US1959770A

US1959770A - Circuit interrupter

Info

Publication number: US1959770A
Application number: US570132A
Authority: US
Inventors: Slepian Joseph
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1931-10-21
Filing date: 1931-10-21
Publication date: 1934-05-22
Anticipated expiration: 1951-05-22

Description

May 22, 1934. J. SLEPIAN CIRCUIT INTERRUPTER Filed Oct. 21. 1931 l N V E N TO R .jse oh 5/ 0/1470.

WITNESSES:

'ATT6RN Y 42 Ma K Patented May 22, 1934 CIRCUIT INTERBUPTER Joseph Slepian, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application October 21, 1931, Serlal No. 570,132

' 18 Claims. (01.200-120) My invention relates to circuit interrupters and more particularly to a fuse for interrupting high voltage circuits. In the circuit interrupter of my invention, the arc is extinguished by the 9 generation of gas, due to the decomposition of material along the arc stream to cause turbulence, resulting in volumes of fresh un-ionized gas being in-mixed with the hot are gases to deionize them.

An object of my invention is to provide members of a solid material along the arc path which, when acted upon by the arc, give off a. large volume of a condensable gas. These members of gas generating material are positioned at spaced intervals, and means for condensing the gas are provided in these spaces. This makes possible the construction of a high voltage fuse wherein great length is not necessary in order to give sufiicient insulation between the terminal members, since the provision of condensers at spaced intervals between the gas generating material relieves the pressure within the circuit interrupter and makes it unnecessary to leave an opening therethrough of such size as to allow the escape of gas as in an expulsion fuse. This arrangement of alternate condensers and gas generating means also makes it possible to use a smaller opening through the walls of gas generating material, since it is not necessary to provide openings of such size as would be necessary to permit a flow of all of the gas through the openings out the end of the tube. This allows the gas generating material to be positioned closer to the are where it will be more readily decomposed and where it will be more efiective in extinguishing the arc.

Another object of my invention is to provide insulating spacers between the sections of the gas generating material so as to allow the use of a. material which is desirable from the standpoint of amount of gas generated, but which may not retain its insulating properties at high temperatures. This construction maintains the total dielectric strength along the arc path at a high value even though the molten surface of the gas generating material may be somewhat conducting.

A further object of my invention is to provide a fuse which is entirely enclosed and self-contained and out of which there is no blast of hot ionized gases which may come in contact with adjacent apparatus, thus making the interruption of the circuit quiet and safe.

These and other objects and advantages 01' my invention will be more fully apparent from the following description and the drawing, in which Figure 1 is a view, partially in side elevation and partially in longitudinal cross section, of a fuse embodying my invention, and

Fig. 2 is a sectional view taken transversely through the fuse on the line II-II of Figure 1.

In the embodiment of my invention illustrated on the drawing, a tubular casing 5 of fiber or other suitable insulating material having good mechanical strength is provided. The ends of the tubular casing 5 are closed by metal cap members '7 secured to the tube 5 by any suitable means such as a screw thread. Within the tubular casing 5 are positioned a plurality of members 9 of a material which, when acted upon by the arc, evolve a gas which may be readily condensed. Each of the members 9 of gas generating material is in the form of a solid disk which fits within the fiber tube 5 and is provided with an opening 11 through the center thereof. The disks 9 of gas generating material are provided at spaced intervals along the whole length of the tubular casing and are spaced apart by condensers in the form of a plurality of annular metal rings 13 which are spaced apart by annular rings of insulating material 15. A fusible element 17 extends through the aligned openings in the disks of gas generating material 9 and the annular metal rings 15 and is electrically connected to each of the metal cap members 7 as by solder 19.

The disks 9 of gas generating material may be of any desirable material which has the property of giving oil a condensable gas when acted upon by the arc. It has been found that materials such as boric acid, gypsum and ammonium alum may be used for this purpose.

