JPH09259652A - Overcurrent sensing cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect generation of an overcurrent by applying a PTC composition placed in a high resistance condition, when it exceeds a preset temperature, to the periphery of an insulation coating layer. SOLUTION: In an overcurrent sensing cable A, outside a wire 1 in a core part, a synthetic resin insulation coating layer 2 is formed in the lengthwise direction, and in this outside, a PTC composition layer 3 is interrupted in the lengthwise direction, and the cable is formed. Further, outside the PTC composition layer 3 is coated with an electric insulation peripheral coating layer 4. To the PTC composition layer 3, two detecting wires 5, 5' are connected and drawn out to the outside. Here, the PTC composition layer 3 is a conductive resin composition, a low resistance value is displayed at an ordinary temperature, and the composition, when it exceeds a certain temperature, is transferred to a high resistance condition. The PTC composition 3 is made by successively mixing a conductive filler in a crystalline cross-linked polymer, to be applied to the periphery of the insulation coating layer 2. Consequently, an overcurrent is generated in the case of carrying a current in the wire, when the temperature rises by generated heat, a temperature of PTC composition exceeds a preset value, the current is sensed through the detecting wire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable in which an insulating coating layer is formed on an electric wire when an overcurrent occurs in the electric wire in the cable, or when the electric wire has a high temperature exceeding a design value. The present invention relates to an overcurrent detection cable capable of sensing.

[0002]

2. Description of the Related Art Generally, a metal fuse, an electric switch type breaker, or a PTC element is provided to protect an electric device and a circuit conductor when an abnormality occurs in a circuit connecting the electric device and an overcurrent flows. The circuit is cut off via a protection device using the above. PTC
The element is an element in which a resin composition having a positive temperature resistance coefficient is sandwiched between electrodes. For example, in JP-A-64-2303, a PT having a PTC characteristic as shown in FIG.
Circuit protection element E in which layer C is provided between two electrodes b and b '
Is disclosed.

However, all of these devices are installed at the end of the electric wire which is a circuit conductor or in the middle of the electric wire leading to the equipment, and when the current value set according to the allowable current of the electric equipment is exceeded. It is designed to work. Therefore, it is not designed to cut off the circuit by sensing heat generation due to current exceeding the permissible current of the wire itself, so-called overcurrent, or high temperature condition exceeding the design value. Since the detection is impossible, there is a problem that the protection device may not operate and a failure may occur when an abnormality occurs in the electric wire itself.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is possible to detect heat generation due to an overcurrent of the electric wire itself or an overcurrent that can detect a high temperature state due to an abnormal environment. It is an object to provide a sensing cable.

[0005]

In order to achieve the above object, the overcurrent sensing cable of the present invention is a PTC composition comprising a conductive resin composition having PTC characteristics on the outside of an insulating coating layer covering an electric wire. It is characterized in that a layer is provided.

The PTC composition forming the PTC composition layer is preferably a PTC composition formed by kneading a conductive filler in a crystalline crosslinked polymer (claim 2). As the cross-linked polymer, polyethylene, polypropylene, polyvinylidene fluoride, a copolymer of vinylidene fluoride and trifluoroethylene, a copolymer of vinylidene fluoride and tetrafluoroethylene, polyamide, polycarbonate, polyvinylidene chloride, polyethylene oxide,
Polyvinylcarbazole or the like is used. The conductive filler is not particularly limited as long as it has conductivity such as carbon-based, silver-based, nickel-based, etc.
The powder is preferably about 100 μm.

It is effective that the PTC composition layer is arranged at a plurality of positions in the longitudinal direction of the electric wire (claim 3). P
It is preferable to connect an electric wire for detection to the TC composition layer (claim 4). It is preferable to form an outer peripheral coating layer on the outside of the PTC composition layer (claim 5).

[0008]

Embodiments of the present invention will be described below. FIG. 1 is a perspective view showing an overcurrent detection cable A according to an embodiment of the present invention. Overcurrent detection cable A
The insulating coating layer 2 made of a synthetic resin material is formed in the longitudinal direction on the outer side of the electric wire 1 of the core part, and the PTC composition layer 3 is intermittently formed on the outer side of the insulating coating layer 2 in the longitudinal direction. There is. The outer surface of the PTC composition layer 3 is entirely covered with an electrically insulating outer peripheral coating layer 4. In the PTC composition layer 3,
Two electric wires for detection 5, 5'are connected and led out to the outside.

