Arc-quenching chamber for circuit breakers with a fluid arc-quenching medium, in particular for reduced oil volume or liquified gas circuit breakers

Abstract

 Arc-extinguishing chamber for circuit breakers with fluid arc-extinguishing medium,
constituted by two shaped elements of thermoplastic material, the one of said two elements being coaxially insertable inside the other one, the said one of said two elements being provided in an upper inner portion thereof with a seat for housing stationary electrical contact means, and in correspondence thereof, on its outside surface, with means for distributing along the cylinder the stresses due to the inner pressure generated by the electrical arc, and for the venting to the outside of the gases generated by the electrical arc, it being further­more provided in a lower portion thereof with disc-shaped portions and with a semicylindrical wall, said disc-­shaped portions being suitable to define a first zone of said arc-quenching chamber provided with vent openings, and said wall being suitable to define a second closed zone of said arc-quenching chamber when the said one of the said two elements results operatively inserted inside the other one of the said two elements.

Description

[0001] The present invention relates to an arc-quenching chamber for circuit breakers with fluid arc-quenching medium, in particular for reduced oil volume or for liquified gas circuit breakers.

[0002] Known are arc-quenching chambers realized by the union of a number of flat components (discs), constituted by superimposed layers of bakelized paper, and linked to each other by glueing or by fastening by insulating screws. Such a type of arc-quenching chambers require a complex machining of each individual element of bakelized paper and in general a lengthy and expensive process for their accomplishment.

[0003] Furthermore, known are arc-quenching chambers made from thermoplastic material, which however require, due to constructive reasons, severe geometrical simplifica­tions both in the area of the cavities of the same cham­ber and in the area of the discharges, thus reducing the interruption performances obtainable from the system. In fact, by such a type of chambers, the interruption is accomplished with a less efficient control of the elec­trical arc, thus resulting fatiguing and with decidedly long times.

[0004] Purpose of the present invention is to provide an arc-extinguishing chamber of thermoplastic material which, besides obviating the constructive technological disadvantages as mentioned, allows the necessary "laby­rinth" arrangement of the various portions of the same chamber to be kept unchanged, as if said chamber were accomplished by assembling superimposed discs, further­more allowing the performances which can be obtained by a traditional chamber constituted by superimposed discs to be improved, and at the same time the construction there­of to be made simpler.

[0005] In view of such a purpose according to the present invention, an arc-extinguishing chamber for circuit breakers with fluid arc-extinguishing medium has been accomplished, characterized in that it is constituted by two shaped elements of thermoplastic material, the one of the said two elements being coaxially insertable inside the other one, the said one of said two elements being provided in an upper inner portion thereof with a seat for housing stationary electrical contact means, and in correspondence thereof, on its outer surface, with means for distributing along the cylinder the stresses due to the inner pressure generated by the electrical arc, and for the escape to the outside of the gases generated by the electrical arc, it being furthermore provided in a lower portion thereof with disc-shaped portions and with a semicylindrical wall, said disc-shaped portions being suitable to define a first zone of said arc-quenching chamber provided with vent openings, and said wall being suitable to define a second closed zone of said arc-­quenching chamber when the one of the said two elements results operatively inserted inside the other one of the said two elements.

[0006] The structural and functional characteristics of the present invention shall appear more clearly from the following disclosure, referred to the attached schematic drawings, wherein:

Fig. 1 is an exploded elevation view of the elements constituting the invention;

Fig. 2 is an elevation view of the elements of Fig. 1, in their assembled state;

Fig. 3 is an exploded and partly sectional elevation view, according to arrow F3 of Fig. 1;

Fig. 4 is a sectional view of the elements of Fig. 3, in their assembled state;

Fig. 5 is an elevation view of the upper element according to arrow F5 of Fig. 3;

Fig. 6 is a plan view from the bottom, according to arrow F6 of Fig. 5;

Fig. 7 is a plan view from the top according to arrow F7 of Fig. 5;

Fig. 8 is a section made along path VIII-VIII of Fig. 5;

Fig. 9 is a section made along path IX-IX of Fig. 5;

Fig. 10 is an elevation view of the lower element of Fig. 3;

Fig. 11 is a plan view taken from the bottom accord­ing to arrow F11 of Fig. 10;

Fig. 12 is a plan view from the top according to arrow F12 of Fig. 10;

Fig. 13 is a section made along path XIII-XIII of Fig. 4; and

Fig. 14 is a section made along path XIV-XIV of Fig. 4.

[0007] Referring to the figures, with 10 indicated alto­gether is an arc-quenching chamber, composed by two shaped elements 11 and 12 of thermoplastic material, the element 12 being suitable to be coaxially inserted inside the element 11 by means of guides 13 sliding inside special seats 14 which determine in an univocal way the insertion of elements 11 and 12.