One of the most desirable materials is boric acid, since it may be readily compressed by the application of pressure into solid cakes which have such mechanical strength that they may be used without difficulty. When boric acid (H'aBOa) is acted upon by the are, it is decomposed, giving off water vapor (H2O) and leaving boric oxide (B203) The 1 0 water vapor given off is effective in causing turbulence to in-mix volumes of fresh un-ionized gas with the arc to deionize it, and, since the water vapor is non-inflammable, there is no danger of an explosion which might rupture the casing of the fuse. The water vapor after passing through the arc comes in contact with the metal plates 13 positioned between the disks 9, and since the metal plates 13 are at a relatively low temperature, the water vapor is condensed, thus relieving the gas pressure within the container. The use of boric acid is also desirable, since it is an extremely good insulator and retains its insulating properties even when it has been heated to a high temperature and is in. a molten state. Another advantage of boric acid is that it is non-hygroscopic, thus repelling water so that it does not lose its insulating properties if placed in a humid atmosphere.

For some applications it has been found that the material for supplying the deionizing gas may be gypsum (CaSO42HzO), which is a calcium sulphate having water combined therewith. This material is decomposed by the arc giving off water vapor (H2O), sulphur dioxide (S02) and oxygen (02) leaving solid calcium oxide (CaO). While gypsum does not give results anywhere near as good as boric acid, it may be used in circuit interrupters where very high interrupting capacities are not necessary.

A material which is particularly adapted for use in the structure of this application is ammonium alum (Al2(NH4)2(SO4) 424H2O). This is decomposed by the are giving off water vapor (H2O), sulphur dioxide (S02), ammonia (NH3) and leaving the solid aluminum oxide (A1203). Ammonium alum is superior to boric acid from the standpoint of volume of gas evolved, but it does not maintain its insulating properties at the high temperatures to which it is subjected by the arc. While ammonium alum is a good insulator when cold, it melts at 89 C. and becomes a good conductor. It loses water rapidly at 150 C. so that this may be taken for the temperature of rapid decomposition. This means that the surface left immediately after the arc extinguishing will be an electrically conducting film of the molten saltv which will break down under voltage and restart the arc unless other insulation is provided along the arc path. The use of ammonium alum is made possible with the structure of this invention, since the members 9 when of ammonium alum are spaced from each other by the metal rings 13 and the insulating rings 15 so that there is no continuous surface of ammonium alum extending along the arc path from one terminal of the fuse to the other.

From the above description of the specific modification of my invention illustrated on the drawing, it is apparent that I have provided a fuse which is extremely efiective for interrupting high voltage circuits and which overcomes the objections which have been present in expulsionfuses now used for this service. While my invention has been illustrated as being applied to a fuse, it should be understood that the structure may be readily modified so as to be used in a circuit breaker without departing from the spirit of my invention. Other changes and modifications may be made without departing from my invention as defined in the following claims.

I claim as my invention:

1. Inan arc extinguishing device, means positioned along the arc path at spaced intervals for supplying a gas, a substantial part of which is readily condensable, for extinguishing the arc, and means between said spaced gas supplying means for condensing said gas.

2. In an arc extinguishing device, means along the arc path including a plurality of members of a material which gives off a gas, a substantial part of which is non-inflammable and readily condensable, when acted upon by the arc, said members having spaces therebetween, and means occupying a part of said spaces for condensing the gas given off by said material.

3. In an arc extinguishing device, means along the arc path including a plurality of members of a material which is a solid at ordinary tempera tures and which gives off a gas, a substantial part ofwhich is readily condensable, when acted upon by the are, said members having spaces therebetween,v and a plurality of metallic members in said spaces for condensing the gas given oil by said material.

4. In an arc extinguishing device, means of solid material positioned along the arc path, at spaced intervals, for evolving water vapor, under influence of the arc, and condensing means positioned between said spaced, vapor supplying means.

