US2067541A - Fusible electric circuit breaking device - Google Patents

Description

Jam. 12, 1937. K. NOBUHARA FUSIBLE ELECTRIC CIRCUIT BREAKING DEVICE Patented Jan. 12, 1937 UNITED :STATES FUSIBLE ELECTRIC CIRCUIT BREAKING Y DEVICE Kantaro Nobuhara; Osaka, Japan Application October 1, 1934, Serial No. 146,432

f In Japan October 10, 1933 2 Claims. (Cl; 200-'120) This invention relates to improvements in a fusible electric circuit-breaking device to be used for high-tension transmission lines. It consists of a plurality of thin flat plates made of a noncombustible and insulating material, each plate having a small hole at its center, a fusible wire threaded through said holes so that the said plates are aligned in contact with each other along their fiat surfaces, and a means to quickly pull out the fusible wire from the holes when the wire is melted at any portion thereof.

The object of this invention is to obtain a fusible electric circuit-breaking device for high-tension lines, wherein the gas produced when the fusible wire is melted diffuses quickly through the radial passages in the shell in order to cool the gas quickly and to ensure only a small cross-sectional area of the gas along an avenue of escape, whereby the interruption of the circuit is performed quickly and without turbulence.

A further object of this invention is to obtain a fusible electric circuit-breaking device for hightension lines, wherein the fusible wire extending through a non-combustible insulating shell having a number of passages for gas therein perpendicular to the passage of the wire is withdrawn from the shell when the wire is melted at any point in the shell.

A further object of this invention is to obtain a fusible electric circuit-breaking device for hightension lines, wherein the fusible wire extending through a non-combustible insulating shell having a number of passages for gas therein perpendicular to the passage of the wire is made of reduced cross-sectional area at one part, so that the wire is always melted at a predetermined point in the shell.

Fig. 1 shows an elevation of a preferred form of the circuit-breaking device according to this invention, illustrating the device at the moment when the wire is melted and the gas is blowing out through the passages adjacent the point of break.

Fig. 2 shows a sectional elevation of a modification, and Fig. 3 is an elevation of another example of this invention.

In Fig. 1, the high-tension line I is supported by insulators 2 in which is inserted a circuitbreaking device. The device consists of a fusible wire 3 extended between terminals 4 fixed on the insulators and a non-combustible insulating shell 5 through which the wire extends. The shell consists of a number of thin plates made of porcelain or like material having a small hole perforated axially through the center of each plate, the plates being aligned in tubular form.

If the fusible wire 3 is melted at any point in the shell 5, the high temperature gas produced by the melting wire is blown out radially through the increased clearances between the plates adjacent to the point of break (compressive stress on said plates being released upon break in the wire), leaving only a small quantity of the gas in the hole for the wire, so that the electro-conducting effect of the gas in the direction of the line is very small. Moreover, since the heat-absorbing capacity of a solid material such as porcelain is surprisingly large as compared to that of air (heat absorbing capacity is proportional to the specific gravity) and since a large cooling surface is provided by the plurality of plates, the heat of the gas passing through the passages is quickly absorbed by the plates so that the gas is cooled rapidly and its electro-conductivity is lowered.

In the modification shown in Fig. 2, a disc 6 having a larger diameter is inserted at intervals of a certain number of small discs I, and the diameter of the fusible wire is reduced at the centre part 8. The terminal parts are made of a material having a good conductivity and are shown as having the shape of a ring 9.

Instead of reducing the diameter of the wire at some point along its length, the wire may be made of different materials having different electro-specific resistances, the material of highest resistance being arranged at the centre part thereof. According to this modification, the wire is always fused and breaks at the centre part.

The discs 6, having a larger diameter, serve to prevent the passage of surface leakage current.

Referring to Fig. 3, the circuit-breaking device is arranged between insulators co-operating with a tensioning device.

The ring 9 provided at each end of the fusible wire of Fig. 2 is hung on a hook ID of a rod H or l2 made of spring metal and shown as fast on an insulator. One or both of the rods is shown as accompanied by a tensioning device. This device serves to tension the fusible wire so that when the wire breaks, it is quickly withdrawn from the shell.

The tensioning device may be of any type. The example shown in Fig. 3 consists of an external case l3 heldon an insulator having a spindle M which tends to turn quickly in the direction shown by an arrow, by means of a strong spring, not shown, provided in the case. A cushion plate I5 is provided on the case, which serves to receive gently the rod H, which latter is shown as mounted on the spindle I, when the rod is turned back quickly by means of the tensioning device. The positions of the rods when the wire has broken are shown in dotted lines.

In case the fusible wire is melted, the rod I2 is quickly withdrawn, withdrawing a part of the wire from the shell, until it rests on the cushion plate. At the moment when the wire is fused, the gas which is produced spreads radially in the gaps between the discs of the shell as beforementioned, and the parts of the broken wire are withdrawn through the shell at high speed, so that an electric arc cannot follow the broken ends of the wire which are being withdrawn.

The device can be arranged in an oil bath as well as in air.

What I claim is 1. A circuit-breaking device for high-tension lines, comprising a fusible wire, and a plurality of thin flat plates separate from each other and made of an incombustible and insulating material, each plate having a small hole at its center, said wire being threaded through said holes, and said plates being aligned in contact with each other along their flat surfaces.

2. A circuit-breaking device for high-tension lines, comprising a fusible wire, and a plurality of thin flat plates separate from each other and made of an incombustible and insulating material, each plate having a small hole at its center, said wire being threaded through said holes, said plates being aligned in contact with each other along their flat surfaces, and additional thin plates, of larger dimensions than said first-mentioned plates, interposed at regular intervals between groups of a predetermined number of said first-mentioned plates.

KANTARO NOBUHARA.

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