JPH0590746U - Composite power cable with optical fiber - Google Patents

Abstract

(57) [Abstract] [Purpose] Detecting the initial stage of fire and deterioration by early detecting changes in the transmission form due to deformation and contraction of the sheath due to heat and deterioration of electric wires and cables. [Structure] A power composite cable with optical fibers is configured by helically embedding an optical fiber 6 between an inner sheath 3 and an outer sheath 4 of a power cable 5 provided with a plurality of sheaths. Fire and deterioration of the power cable 5 are detected by the transmission loss of the optical fiber 6. Since the optical fiber 6 does not receive a large external force and exists between the sheaths, it is possible to prevent an increase in transmission loss due to an external force, and it is possible to accurately detect an initial stage such as a fire or deterioration of the power cable 5. it can.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a composite power cable with an optical fiber, and more particularly to a composite power cable with an optical fiber for detecting deformation and contraction of a sheath due to heat and deterioration.

[0002]

[Prior Art]

 In recent years, electric wires and cables have tended to be laid in a multi-row configuration as space saving in various buildings, plants, subways, ships, etc. If a fire should occur in such a situation, there is a risk that the electric wire or cable will serve as a fire propagation path and the fire will spread.

On the other hand, various electric devices including various operation panels such as a power supply panel, which have many halogen-containing polymers such as vinyl wires and high-paron electric wires, are used, and a fire accident should occur. If this happens, the vinyl line will act as a fire propagation path and the fire will easily spread. For this reason, the spread of fire is prevented by the detection means that detects the smoke generated when they burn by a smoke sensor and the measurement means that measures the combustion temperature by a temperature sensor. However, with such a technique, smoke and temperature are detected only when the vinyl wire is completely burned, so it is difficult to detect partial heating, which is the initial stage before full burning. Is.

[0004]

[Problems to be solved by the device]

 In order to solve such a problem of the conventional technology, it is considered to install an optical fiber in an electric wire or a cable to detect a change in transmission form. However, when an optical fiber is installed inside the sheath, the heat is weak in the initial stage before a fire occurs, and deformation or contraction to the inside of the sheath may not occur, so early detection is difficult.

Further, when the optical fiber is provided outside the sheath, the optical fiber itself cannot detect deformation, shrinkage, etc. of the sheath due to heat, and therefore the detection cannot be performed accurately. Furthermore, the optical fiber may be broken, buckled, or peeled due to external damage during installation, making it difficult to maintain the function of the optical fiber. On the other hand, Japanese Patent Publication No. 60-37567 discloses that a communication optical fiber is provided along the longitudinal direction between an outer coating layer and an inner coating layer of a power cable in which a plurality of coating layers are provided on the outer periphery of a cable conductor. The embedded composite power cable with optical fiber is described, and it is conceivable to use the optical fiber of such a composite power cable with optical fiber for fire detection. However, in this composite power cable with optical fiber, the optical fiber is embedded in a straight line in the longitudinal direction between the outer coating layer and the inner coating layer of the power cable. , The elasticity of the optical fiber and the coating layer are different, causing troubles such as breakage, buckling, and peeling of the optical fiber, which leads to deterioration of the function and it becomes impossible to accurately detect deformation, shrinkage, etc. due to heat. .

[0006]

【Purpose】

 The present invention has been made to solve such a conventional problem, and it is possible to detect a fire or a fire by detecting a change in the transmission form due to the deformation or contraction of the sheath due to the heat and deterioration of the wire or cable. It is an object of the present invention to provide a composite power cable with an optical fiber that detects an early stage of deterioration.

[0007]

[Means for Solving the Problems]

 The composite power cable with an optical fiber of the present invention that achieves the above object is a composite power cable with an optical fiber in which an optical fiber is embedded between an inner sheath and an outer sheath of a power cable in which a plurality of sheaths are provided on the outer circumference of a cable conductor. In the cable, an optical fiber is spirally embedded along the longitudinal direction between an inner sheath and an outer sheath.

[0008]

[Action]

 According to the present invention, the optical fiber is spirally embedded along the longitudinal direction between the inner sheath and the outer sheath of the power cable having a plurality of sheaths, so that the optical fiber does not receive a large external force. Since it exists between them, it is possible to prevent an increase in transmission loss due to external force, and it is possible to accurately detect the initial stage of fire and deterioration of the power cable.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a composite power cable with an optical fiber according to the present invention. In this composite power cable 1 with optical fibers, for example, an inner sheath 3 is provided on the outer circumference of a cable conductor 2 by extrusion coating of rubber, plastic, etc., and optical fibers 6 having tensile strength are spirally formed at a predetermined pitch along the longitudinal direction. It's wrapped around. An outer sheath 4 is provided on the outer circumference by extrusion coating of rubber, plastic, or the like.

