US3816684A - Blast nozzle units with radial holes for self-blasting compressed gas electric circuit-breakers - Google Patents

Blast nozzle units with radial holes for self-blasting compressed gas electric circuit-breakers Download PDF

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Publication number
US3816684A
US3816684A US00275219A US27521972A US3816684A US 3816684 A US3816684 A US 3816684A US 00275219 A US00275219 A US 00275219A US 27521972 A US27521972 A US 27521972A US 3816684 A US3816684 A US 3816684A
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United States
Prior art keywords
zone
nozzle assembly
assembly according
section
grooves
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Expired - Lifetime
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US00275219A
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English (en)
Inventor
B Teijeiro
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Magrini Fabbriche Riunite Magrini Scarpa e Magnano MSM SpA
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Magrini Fabbriche Riunite Magrini Scarpa e Magnano MSM SpA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/70—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid
    • H01H33/7015—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid characterised by flow directing elements associated with contacts
    • H01H33/7023—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid characterised by flow directing elements associated with contacts characterised by an insulating tubular gas flow enhancing nozzle
    • H01H33/703—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid characterised by flow directing elements associated with contacts characterised by an insulating tubular gas flow enhancing nozzle having special gas flow directing elements, e.g. grooves, extensions

Definitions

  • the intermediate section has radial holes, the mouths of which open into the gas flow stream and the outlet section has a plurality of annular rings of triangular cross-section, the cross-sectional areas decreasing and the spacing between adjacent rings increasing in a downstream direction of the outlet section.
  • interruption-chambers internally shaped in such a way to present, in the direction of the quenching gas outflow, an initial convergent zone, an intermediate zone having the smallest section, and an end divergent zone.
  • the intermediate zone of smallest section may be either shaped only as an area of the plane defined by the intersection of the initial convergent zone with the end divergent zone or it may assume a cylindrical shape. In the latter case, said zone has a determined axial development and it constitutes the fillet length between the initial convergent and the end divergent zones, which are kept spaced from each other by the intermediate cylindrical zone of smallest section.
  • holes are formed in with the zone of smallest section, which holes pass radially through the wall of the interruption-chamber in the transverse direction with respect to the central longitudinal axis of the chamber; these holes promote the decompression of the interruption-chamber part placed downstream of the first (convergent) zone. More particularly, the holes are located in the initial part of the third (divergent) zone immediately downstream of the second (smallest) zone when the latter is constituted only by a plane as previously described; on the contrary, they are located in the zone of smallest section when this one has a cylindrical shape and a non-zero axial development.
  • a further known characteristic of such compressed gas interruption-chambers is the presence of annular channels or grooves formed on the wall of the divergent zone, which also constitutes the end part of the chamber. These grooves are provided for the purpose of increasing the streamline of the quenching gases through the chamber.
  • annular or ring-like grooves of previous interruption chambers have all been formed of a rectangular or similar diametral cross-section, all of the circular grooves having the same cross-sectional dimension.
  • the object of this invention is therefore the construction of an interruption-chamber for compressed gas circuit-breakers structurally improved with respect to the prior art technique and in particular with respect to the interruption-chambers with radial holes.
  • a further object of this invention is to provide an interruption-chamber for electric circuit-breakers having improved decompression of the smallest sectioned intermediate zone to aid in the escape of quenching gas through holes machined radially in the walls of the intermediate section.
  • a further object of this invention is to improve the interruption-chambers in such a way that the ring-like grooves formed on the inner walls of the interruptionchambers assist in directing the discharge flow of the quenching gases.
  • a still further object of the present invention is an axial blast interruption-chamber combining the effects of quick decompression in the inlet zone of the radial holes and optimization of the flow of the decompression gases and the quenching gas through the downstream part of the chamber itself, consequently accelerating the outflow of the whole of these gases through the outlet orifice of the chamber and decreasing the whirl effects occurring in the total outflow, thereby greatly improving the performance of the interruptionchamber.
  • an axial blast interruption-chamber for self-blasting compressed gas electric circuit-breakers especially circuit-breakers in which sulphur hexafluoride gas is used as the electric arc quenching fluid, having a blast nozzle structure, with radial holes, internally shaped to provide in the outlet direction a first substantially conical and convergent zone, a second intermediate zone of smaller section with respect to the other internal zones, and a third substantially conical and divergent zone.
  • the latter zone has a length L determined by the known experimental relation, L B U,,/ 3 (1.5) V7;
  • the intermediate zone of smallest section is substantially a convergent truncated cone zone with a very small tapering angle, the usual decompression holes being formed through the same second or intermediate zone, their mouth sections being inclined by an angle with respect to the chamber axis and, consequently, also with respect to the lines of the quenching gas flow; the mouth sections are also formed to be directed towards the interruption-chamber inlet.
  • a plurality of annular grooves are formed downstream of the intermediate truncated-cone zone, the diametral crosssection of the grooves being substantially triangular shaped with a vertex angle defined by the meeting of two surfaces, one of the surfaces being substantially perpendicular to the axis of the chamber itself, and having an open base faced towards the outlet orifice of the interruption-chamber, namely directed in way to favor the escape of the decomposition gases along a direction concomitant with the direction of flow of the quenching gas stream; the dimensions of the substantially triangular diametral cross-section of each annular or ring-like groove decrease little by little from the first groove, immediately downstream the intermediate zone, to the last groove closer to the chamber outlet, with the distance between adjacent grooves increasing among successive grooves in the direction of the chamber outlet.
  • FIGURE representing, in a schematic form and according to a longitudinal section, the nozzle unit with radial holes which is the subject of the present invention.
  • the improved nozzle unit with radial holes of the present invention has a substantially truncated cone shaped intermediate zone 5, convergent towards the outlet 2 of the interruptionchamber and having a very limited cone-shape, the angle 20: which defines the cone-shape having values ranging from 2 to 10, but preferably having value of 4.
