JP2573762Y2 - Current limiting resistance wire - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current limiting resistance wire, and more particularly, to a current limiting resistance wire having a glass fiber coating layer on the outer periphery of a conductor having current limiting characteristics.

[0002]

2. Description of the Related Art Generally, a power supply is connected between a power supply and a load,
The current limiting resistance wire used for the electrical equipment control center equipped with a circuit breaker that interrupts the circuit current has the function of generating heat by a large current such as a short circuit and effectively limiting the large current by Joule heat. ing. Conventionally, as such a current-limiting resistance wire, an insulating layer of asbestos fiber braid is provided on a conductor having current-limiting characteristics, and an insulating layer of polytetrafluoroethylene or silicone rubber having excellent heat resistance is provided thereon. Wires with different configurations are used.

[0003]

However, such a conventional current-limiting resistance line has a drawback that the working environment is polluted because asbestos fibers harmful to the human body are used. Since the fiber is recognized as a harmful specific chemical substance and its use is restricted, it is difficult to manufacture a current-limiting resistance wire having such a configuration. On the other hand, as a material having good heat resistance in place of asbestos fiber, general glass fiber and soda glass fiber are known, and these glass fibers have a heat resistance temperature of 600 ° C.
When these glass fibers are coated directly on a conductor having current-limiting characteristics, the temperature of the conductor during use reaches 800 ° C. to 900 ° C. in a short time because the temperature is about 200 ° C. to 200 ° C. In addition, the coating with soda glass fiber has a disadvantage that the heat resistance is poor and the quality is reduced. Quartz glass fiber is known as a fiber having a heat-resistant temperature of about 1000 ° C. However, such quartz glass fiber is expensive, and if it is thickly coated just above a conductor having a current-limiting characteristic as a heat insulating layer, the manufacturing cost of the entire electric wire is reduced. There was a drawback that it became expensive. Therefore, an object of the present invention is to provide a current-limiting resistance wire which does not use asbestos fibers which are harmful to the human body, has good heat resistance, and can reduce the manufacturing cost.

[0004]

The current-limiting resistance of the present invention is as follows.
A primary glass fiber coating layer made of quartz glass fiber is provided on the outer periphery of a conductor having current-limiting characteristics, and the outer periphery of the primary glass fiber coating layer has a thickness greater than that of the primary glass fiber coating layer. A secondary glass fiber coating layer made of general glass fiber and an insulating layer made of silicone rubber are sequentially provided.

[0005]

According to the current limiting resistance wire of the present invention, the secondary glass fiber coating layer is protected by forming the primary glass fiber coating layer having a high heat-resistant temperature to be thin, and the heat-resistant temperature is low and the manufacturing is performed. By forming the low-cost secondary glass fiber coating layer thicker, the thermal resistance of the secondary glass fiber coating layer is increased, and as a result, the heat insulation layer composed of the primary and secondary glass fiber coating layers is increased. The temperature of the outer surface is reduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. In FIG. 1, reference numeral 1 denotes a conductor having current-limiting characteristics formed by twisting current-limiting strands made of iron, a cobalt alloy, or the like. And a function to limit a large current. A braid 2 made of quartz glass having a heat-resistant temperature of about 800 ° C. to 1000 ° C. is provided as a primary glass fiber coating layer having a high heat-resistant temperature on the outer circumference of the conductor 1 having the current-limiting characteristics. The thickness of the braid 2 made of quartz glass is about 150 μm, and this thickness is sufficiently ensured by, for example, a single braid of 850th quartz glass fiber. On the first glass fiber coating layer, as a second glass fiber coating layer, the heat resistance temperature is 4
A braid 3 made of general glass at about 00 ° C. to 600 ° C. is provided. The thickness of the braid 3 made of general glass is 700μ
m, and this thickness is sufficiently ensured by, for example, a double braid of 390th ordinary glass fiber. On the secondary glass fiber coating layer, an extruded coating layer 4 of silicone rubber is provided as an insulating layer with a thickness of about 1.0 mm to 1.5 mm.

[0007] In the current limiting resistance wire having such a configuration, the temperature of the conductor 1 having current limiting characteristics at the time of short circuit or the like is 800 ° C.
Even when the temperature reaches about 900 ° C., the second glass fiber coating layer having a low heat-resistant temperature is protected by the first glass fiber coating layer having a high heat-resistant temperature, and the second glass fiber coating layer having a low manufacturing cost is thickened. By forming, the temperature of the outer surface of the heat insulating layer composed of the primary and secondary glass fiber coating layers can be significantly reduced. On the other hand, even if the thickness of the primary glass fiber coating layer provided on the outer periphery of the conductor 1 having the current limiting characteristic can be made small, the secondary glass fiber coating layer can be sufficiently protected, so that the entire glass fiber coating layer As a result, it is possible to provide a current-limiting resistance wire whose manufacturing cost is not so high and the whole electric wire is inexpensive. In the current limiting resistance wire of the above embodiment, a braid made of general glass fiber is used as the secondary glass fiber coating layer, but the present invention is not limited to this, and a braid made of soda glass fiber may be used. Instead of the extruded insulating layer 4 made of silicone rubber, an insulating layer made of an insulating material having good heat resistance such as polytetrafluoroethylene ethylene may be extruded.

[0008]

In the current-limiting resistance wire of the present invention, the secondary glass fiber coating layer having a low heat-resistant temperature is protected by the primary glass fiber coating layer having a high heat-resistant temperature, and the temperature of the outer surface of the heat insulating layer is reduced. Is greatly reduced by an increase in the thermal resistance of the secondary glass fiber coating layer formed thick. Also, even if the thickness of the primary glass fiber coating layer provided on the outer periphery of the conductor is formed to be thin, the secondary glass fiber coating layer can be sufficiently protected, so that the manufacturing cost of the heat insulating layer as a whole is very high. And a relatively inexpensive current limiting resistance wire can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a current limiting resistance wire of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Conductor which has a current-limiting characteristic 2 ... Braid with quartz glass 3 ... Braid with general glass 4 ... Extruded insulating layer

Claims (1)

(57) [Scope of request for utility model registration] 1. A quartz glass directly around a conductor having current-limiting characteristics.
First glass fiber coating layer made of cellulose fiber is provided, the secondary glass fiber coating layer made of ordinary glass fibers thicker than primary glass fiber coating on the outer periphery of the primary glass fiber coating And a silicon rubber insulating layer are sequentially provided.