a body portion 47 of the probe. The upstream surface 48 of the probe faces the fluid blast and is of a non-streamlined configuration with respect to the fluid blast and, as a result, coacts with the blast to form a relatively large stagnation region 49 upstream from the surface 48. The stagnation region 49 is best shown in Fig. 3 where the streamlines representing the approximate flow pattern past the probe are shown. The innermost streamline is spaced by an appreciable distance from the adjacent surfaces of the probe, and this intervening space constitutes the stagnation region. In this region of stagnation, most of the flow which is present is believed to be in the form of eddies having little or no velocity in the general direction of the fluid blast. The manner in which this stagnation region is utilized will soon appear more clearly.

For controlling the operation of the blast valve 40 and the movable contact 16, a combined operating mechanism 50 is provided. This mechanism 50 is preferably constructed in the manner disclosed and claimed in the aforementioned Beatty patent, and its details form no part of the present invention. Generally speaking, this mechanism 50 comprises a valve-controlling piston 51 and a contact-controlling piston 52 mounted within the cylinder 32. The valve-controlling piston 51 is coupled to the valve member 40 through a piston rod 54 suitably clamped to the valve member 40. The contact-controlling piston 52, on the other hand, is connected to the movable contact 16 through a piston rod 58 and a cross head 59 secured to the piston rod. A link 60 pivotally joined to the cross head at 61 and to the movable contact at 62 interconnects the cross head and the movable contacts 16. When the valve-controlling piston 51 is driven to the right, it acts to open the valve member 40 and, simultaneously, to drive the contact-controlling piston 52 to the right to produce opening movement of the contact member 16.

Opening movement of the contact member 16 first establishes an are between the ends of contacts 14 and 16. The blast of air which is flowing through the nozzle 38, however, quickly forces the upper terminal of the arc on to an arcing electrode 70, which is electrically connected to the stationary contact 14. As opening motion of the movable contact 16 continues, the gas blast forces the lower terminal of the arc to transfer from the contact 16 to the orifice of nozzle 33 and then impels this lower terminal into the orifice and on to the right hand end of the protective tube 43. From there, the fluid blast drives the lower arc terminal to the left and into the previously described stagnation region 49 adjacent the non-streamlined upstream surface 48.

In accordance with my invention, this upstream surface 48 is of such a size and configuration that the stagnation region 49 is of suflicient volume to encompass a substantial, and preferably a major, portion of the arc terminal. As a result, the arc terminal is, in effect, shielded from the high velocity flow of the fluid blast and remains effectively anchored to the probe within the stagnation region in spite of the blast. The approximate position of the arc during this interval is shown at 71 in Fig. 1. When the arc has moved into this approximate position, the action of the gas blast becomes effective to deionize and extinguish the arc, thereby interrupting the circuit. The position of the probe is so selected that the are, when attached to the probe, is subjected to a cross-blast, as well as an axial blast, and this materially facilitates the interrupting process. In this regard, note particularly that the portion of the are which is located adjacent the probe is disposed transverse to the general direction of the blast flowing through the ,4 nozzle 38. Additionally, the position selected for the probe is such as to provide a minimum length of are consistent with preserving the desired flow pattern through the orifice of the nozzle 38 and with respect to the arc itself.

Since the probe acts, as above-described, to prevent the arc terminal from being driven further downstream, the possibility that the arc will be driven into proximity with the blast valve 40 is effectively prevented. Correspondingly, the possibility that the blast valve will be damaged by the arc and the operation of the interrupter thereby impaired is effectively prevented.

Although I have shown the upstream surface 48 as being of a planar configuration disposed generally perpendicular to the direction of the blast, it will be apparent that certain minor variations can be made in the nonstreamlined configuration of the surface. For example, this surface can be slightly concave with respect to the direction of the blast. In any case, however, the surface should be of a non-streamlined configuration and capable of producing a stagnation region of suflicient volume to encompass a substantial and preferably a major portion of the arc terminal. Streamlined upstream surfaces, such as those of a rounded configuration, convex with respect to the direction of the blast, have been found ineffective to provide such a stagnation region.

