JP2674265B2 - Partial discharge detection method for prefabricated type connection part for CV cable - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a partial discharge detection method for a prefabricated type connection portion for a CV cable.

[Prior Art] 154kv ~ 275kv CV cable connection part, tape mold type connection part using polyethylene tape containing a cross-linking agent,
Alternatively, an extrusion-molded connecting portion in which molten polyethylene is formed by extrusion using an extrusion device has been put into practical use. The latter extruded mold type connection part has excellent electrical insulation performance because it is integrated with the cable insulator by heat molding, but there is a problem that it is difficult to apply when assembling the connection part in a limited time. . Therefore, an epoxy unit made of epoxy resin, a rubber mold stress cone made of ethylene propylene rubber or silicon rubber, and parts such as a spring unit for applying a load to the epoxy unit are assembled into a unit in advance, and a prefabricated type connecting portion configured by them is formed. Is being developed. As shown in Fig. 2, this prefabricated type connecting part is a cable conductor in which the ends of the CV cables 1, 1'to be connected are first stripped off.
2, 2'is exposed and the connecting pipe 3 is covered to connect. The epoxy insulating cylinder 5 in which the embedded electrode 4 to be covered on the outer periphery of the connection portion is embedded is molded in a cylindrical shape in which the left and right inner surfaces are formed with conical tapered surfaces 5a. And
The projection 4a of the embedded electrode 4 and the outer circumference of the conductor connecting tube 3 are connected. A rubber mold stress cone having a conical tapered surface inserted between the epoxy insulation cylinder 5 and the insulators 1a, 1a 'of the cables 1, 1'which are stripped from both sides.
6 and 6'are formed of conductive portions 6a and 6a 'formed of conductive rubber on the left and right rear portions, respectively, to alleviate the electric field, and the back portions 6b and 6b' of the left and right conductive portions 6a and 6a 'are protected by copper pipes. Spring units 8,8 'attached to the left and right ends of 7, push fittings 9,9'
The structure is such that it is pressed so as to be crimped by a constant load.

However, since the structure is unitized and assembled in this way, the inside becomes a sealed structure, so the epoxy insulating cylinder 5
Between the rubber mold stress cones 6 and 6'and between the rubber mold stress cones 6 and 6'and the cable insulators 1a and 1a '.
It was not possible to confirm whether the interface condition between and was normal. In order to confirm this interface state, it is important to detect the partial discharge of the prefabricated type connection part, but a method for this has not existed until now.

[Problems to be Solved by the Invention] In the prefabricated type connection part, a rubber mold stress cone is attached from the left and right to an epoxy insulating cylinder (unit) containing a metal embedded electrode, and the back surface of the rubber mold stress cone is attached. It is constructed by applying a pushing load with a spring unit. In this way, since it is configured by combining parts, it is necessary to check whether the interface between the epoxy insulation cylinder and the rubber mold stress cone or the interface between the rubber mold stress cone and the cable insulator is normal, and for a long time. It was necessary to judge whether the insulation characteristics did not deteriorate when used.

However, there is a problem that there is no method to detect the discharge pulse due to partial discharge and evaluate whether the interface between the rubber mold stress cone and the epoxy insulating cylinder or the interface between the rubber mold stress cone and the cable insulator is in a normal state. there were.

The present invention has been made in view of such a point,
An object of the present invention is to provide a method for detecting partial discharge of a prefabricated type connection portion for a CV cable.

[Means for Solving the Problem] The present invention further includes a main electrode having a length capable of covering an embedded electrode in a conductive layer on the outer diameter surface of an epoxy unit used as a main insulator of a prefabricated type connecting portion, and A ground electrode at the end is provided via an insulator of a prescribed length, and a plurality of metal measuring electrodes are provided on the main electrode. It is a partial discharge detection method for a prefabricated type connection portion for a CV cable, which is connected and a high frequency current pulse from a measurement electrode is detected by a partial discharge detector.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing only the upper half of the prefabricated intermediate connecting portion, and FIGS. 3 (a) and 3 (b) show the details of the left and right measuring electrodes of the prefabricated intermediate connecting portion. It is a figure. The same members shown in FIG. 2 explained in the above-mentioned prior art will be explained by giving the same reference numerals. That is, a conductive layer main electrode 10 having a length to cover the embedded electrode 4 embedded in the epoxy unit 5 is provided on the outer peripheral surface of the epoxy unit 5 of the prefabricated intermediate connection portion, and the conductive electrode main electrode 10 is spaced from the main electrode 10 at a constant interval. The conductive layer ground electrodes 11, 11 on the surfaces of both ends of the epoxy unit 5.
Is provided. Then, as shown in FIGS. 3A and 3B, metal measuring electrodes 13, 13 are attached to the surfaces of the left and right end portions of the conductive layer main electrode 10, and the measuring electrodes 13, 13 are attached to the measuring electrodes 13, 13. Is
Connect the measurement leads 14 and 14, respectively. Although not particularly shown, the ground electrodes 11, 11 are grounded via the protective copper tube 7 or the like.