An appropriate pitch for spirally winding the optical fiber 6 varies depending on the outer diameter (D) of the power cable 5, but is preferably 3D to 50D. This is because if the pitch interval is narrow, the transmission loss becomes large, and the sheath performance deteriorates from the viewpoint of increasing the space factor of the optical fiber with respect to the sheath itself. This is because the elasticity of the optical fiber differs from that of the sheath during the handling of the optical fiber. .

With this structure, the optical fiber 6 exists outside the inner sheath 3 and is separated from the cable conductor 2, so that the optical fiber 6 is less affected by the heat generated by the cable conductor 2 and transmits an optical signal. Can be done stably. Moreover, since the optical fiber 6 exists inside the outer sheath 4, the optical fiber 6 which is weak against external force can be protected from the external force.

Next, the test and the test result of the composite power cable with the optical fiber by the combustion etc. will be described in detail. Example 1 In this test, an optical fiber provided with a pitch of 20D between an inner sheath and an outer sheath of a 600V crosslinked polyethylene insulated vinyl sheath cable (CV cable) having a conductor size of 200 mm ² and a number of wire cores of 3 is used. A composite power cable with fiber was created.

A vertical tray burning test (described in IEEE Std. 383) was conducted on the composite power cable with optical fibers in the center of a test room of 5 m × 5 m × 5 m to detect transmission loss due to the optical fiber. The combustion range of the CV cable was 2.4 m. The length of the optical fiber of the CV cable used in the test was set to 25 m, and an abnormality was detected when the increase in transmission loss was 0.5 dB.

On the other hand, a photoelectric smoke detector was set on the upper part of the test chamber to detect combustion. In the case of the photoelectric smoke detector, it was detected 3 minutes and 20 seconds after the start of the combustion test, but the detection by the optical fiber embedded in the electric power cable was able to detect an abnormality 30 seconds after the start of the combustion test. Example 2 Composite with optical fiber in which an optical fiber was provided between the inner sheath and the outer sheath of a 6600 V cross-linked polyethylene insulation polyethylene sheath cable (CE cable) having a conductor size of 200 mm ² and a number of wire cores of 3 Created a power cable.

Both ends of this composite power cable with optical fiber are cut while leaving the optical fiber and connected to a transmission loss detection device installed only in the observation room in the observation room. Was heated with a heater to carry out the test. After the start of heating, the transmission loss increased when the high-density polyethylene sheath contracted 10 cm from the cross section of the end, and it was possible to detect an abnormality in the transmission form of the optical fiber.

From the above test results, it is clear that by using the composite power cable with optical fiber of the present invention, it is possible to prevent the spread of the fire by the electric wire and the cable serving as a fire propagation path. .. It should be noted that similar results can be obtained by embedding an optical fiber in not only the CV cable and CE cable used in the above test but also other electric wires and cables.

[0017]

[Effect of the device]

 According to the composite power cable with an optical fiber of the present invention, the optical fiber is embedded between the inner sheath and the outer sheath. Abnormality in the transmission form of the optical fiber due to the deformation and contraction of the sheath due to partial heating and deterioration of the electric wire and cable taking the structural form can be detected early and reliably, and serious fires can be reduced. Is possible. Also, since this optical fiber is embedded in a spiral shape along the longitudinal direction between the inner sheath and the outer sheath, the sheath portion contracts (especially the terminal portion) due to heat generation for some reason in the power cable. In some cases, the electric equipment connected to the power cable may be destroyed, but it can be detected in advance.

[Brief description of drawings]

FIG. 1 is a perspective view of a composite power cable with an optical fiber according to an embodiment of the present invention.

[Explanation of symbols]

 1 ... Composite power cable with optical fiber 2 ... Cable conductor 3 ... Inner sheath 4 ... Outer sheath 5 ... Power cable 6 ... Optical fiber

Claims (1)

[Scope of utility model registration request] 1. A composite power cable with an optical fiber in which an optical fiber is embedded between an inner sheath and an outer sheath of a power cable in which a plurality of sheaths are provided on the outer periphery of a cable conductor, wherein the inner sheath and the outer sheath are provided. A composite power cable with an optical fiber, characterized in that the optical fiber is embedded spirally along the longitudinal direction between the two.