[0008] The element 11, substantially of hollow cylindrical shape, is provided with an outer smooth wall 15 and is divided into two inner zones, a lower zone 16 and an upper zone 17 provided with an opening 40 on the wall 15. The upper zone 17 contributes, together with a lower portion 18 of element 12, to form the true arc-quenching chamber, by means of complementary profiles provided inside the element 11, as well as on said lower portion 18 of element 12.

[0009] Furthermore, an upper portion 19 of element 12 is provided with projections 20 located on its outer sur­face, and suitable to distribute the force generated by the pressure of the arc, so to increase the mechanical strength of the said chamber and at the same time to allow the combustion gases which are formed to be vented to the outside, according to paths generally indicated by arrows 21.

[0010] A variably shaped lower portion 18 of element 12 comprises, besides the guides 13, four discs 23, 24, 25 and 26, positioned parallelly to one another and sepa­rated from the upper portion 19 and from each other by hollow portions 27.

[0011] The discs 23, 24, and 25 are respectively provided with projections 28, 29 and 30 of different sizes, lo­cated in homologous positions on each disc and suitable to engage inside a special guide 32 provided on element 11. In a position opposite to projection 30 of disc 25, provided is a substantially semicylindrical wall 31 ex­tending downward under disc 26. When the element 11 and the element 12 are assembled, the disc 26 and the wall 31 get housed inside a shaped seat 33 provided inside ele­ment 11, so to form a portion of arc-quenching chamber closed by containment walls, whilst the three upper discs 23, 24 and 25 come to lie in correspondence of the open­ing 40 provided on the wall 15, so to form a portion of arc-quenching chamber provided with openings for gas vent to the outside.

[0012] In the normal operation of the arc-quenching chamber according to the present invention, the two elements 11 and 12 shall be united to each other by a suitable resin or bonding agent, and inside the inner cavity 34 of the upper portion 19 of the element 12, a stationary contact (not shown) shall be housed; and inside the zones 16 and 17 of element 11 a movable contact (it too not shown) shall slide.

[0013] In this way, accomplished is an arc-extinguishing chamber, contained inside an unipolar housing filled with an arc-quenching medium, e.g., oil. During the opening of the contacts, the electrical arc generates, by interact­ing with the arc-quenching medium, a pressure controlled by the particular arrangement of the walls and of the cavities, so to promote the interruption of the same arc.

[0014] The particular shapes according to which the thermo­plastic material - used to accomplish the arc-extinguish­ing chamber according to the present invention - is moulded, allow an improved efficacy to be obtained, both relatively to that of the normal arc-quenching chambers realized by means of stacks of discs of bakelized paper, and relatively to the arc-extinguishing chambers realized until today as monolithic pieces, which require extensive geometrical simplifications to be introduced in cavities and walls, due to moulding requirements.

[0015] The present invention has been disclosed to illus­trative and not limitative purposes, and it must be understood that variants and changes can be supplied by those skilled in the art, always within the covering scope of the present invention.

Claims

1. Arc-extinguishing chamber for circuit breakers with fluid arc-extinguishing medium, characterized in that it is constituted by two shaped elements of thermo­plastic material, the one of said two elements being coaxially insertable inside the other one, the said one of said two elements being provided in an upper inner portion thereof with a seat for housing stationary elec­trical contact means, and in correspondence thereof, on its outside surface, with means for distributing along the cylinder the stresses due to the inner pressure generated by the electrical arc, and for the venting to the outside of the gases generated by the electrical arc, it being furthermore provided in a lower portion thereof with disc-shaped portions and with a semicylindrical wall, said disc-shaped portions being suitable to define a first zone of said arc-quenching chamber provided with vent openings, and said wall being suitable to define a second closed zone of said arc-quenching chamber when the said one of the said two elements results operatively inserted inside the other one of the said two elements.

2. Arc-quenching chamber according to claim 1, char­acterized in that the said one of the said two elements is coaxially insertable in an univocal way inside said other one of the said two elements by means of guides provided on the said one of said two elements, sliding inside seats provided on the said other one of the said two elements.

3. Arc-quenching chamber according to claims 1-2, characterized in that said means for the distribution of the operating stresses and for the escape of the gases generated by the electrical arc are constituted by paral­lelepipedal projections provided on the outer upper sur­face of the said one of said two elements.

4. Arc-quenching chamber according to claims 1-3, characterized in that the said other one of said two elements is provided with an opening on its surface in an upper portion thereof.

5. Arc-quenching chamber according to any of preced­ing claims, substantially according to as described and illustrated in the attached figures.

Drawing