JP2508405B2 - How to monitor prefabricated connections - Google Patents

Description

TECHNICAL FIELD The present invention relates to a prefabricated type connecting portion or terminating portion for a rubber / plastic insulated cable (hereinafter referred to as a CV cable).

[Prior Art] A conventional example will be described below with reference to the drawings. Figure 2 shows CV
It is sectional drawing which shows the basic composition of the cable prefabricated type connection part. That is, the ends of the CV cables 1, 1'to be connected are stripped off to expose the cable conductors 2, 2 ', and the connecting pipes 3 are covered for connection. The epoxy insulating cylinder 5 in which the embedded electrode 4 which covers the outer periphery of the connection portion is embedded is formed in a cylindrical shape in which the left and right inner surfaces form a conical tapered surface 5a. Then, the protruding portion 4a of the embedded electrode 4 and the outer circumference of the conductor connecting tube 3 are connected. The rubber mold stress cones 6 and 6'having a conical taper tip are inserted between the insulators 1a and 1a 'of the CV cables 1,1' stripped from both sides of the epoxy insulating cylinder 5. , The conductive layer portions 6a, 6a 'formed of conductive rubber on the left and right rear portions, respectively, to alleviate the electric field. Spring unit attached to the end 8,
It is configured to be pressed so as to be crimped by a constant load by pressing metal fittings 9, 9'of 8 '.

In the CV cable connecting portion or terminal portion thus configured, a cylindrical epoxy insulating tube 5 and rubber mold stress cones 6, 6'are provided around the connecting portion or terminal portion.
A prefabricated method in which the rubber mold stress cones 6 and 6'are pressed by the pressing members 9 and 9'of the spring units 8 and 8'and pressed and compressed against the taper surface 5a of the epoxy insulating cylinder 5 respectively. Mold connection or termination. Since this prefabricated type connection part or termination connection part can significantly reduce the construction time,
Recently, it has also come to be applied to CV cable lines of 154 kV to 275 kV.

In this way, the prefabricated type connection part or terminal part is configured by only incorporating the unitized parts,
It is important to monitor whether the components being constructed are functioning properly and maintaining their function for long periods of time. However, at present, no monitoring system is provided for such a prefabricated type connection or termination.

In particular, the prefabricated connection or termination of the CV cable has an interface between the epoxy insulation tube and the premolded stress cone and cable insulation, and this interface is an important part for electrical insulation. Therefore, it is necessary to monitor whether or not the stress is normally applied to this interface in order to improve the reliability of the prefabricated type connection portion or the termination portion for the CV cable.

[Problems to be Solved by the Invention] As described above, the prefabricated type connection portion or termination portion is
Because pressure is applied to the interface between the epoxy insulation barrel and the pre-molded stress cone and the cable insulation and the pre-molded stress cone, monitoring this will improve the reliability of the connection or termination. Will be connected. However, it was difficult to directly measure the interface stress during operation of the CV cable line. Therefore, there is a need for a method that can monitor that the stress at the interface is in a normal state even when the load of the CV cable changes.

The present invention has been made in view of such points,
An object of the present invention is to provide a method for monitoring the pressure at the pre-mold stress cone interface of a prefabricated type connection portion or termination portion for a CV cable with a pressure sensor or a displacement gauge.

[Means for Solving the Problems] The present invention has a pressure sensor built into a pre-molded stress cone push fitting, a reflector is attached to a spring seat of a spring unit, and a stress cone push plate at a position opposite to this is attached. Pressure is normally applied to the interface between the epoxy insulation tube and the premolded stress cone and between the cable insulation and the premolded stress cone by fixing the optical probe of the optical fiber to and measuring the gap by reflection. Is a way to monitor for.

[Operation] It is possible to constantly monitor whether the insulation state is normal even during operation of the CV cable line, improve the reliability of the connection part or the end part, and prevent accidents before they occur. .