5. In an arc extinguishing device, means defining an opening in which the arc plays, said. means including members which generate a gas, a substantial part of which is readily condensable, when exposed to the arc, and metallic members positioned between some of said gas generating members for condensing said gas.

6. In an arc extinguishing device, a chamber surrounding the arc path and closed on its sides,

openings therethrough forming a chamber for the arc, and a plurality of sheets of metal between each' of said disks for condensing said gas.

8. In an arc extinguishing device, members of boric acid positioned along the arc path for giving ofi water vapor under action of the arc, and condensing means positioned between said members of boric acid for condensing said water vapor.

9. In a circuit interrupter, a closed chamber having a pair of external electrical terminal members, and means within said chamber and electrically connected to said terminal members .for causing an arc, a portion of the walls of said chamber comprising solid members positioned at spaced intervals along the path of said are 10. In a circuit interrupter, a tubular insulating casing, electrical terminal members closing the ends of said casing, aplurality of disks of a solid material positioned within said casing at spaced intervals and of a material which gives off a non-inflammable, condensable gas when acted upon by the arc, said disks having openings therethrough, a plurality of annular metal rings positioned between said disks, and a fusible element electrically connected to said terminal members and extending through the openings in said disks and said annular rings.

11. In an arc extinguishing device, solid members positioned along the arc path which when acted upon by the arc evolve a gas for extinguishing the arc, and insulating means having a greater dielectric strength when subjected to the action of the arc than said gas evolving means interposed among said gas evolving means for improving the overall insulating qualities thereof.

12. In an arc extinguishing device, a plurality of solid members along the arc path, said members being of a material which gives ot! a gas for extinguishing the arc, and means of a material having a greater dielectric strength when subjected to the action of the arc than said gas evolving material for insulating the surfaces of said solid members adjacent the are from each other and thereby maintaining high resistance across the surfaces of said members along the arc path.

13. In an arc extinguishing device, means along the arc path which when acted upon by the arc evolves a gas for extinguishing the arc, and insulating inserts, of a material having a greater dielectric strength when subjected to the action of the arc than said gas evolving material, positioned in the surface of said gas evolving means along the arc path for maintaining the dielectric strength along said surface when it is at a high temperature due to the arc.

14. In an arc extinguishing device, a chamber in which the arc plays, said chamber having walls along the arc path including alternate members of insulating material and members which give off an arc extinguishing gas when acted upon by the arc, the dielectric strength of said members of insulating material being greater than the dielectric strength of said gas producing members when both are subjected to the action of the arc.

15. In an arc extinguishing device, means along the are path of ammonium alum for giving oil a gas for extinguishing the arc, and insulating gaps in the surface of the ammonium alum for maintaining high dielectric strength along said surface when acted upon by the arc.

16. In an arc extinguishing device, a material along the arc path which evolves a gas, a substantial part of which is readily condensable, when subjected to the influence of the are, metallic means for condensing said gas positioned at spaced intervals along the arc path, and insulating gaps in the gas evolving material having a greater dielectric strength when subjected to the action of the arc than said gas evolving material for maintaining the dielectric strength along the arc path during the circuit interrupting operation.

17. In an arc extinguishing device, a plurality of disks of a solid material which gives oiT a gas, a substantial part of which is readily condensable. when acted upon by an arc, said disks having openings therethrough forming a chamber for the arc, a plurality of sheets of metal between said discs for condensing said gas, and insulating means between said discs for maintaining the dielectric strength along the arc path at a high value.

18. In a circuit interrupter, a tubular insulating casing, electrical terminal members closing the ends of said casing, a plurality of disks of a solid material positioned within said casing at spaced intervals and of a material which gives ofi a gas, substantially all of which is non-inflammable and readily condensable, when acted upon by the are, said disks having openings therethrough, a plurality of annular metal rings positioned between said disks, and a plurality of annular rings of insulating material positioned between said annular metal rings.

JOSEPH SLEPIAN.

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