Next, a case where the intermediate connection portion is formed by using the epoxy unit 5 formed as described above will be described. First,
The end portions of the CV cables 1, 1'to be connected are stripped off to expose the cable conductors 2, 2 ', and the outer periphery of the cable conductors 2, 2'is covered and connected. An epoxy unit 5 having an embedded metal fitting 4 annularly embedded in the inner surface of one of the CV cables 1'which has been previously inserted through the outer periphery of the connection portion is moved and covered, and the projection portion of the connection pipe 3 is provided. The projections of the embedded metal fitting 4 are brought into contact with each other for connection. Next, the rubber mold stress cones 6 and 6'having tapered surfaces at the tips, which are also inserted into the CV cables 1 and 1'in advance, are attached from the left and right to the epoxy unit 5 and the CV cable insulators 1a and 1a 'outer periphery. Insert between. Then, the outer circumference of the epoxy unit 5 is covered with a halved protective copper tube 7, and rubber inserted by the pressing metal fittings 9 and 9'of the spring units 8 and 8'attached to the left and right ends of the protective copper tube 7. The back surfaces of the mold stress cones 6 and 6'are pressed against each other so that a load is applied to the central side of the cones to integrate them.

On the outer peripheral surface of the epoxy unit 5, a main electrode 10 of a conductive layer is formed in a length covering the embedded metal fitting 4, and a plurality of metal measuring electrodes 13, 13 are formed in advance on the surfaces of both ends of the main electrode 10. From these, the measurement lead wires 14 and 14 are drawn out through the holes of the protective copper tube 7 and connected to the detection impedance 15. In addition, the epoxy unit 5 is provided on both sides of the main electrode 10 on the outer periphery of the epoxy unit 5 with a constant interval.
Ground electrodes 11, 11 are formed in advance on the outer periphery of the end portion of the.

Therefore, the discharge pulse received at the measuring electrodes 13, 13 will pass through the measuring leads 14, 14 to the detection impedance 15
Is detected by the partial discharge pulse measuring device 16 via. In addition, the voltage applied across the capacitor 18 is measured by the waveform measuring device 17
Observe by. There are two rubber mold stress cones on the left and right by providing the measurement electrodes 13 on the left and right.
It is possible to determine in which of 6 and 6'the partial discharge has occurred. Further, by comparing the voltage waveform of the CV cable observed by the waveform measuring device 17 and the measured waveform of the partial discharge pulse, it is possible to determine at which position of the CV cable the partial discharge has occurred. The waveform measuring device 17 may detect the current component via a current transformer (CT).

[Effects of the Invention] As described above, according to the present invention, the main electrode and the ground electrode are provided in advance on the outer periphery of the epoxy unit of the prefabricated intermediate connection portion for the CV cable, and the partial discharge measurement lead wire is provided on the main electrode. Is connected to detect the partial discharge of the prefabricated intermediate connecting portion, the insulation diagnosis of the prefabricated intermediate connecting portion can be performed even during operation. Further, by comparing the partial discharge pulse measuring device and the voltage waveform measuring device, it is possible to determine where in the voltage phase corona occurs. Furthermore, by installing one metal measuring electrode on each of the two rubber mold stress cones, it is possible to easily measure from which rubber mold stress cone the corona is coming out. Insulation diagnosis of prefabricated type connection for CV cable is possible.

Furthermore, since the ground electrode is provided on the end surface of the epoxy unit at a fixed distance from the main electrode, noise intrusion from both sides of the epoxy unit can be effectively prevented, and as a result, highly accurate partial discharge detection can be performed. Can be expected.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a partial discharge detection method for a prefabricated intermediate connecting portion for a CV cable according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a structure of a conventional prefabricated intermediate connecting portion. FIGS. 3 (a) and 3 (b) are detailed views of the vicinity of the metal measuring electrode of the prefabricated intermediate connection for CV cable shown in FIG.

[Explanation of symbols]

 1,1 ′ …… CV cable 1a, 1a ′ …… CV cable insulator 2,2 ′ …… Cable conductor 3 …… Connecting tube 4 …… Embedding bracket 5 …… Epoxy unit 6,6 ′ …… Rubber mold Stress cone 7 …… Protective copper tube 8,8 ′ …… Spring unit 9,9 ′ …… Pressing metal fitting 10 …… Main electrode 11 …… Grounding electrode 13 …… Metal measuring electrode 14 …… Measuring lead wire 15 …… Detection impedance 16 …… Partial discharge pulse measuring device 17 …… Waveform measuring device 18 …… Capacitor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-1475 (JP, A) JP-A-63-131079 (JP, A) Actually opened 61-117538 (JP, U) Actually opened 2- 68629 (JP, U) Actually opened 56-92426 (JP, U) Actually opened 62-125322 (JP, U)

Claims (1)

(57) [Claims] 1. A prefabricated type connecting portion formed by combining an epoxy unit of a connecting portion for a CV cable and a rubber mold stress cone and applying a constant load with a spring, and a large embedded electrode on the outer diameter surface of the epoxy unit. A main electrode is provided so as to cover the part, a ground electrode is provided on the end surface of the epoxy unit at a constant interval from this main electrode, and a measurement lead wire is provided on the left and right ends of the main electrode via metal measurement electrodes. A method for detecting partial discharge of a prefabricated type connecting portion for a CV cable, characterized in that the partial discharge is detected by a partial discharge detector by connecting the measuring lead wire to a detection impedance.