[Examples] Examples of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing the right upper half of the prefabricated type connecting portion. The pressure sensor 10 is embedded in the portion of the pressing member 9'of the spring unit 8'that presses the back surface of the conductive portion 6a 'of the pre-mold stress cone 6'. As the pressure sensor 10, for example, a strain gauge type small pressure sensor such as a model PS-10KB pressure sensor manufactured by Kyowa Denki Co., Ltd. is applied. A plurality of the pressure sensors 10 are attached to the pressing fittings 9'and connected to the data recording device 15 by the lead wires 16 so that the pressure distribution in the circumferential direction of the pre-mold stress cone 6'can be grasped. As a result, for example, when a biased pressing load is applied to the pre-mold stress cone 6'by the spring unit 8'which is a pressing device,
This can be detected from the pressure distribution of the pressure sensor 10 of the push fitting 9 '. Further, the interfacial pressure between the epoxy insulating cylinder 5 and the pre-mold stress cone 6'can be known by knowing the distribution of the pushing load between the pre-mold stress cone 6'and the pressing fitting 9 '.

On the other hand, in the spring unit 8'which is a pressing device,
The reflection plate 11 is attached to one spring seat 9a ', and the optical fiber probe 13 is attached to the opposite position of the other pressing flange 12.
Is arranged so that an optical pulse is emitted from the optical transmitter 14 to the optical fiber lobe 13, and the movable distance of the spring is read by a displacement meter that picks up the reflected light from the reflecting mirror 11. As for the movable distance of the spring, it is possible to clarify how much the pushing load changes and how much the pushing load is, by grasping the moving amount and the pushing load characteristic of the spring unit 8'in advance. be able to.

Further, by detecting the pushing load, the pressure Q at the interface of the epoxy insulating cylinder 5 can be known by the following equation.

Here, P is the pushing load (kg / cm ² ), μ is the Poisson's ratio of the premold stress cone 6, θ is the interface angle of the epoxy insulating cylinder 5.

It is also possible to monitor whether the interfacial pressure obtained from the above equation is not below the minimum pressure required to ensure electrical insulation performance.

The light reflection plate 11 may be attached to the optical probe 13 at a certain angle, and the angle slightly changed depending on the movable distance may be detected and converted into the distance.

As described above, as a monitoring method during operation of the prefabricated type connection section on an actual line, a displacement gauge is installed to continuously monitor the spring length of the spring unit. In the above example, an optical sensor is used, but in addition to this, a resistance sliding wire type potentiometer, a differential transformer type displacement sensor, or an ultrasonic sensor may be inserted for measurement.

[Effects of the Invention] As described above, according to the method for monitoring a prefabricated type connection portion of the present invention, since the pushing load of the premolded stress cone is monitored, the behavior of the connection portion due to a thermal factor is grasped. It becomes possible to do. Further, since continuous monitoring is possible, it becomes an excellent monitoring device.
Further, the sensor is easy to handle, and accurate measurement can be easily performed by the sensor without changing the configuration of the connecting portion.

[Brief description of drawings]

FIG. 1 is a sectional view of a right upper half portion showing a configuration of a prefabricated type connecting portion to which the monitoring method of the present invention is applied, and FIG. 2 is a sectional view showing only an upper half portion showing a basic configuration of the prefabricated type connecting portion. Is. 1,1 '…… CV cable 2 …… Cable conductor 3 …… Conductor connection tube 5 …… Epoxy insulation tube 6,6 ′ …… Pre-molded stress cone 7 …… Protective copper tube 8,8 ′ …… Spring unit 9,9 '... Press fitting, 9a' ... Spring seat 10 ... Pressure sensor, 11 ... Reflector 12 ... Push flange 13 ... Optical fiber probe 14 ... Optical transmitter, 15 ... Data acquisition device

Claims (2)

(57) [Claims] 1. A prefabricated stress cone pressing metal fitting at a prefabricated type connection part or terminal part in which an epoxy insulation cylinder and a premolded stress cone are combined in a CV cable connection part and crimped by a spring unit pressing device. A monitoring method for a prefabricated type connecting part, characterized in that a monitoring system is provided by incorporating a small pressure sensor. 2. A reflection plate attached to the spring pressing device at a prefabricated type connecting part or terminal part in which an epoxy insulating cylinder and a premolded stress cone are combined in a connecting part for a CV cable and pressure-bonded by a pressing device of a spring unit. A monitoring method of a prefabricated type connecting part, characterized in that a monitoring system is provided by disposing a displacement gauge having an optical probe fixed at a position opposite to this.