The electric wire 1 is an electric wire which constitutes a core portion of a general covered electric wire, and as the insulating covering layer 2, polyvinyl chloride,
It is covered with an electrical insulating material such as polyethylene, polyurethane, or Teflon.

The PTC composition layer 3 is a conductive resin composition having PTC characteristics, that is, it has a relatively low resistance value at room temperature and a positive temperature resistance coefficient that shifts to a high resistance state at a certain temperature. It is composed of the conductive resin composition. The PTC composition layer 3 is formed by applying a composition prepared by kneading a conductive cross-linking polymer into a crystalline cross-linked polymer around the insulating coating layer 2.

As the cross-linked polymer, polyethylene, polypropylene, polyvinylidene fluoride, a copolymer of vinylidene fluoride and trifluoroethylene, a copolymer of vinylidene fluoride and tetrafluoroethylene, polyamide, polycarbonate, polyvinylidene chloride, polyethylene oxide. , Polyvinylcarbazole, and the like.

As the cross-linking method, a physical method by irradiation with radiation such as an electron beam or a chemical method using various peroxides or silane coupling agents can be applied. The conductive filler is not particularly limited as long as it has conductivity such as carbon-based, silver-based, nickel-based, etc.,
It is preferable that the powder has a particle size of about 1 to 100 μm.

On the surface of the PTC composition layer 3, detection electric wires 5 and 5'made of coated electric wires are connected at positions substantially symmetrical with respect to the central axis of the electric wire 1. Perimeter coating layer 4
Is coated with an electrical insulating material such as polyvinyl chloride, polyethylene, polyurethane, or Teflon, as in the case of the insulating coating layer 2.

As shown in FIG. 2, the overcurrent detection cable A is provided with a circuit in which a battery 6 as a power source is connected to one detection electric wire 5 and an ammeter 7 is connected to the other detection electric wire 5 '. Thereby, the change in the resistance value of the PTC composition layer 3 can be detected. Therefore, when the temperature of the PTC composition layer 3 exceeds a certain set value due to heat generated by generating an overcurrent when the electric wire 1 is energized or a temperature rise due to a change in environment, the electric wire for detection 5, It is possible to turn on a warning lamp or cut off the electric current of the electric wire 1 by forming a circuit or the like for operating a relay based on a signal obtained through 5 '.

If the PTC composition layer 3 is intermittently formed in a ring shape at a plurality of positions in the longitudinal direction of the electric wire 1 and the detection electric wire is led out from the PTC composition layer 3 at each position, It is possible to detect an abnormal temperature rise at the position.

[0016]

According to the present invention, since the PTC composition layer is provided on the outside of the insulating coating of the electric wire, the heat generated by the overcurrent generated in the electric wire inside the PTC composition layer is immediately generated by the PT.
The PTC composition layer can be transferred to the high resistance region by conducting to the C composition layer. Therefore, it is possible to detect an overcurrent of the electric wire itself and also to detect a temperature rise due to a change in environment. Further, by providing the PTC composition layer intermittently at a plurality of positions in the longitudinal direction of the electric wire, it is possible to detect the position where the abnormal temperature rise occurs, and it is possible to identify the position where the short circuit occurs. is there.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating an overcurrent detection cable according to an exemplary embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a circuit for detecting a change in resistance value of a PTC composition layer of the overcurrent detection cable of FIG.

FIG. 3 is a cross-sectional view showing a conventional circuit protection element.

[Explanation of symbols]

 A Overcurrent detection cable 1 Electric wire 2 Insulation coating layer 3 PTC composition layer 4 Perimeter coating layer 5, 5'Detection electric wire

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H01B 1/20 H01B 1/20 Z H01C 7/02 H01C 7/02

Claims (5)

[Claims] 1. A PT is provided on the outside of an insulating coating layer covering an electric wire.
An overcurrent detection cable comprising a PTC composition layer comprising a conductive resin composition having C characteristics. 2. The overcurrent sensing according to claim 1, wherein the PTC composition forming the PTC composition layer is a PTC composition formed by kneading a conductive filler in a crystalline crosslinked polymer. cable. 3. The overcurrent detection cable according to claim 1, wherein the PTC composition layer is arranged at a plurality of positions in the longitudinal direction of the electric wire. 4. The overcurrent detection cable according to claim 1, wherein a detection electric wire is connected to the PTC composition layer. 5. The outer peripheral coating layer is formed on the outer side of the PTC composition layer, wherein the outer peripheral coating layer is formed.
Alternatively, the overcurrent detection cable according to claim 4.