  • Zone 5 has decompression holes 6 located therein.
  • an attraction zone is formed which facilitates the entry of a part of the flow 7 into the holes 6 (see arrows 8) to assure the quickest possible decompression of the zone 5, without, at the same time, giving rise in the same zone to a depression such as to introduce a gas suction from the outside through the holes 6, with the negative consequences which have already been discussed above.
  • the intermediate zone 5 remains substantially the zone of smaller section with respect to the other two zones, namely the upstream zone (zone I) and the downstream zone (zone 9); it is noted, however, that the smallest cross-section of the zone 5 is that one lying in the plane (perpendicular to the plane of the drawing) indicated by the line XX and defined by the intersection of the intermediate zone 5 itself (which is slightly convergent towards the nozzle outlet 2) with the end zone 9 which is conical and divergent.
  • a series of ring-like grooves 13 are machined in the internal wall of divergent zone 9.
  • the grooves 13 have a substantially triangular diametral cross-section and a width and depth which decrease gradually from the first groove, immediately downstream the intermediate zone 5, to the last groove closer to the chamber outlet 2; furthermore, of the two sides of the triangular section formed by the wall of the chamber (wherein the grooves have been formed), one lies in a plane substantially perpendicular to the axis YY of the chamber itself, while the other slants (with respect to said plane perpendicular to the axis YY) by an angle 'y of between 40 and 50, with a preferred value y
  • the third side of the triangular diametral cross-section of these ring-like grooves is merely ideal and is represented by the fully rectilinear outline of the inner part of the diametral cross-section of the divergent zone 9 supposed without any groove 13.
  • the distance or interval between the first grooves (that is, the distance between the exit edge of one groove and the entrance edge of the next adjacent groove, considered in the direction of flow of the gas stream), immediately downstream the intermediate zone 5, gradually increases among the successive grooves (the first grooves being considered as disposed in a practically continuous sequence, one after the other, with a substantially zero interval).
  • all the grooves have a single diameter, defining their annular dimension, this characteristic determining, in combination with the divergent cone-shape of zone 9, the different depths of the grooves; thus the apexes of the triangular diametral cross-sections (conicident with the maximum depth of the grooves) can be considered as lying in a single cylindrical ideal surface having the diameter D
  • the outline created in the cross-section of the conical and divergent end zone 9 by the presence of the ring-like grooves 13 formed according to the abovedescribed teaching results in greatly increasing the streamline through the interruption-chamber, thereby reducing the occurrence of whirls to a minimum while conveying the decomposition gases in a direction concomitant with that of the deionizing (or quenching) gas.
  • each single elementary flow line has a direction concomitant with the quenching gas flow direction, while, as to the single grooves (whose wall, inclined by the angle y, gives rise to elementary flow lines directed in opposition to the quenching gas) it is the resultant of the single elementary flow lines which acts in the direction concomitant with the quenching gas, inasmuch as there is a vectorial sum between the elementary flow lines coming from the wall inclined by angle 7 and the elementary flow lines coming from the Wall lying in the plane perpendicular to the axis YY of 'the chamber.
  • the phenomenon of the decomposition gas generation from the material constituting the nozzle walls is one of the most important factors which determines the shape of the end zone 9 according to the present invention and, in particular, the number, width and distribution of the ring-like grooves 13 along this zone.
  • the resultant of the elementary flow lines would have directions less favorable to the concomitance and therefore to the interaction with the quenching gas flow; on the contrary, with angles greater than 50, The resultant would have a more favorable direction, but the cross sectional outline of the resulting grooves would be more open, with a less irregular streamline through the interruption chamber, the grooves would be wider and more interspaced (therefore becoming less efficient), and moreover it would be impossible to keep the angle ,8 (which defines the cone-shape of the end zone 9) within the range of values determined to be the most suitable to contribute to the best performance of the nozzle unit.
  • the described improvements not only offer the abovedescribed advantages, but also improve electric arc quenching; the quenching gas flow is allowed to run over and to sw athe the arc nucleus in the most effective and extensive way, because the internal shape of the chamber is such that it greatly facilitates the outflow of quenching gas in way that the gas can follow the electric are very closely throughout the entire opening travel of the contacts (moving contact 3 and fixed contact 20).
  • the intermediate zone 5 having a slightly truncated cone-shape, extends the deionizing action of the quenching gas, thus theintermediate zone 5 and the end zone 9 allow for an increase in the capacity of the interruption throughout the contacts opening travel.
  • the number of ring-like grooves 13 necessary to give excellent performances to the nozzle-unit may range from two to 10, the preferred number of these grooves being between four and six.
  • angle 28 having a value between 14 and 20, the most suitable value having been determined as 17.
  • the type of nozzle described herein isdesigned to be utilized with any type of compressed gas meeting the characteristics imposed by its use in an electric circuitbreaker, and particularly the dielectric requirements.
  • the preferred embodiment of the present invention is most suitable for use with sulphur hexa-fluoride (SP as the arc quenching fluid, whose particularly good quenching characteristics are effectively added to those exhibited by the concerned nozzle.
  • SP sulphur hexa-fluoride
  • a blast nozzle assembly for self-blasting compressed gas electric circuit breakers having axial blast interruption chambers, comprising:
  • a plurality of annular grooves formed in said divergent end zone downstream of said intermediate said tapering angle is approximately 4.
  • said grooves each having: a substantially triangularly shaped diametral cross-section with a vertex angle defined by the meeting of two surfaces of the wall of said end zone, one of said surfaces being substantially perpendicular to said axis of said interruption chamber; and an open base directed toward the outlet end of said interruption chamber, the dimensions of said triangularly shaped cross-sections decreasing from the first groove immediately downstream of said intermediate zone to the last groove furtherest downstream of said intermediate zone and closer to the chamber outlet, the spacing between succeeding grooves increasing in the direction of the chamber outlet.
  • a nozzle assembly according to claim 2 wherein 2O 4.
  • a nozzle assembly according to claim 10 wherein said annular grooves are contained in a portion of said divergent end zone which has an axial length not exceeding two-thirds of the total length of said divergent end zone.