The purpose of the base portion 46 of the probe is to provide arc-resistant material in the immediate vicinity of the anchored arc terminal so as to prevent the are from causing any damage in this region. The upper surface of this base portion is transversely-disposed with respect to the position occupied by the axis of the lower portion of the are when the arc terminal is located within the stagnation region 49. Preferably, the base 46 has its upstream end tapered at 65 so as to facilitate movement of the arc terminal on to the probe and to prevent retardation in the motion of the terminal just ahead of this point.

With respect to the arcing electrode 70 for the upper arc terminal, it will be noted that a centrally-disposed passageway 72 is provided therein. One of the purposes of this passageway is to encourage motion of the upper arc-terminal on this electrode by denying the arc terminal a possibly-stable footing at the center of the electrode. This materially aids in reducing erosion of the electrode 70 due to arcing.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects and I, therefore, intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a fluid blast circuit interrupter, a pair of separable contacts for establishing a circuit-interrupting are, means for causing a blast of arc-extinguishing fluid to be directed into said arc, a conductive exhaust member electrically connected to one of said contacts and defining downstream from said are a passageway for said fluid blast, a conductive probe of arc-resistant refractory material projecting from a wall of said passageway transversely into the path of fluid flowing through said passageway, said probe having an upstream surface of nonstreamlined configuration facing the fluid blast for coacting with said fluid blast to form upstream from said surface a stagnation region of suflicient volume to encompass a substantial portion of the terminal of said arc, said fluid blast acting to drive one terminal of said are from one of said contacts onto said probe and into captured relationship within said stagnation region.

2. The fluid blast circuit interrupter of claim 1 in which said probe is so located that when said arc terminal is captured within said stagnation region, the portion of 0 said arc adjacent said probe is subjected to a cross-blast by said fluid blast.

3. The combination of claim 1 in which said probe also comprises a base portion having a surface extending upstream from said upstream surface transverse to the axis of an adjacent portion of said are when the arc terminal is located within said stagnation region.

4. In a fluid blast circuit interrupter, a pair of separable contacts for establishing a circuit-interrupting arc, means for causing a blast of arc-extinguishing fluid to be directed into said arc, a conductive exhaust member electrically connected to one of said contacts and defining downstream from said are a passageway for said fluid blast, a conductive probe of arc-resistant refractory material projecting from a wall of said passageway transversely into the path of fluid flowing through said passageway, said probe having a generally planar upstream surface disposed generally perpendicular to the direction of said blast in the immediate region of said surface for coacting with said blast to form thereadjacent a region of low velocity in comparison to the blast velocity, said blast acting to drive one terminal portion of said are from one of said contacts onto said probe and into captured relationship within said region of low velocity.

5. In a fluid blast circuit breaker, means forming a pressurized interrupting chamber, a pair of separable contacts mounted in said chamber for establishing a circuitinterrupting are, a conductive exhaust member electrically connected to one of said contacts and defining a passageway leading from the region of said contacts to a low pressure region outside of said interrupting chamber,

means including a movable blast valve member located within said passageway downstream from said contacts for producing a fluid blast through said passageway upon opening of said valve member, a protective tube surrounding said movable blast valve member at an upstream side thereof and forming a wall of said passageway, a conductive probe of are resistant material projecting from said tube transversely into the path of fluid flowing through said passageway, said probe having an upstream surface of non-streamline configuration facing said fluid blast for coacting with said fluid blast to form upstream from said surface a stagnation region of sufficient volume to encompass a substantial portion of a terminal of said arc, said fluid blast acting to drive one terminal of said arc onto said probe and into captured relationship within said stagnation region.

6. The combination of claim 5 in which said upstream surface is of a generally planar configuration and is disposed generally perpendicular to the direction of said blast.

7. The combination of claim 5 in which said probe also comprises a base portion having a surface extending upstream from said upstream surface transversely with respect to the axis of an adjacent portion of said are when the arc terminal is located within said stagnation region.

References Cited in the file of this patent UNITED STATES PATENTS 2,570,610 Taylor Oct. 9, 1951 2,574,334 Latour Nov. 6, 1951 2,783,338 Beatty Feb. 26, 1957

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