US3001050A - Arc interrupting device - Google Patents

Description

Sept. 19, 1961 D. w. COLLIER 3,001,050

ARC INTERRUPTING DEVICE Filed July 2, 1959 INVENTOR. Donald ZM CaZZa'er' BY/wd,

Patented Sept. 19, 1961 3,001,050 Anc INTERRUPTING DEVICE Donald W. Collier, Wayne, NJ., assignor to McGraw- This invention relates to circuit .interrupting devices and more particularly to an arc extinguishing medium for a circuit interrupting device.

Upon the opening of a faulted circuit by certain types of overcurrent protective devices, an arc may be struck at the break so that the fault current is not interrupted until the arc is extinguished. This arc current is generally carried by electrons emitted from the parted conductors and positive ions formed as the result of collisions between these emitted electrons and gas molecules in the arc path and also by thermal ionization due to the heat of the arc itself. The positive ions play an important role in maintaining the arc since it is their collisions with the negative side of the break that maintains its temperature and emission of electrons. -In the case of a fuse, this ionization is greatly enhanced by the metallic vapor formed between the parted ends of the fusible element as the fuse blows. In some electrical systems it is imperative that this arc be rapidly extinguished so that the duration of the fault current is insuicient to result in damage to the systems components.

It is the object of this invention to provide circuit iny terrupting device with an arc quenching medium which Vgaseous arc quenching medium for fuses which accomplishes arc extinction by capturing emitted electrons and by combining chemically with the metalized vapor and ends of the parted fusible element to severely limit ionization.

Other objects and advantages of the invention will become apparent from the following detailed description of the invention taken in view of the accompanying drawing which shows a fuse having a gaseous arc extinguishing medium according to the invention.

In general terms, the invention comprises providing a fuse with a gaseous arc extinguishing medium 'containing perchloryl uoride, chemically symbolized C1031?. This gas accomplishes arc extinction in two ways. First, it has a high electron aiiinity enabling it to capture electrons emitted from the parted ends of the fusible element, thereby preventing these electrons from colliding with gas molecules in the arc path to form positive ions necessary to sustain the arc current. Second, when subject to the heat of the arc, C1031: decomposes into an oxidizing agent which oxidizes the metallic vapor formed as the fuse blows, and also oxidizes the ends of the parted element. The oxides thus formed are non-conductive so that a non-conducting medium is interposed in the arc path to severely reduce its current carrying ability. In addition, any oxide formed in the break will increase the electrical resistance of the fusible element and thereby promote arc extinction.

Referring now to the drawing in greater detail, the circuit interrupting device shown therein, comprises a fuse 10 having a hollow casing 12 of any suitable gas impervious insulating material, such as glass or the like, and a pair of conductive end caps 14 and 16, disposed at each end of'casing 12 and secured thereto in a hermetically sealed relationship by a suitable cementing compound 18. Casing' 12 and end caps '14 and 16 deiine a hermetically sealed chamber 19. A fusible element 20 is disposed coaxially within the housing and is electrically connected to each of the conductive end caps .14 and 16 to complete the electrical circuit through the fuse. A nipple 22 is provided in casing I12 so that chamber 19 may charged with ClO3F.

In operation, when the fusible element 20 is subjected to a fault current, it will begin to melt at some point along its length and then separate as the heated metal vaporizes. If the circuit voltage is suciently high, an arc will be struck at the break. As the arc lengthens, due to evaporation of the material from the ends of the fusible element 20 a portion of the molecules of ClOF decompose to form a strong oxidizing agent which combines with the metallic vapor and the ends of the fusible element to form non-conducting metallic oxides. In addition, the ClOaF molecules and any gases formed by this decomposition capture emitted electrons, thus substantially limiting the free electrons available to form the positive ions necessary to sustain the arc. As a result of these actions, the arc will be extinguished.

I claim:

1. A circuit interrupting device having a container, a fusible element disposed within said container and adapted to be-connected in an electrical circuit, and a gaseous arc extinguishing medium disposed within said container and including perchloryl fluoride.

2. A circuit interrupting device having a container, an arc extinguishing medium disposed within said container and including perchloryl fluoride, and separable electrical conductive means disposed within said container for interrupting an electrical circuit whereby an arc will be struck between the separated portions thereof, said medium electing extinction of said arc.

3. A circuit interrupting device having a container, a gaseous arc extinguishing medium disposed within said container and including perchloryl iiuoride, and means for striking an arc within said container, said medium effecting extinction of said arc.

References Cited in the tile of this patent UNITED STATES PATENTS 2,221,720 Prince Nov. 12, 1940 2,539,261 Miller Jan. 23, 1951 FOREIGN PATENTS 303,090 Great Britain Dec. 28, 1928

Claims (1)

1. A CIRCUIT INTERRUPTING DEVICE HAVING A CONTAINER, A FUSIBLE ELEMENT DISPOSED WITHIN SAID CONTAINER AND ADAPTED TO BE CONNECTED IN AN ELECTRICAL CIRCUIT, AND A GASEOUS ARC EXTINGUISHING MEDIUM DISPOSED WITHIN SAID CONTAINER AND INCLUDING PERCHLORYL FLUORIDE.

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