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  • Circuit Breakers (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US00275219A 1971-07-30 1972-07-26 Blast nozzle units with radial holes for self-blasting compressed gas electric circuit-breakers Expired - Lifetime US3816684A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT2698771 1971-07-30

Publications (1)

Publication Number Publication Date
US3816684A true US3816684A (en) 1974-06-11

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ID=11220694

Family Applications (1)

Application Number Title Priority Date Filing Date
US00275219A Expired - Lifetime US3816684A (en) 1971-07-30 1972-07-26 Blast nozzle units with radial holes for self-blasting compressed gas electric circuit-breakers

Country Status (11)

Country Link
US (1) US3816684A (fr)
BE (1) BE786948A (fr)
BR (1) BR7205080D0 (fr)
CA (1) CA973598A (fr)
CH (1) CH546476A (fr)
DE (1) DE2236566A1 (fr)
ES (1) ES405375A1 (fr)
FR (1) FR2148031B1 (fr)
GB (1) GB1400523A (fr)
NO (1) NO134274C (fr)
SE (1) SE372652B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4383152A (en) * 1979-08-15 1983-05-10 Bbc Brown, Boveri & Company, Limited Circuit breaker
US4667072A (en) * 1983-08-24 1987-05-19 Hitachi, Ltd. Gas-insulated circuit breaker
US5155312A (en) * 1990-03-13 1992-10-13 Hitachi, Ltd. Puffer type gas circuit interrupter
US20040256361A1 (en) * 2001-11-14 2004-12-23 Andrzej Nowakowski Power switch
US20120037599A1 (en) * 2009-03-30 2012-02-16 Abb Research Ltd Circuit breaker

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61188825A (ja) * 1985-02-15 1986-08-22 株式会社日立製作所 パツフア式ガス遮断器
CN106841573A (zh) * 2017-04-12 2017-06-13 中铁西北科学研究院有限公司 一种泥石流模拟试验装置及试验方法

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4383152A (en) * 1979-08-15 1983-05-10 Bbc Brown, Boveri & Company, Limited Circuit breaker
US4667072A (en) * 1983-08-24 1987-05-19 Hitachi, Ltd. Gas-insulated circuit breaker
US5155312A (en) * 1990-03-13 1992-10-13 Hitachi, Ltd. Puffer type gas circuit interrupter
US20040256361A1 (en) * 2001-11-14 2004-12-23 Andrzej Nowakowski Power switch
US7022922B2 (en) * 2001-11-14 2006-04-04 Siemens Aktiengesellschaft Power switch with a mobile contact element and extinction gas flow that move in an axial direction when activated
US20120037599A1 (en) * 2009-03-30 2012-02-16 Abb Research Ltd Circuit breaker
US8502101B2 (en) * 2009-03-30 2013-08-06 Abb Research Ltd Circuit breaker

Also Published As

Publication number Publication date
DE2236566A1 (de) 1973-02-08
NO134274C (fr) 1976-09-08
GB1400523A (en) 1975-07-16
NO134274B (fr) 1976-05-31
CA973598A (en) 1975-08-26
BR7205080D0 (pt) 1973-06-28
ES405375A1 (es) 1975-07-16
CH546476A (de) 1974-02-28
BE786948A (fr) 1973-01-29
FR2148031A1 (fr) 1973-03-11
FR2148031B1 (fr) 1977-06-17
SE372652B (fr) 1974-12-23

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