JPH03111773A - Inspection of prefabricated connecting part for cv cable - Google Patents

Abstract

PURPOSE:To make it possible to perform a test under the assembled state of components by attaching a simulated cable to an epoxy unit as a sample under test, arranging the cable in a gas insulated test device, applying a high voltage, and detecting a partial discharging level. CONSTITUTION:Metal pipes 21 and 21' are covered with an epoxy resin, and simulated cables 20 and 20' are formed in rod shapes. Electric-field shielding parts 20a and 20a' having large diameters are formed at the right and left parts and inserted from the right and left sides of the epoxy unit 4 so that the parts are in contact at the central part. Then, rubber molded stress cones 5 and 5' are inserted from the right and left sides. The cones are compressed with spring units 8 and 8' so that the cones are in close contact with the unit 4 and the cables 20 and 20'. Thus the sample under test for the connecting part is assembled. The sample under test is mounted on a truck 30 and conveyed into a truck 31 constituting a partial-discharge measuring device. The inside of a case 32 of the truck 31 is filled with insulating gas (SF6) to a specified pressure and sealed. A high voltage power source 33 is operated, and a specified high voltage is applied to the connecting part of the sample under test. Then, the discharge level of the unit 4 is detected with a partial-discharge detector 35.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for inspecting prefabricated connections for CV cables.

[Prior art] The connection part for CV cable from 154kV to 275kV is
The tape winding mold method involves laminating and winding polyethylene tape containing a crosslinking agent and crosslinking molding, or the extrusion molding method uses an extruder to extrude and crosslink polyethylene containing a crosslinking agent in order to reduce the level of foreign matter to the level of cable insulation. It has been applied to railway lines. These tape-wrapping mold systems and extrusion mold systems both require a heating crosslinking step to assemble the connection portions, which poses a problem in that the assembly time is long.

Therefore, a prefabricated connection section, in which unitized parts are assembled and connected, has been proposed and is now being used in practice.

Hereinafter, the configuration of this prefabricated connecting portion will be explained with reference to the drawings. FIG. 3 is a sectional view showing only the upper half of the structure of the prefabricated connecting portion. CV cable to connect,
The ends of cable conductors 1' are stripped off in steps to expose cable conductors 1a and la, which are butted together, covered with conductor sleeve 2, and compressed for connection. A cylindrical epoxy unit 4 with a tapered inner surface is formed by embedding a metal high-voltage electrode 3 with a T-shaped cross section that has been inserted into the cable in advance into this connection part.
The conductor sleeve 2 and high-voltage electrode 3 are connected by a connecting ring 11, and an annular stopper 10 is placed between the inner peripheral surface of the epoxy unit 4 and the insulator of the cables 1 and 1'.
10' and secure. This stopper 10.1
0' is to prevent the tip of the rubber mold stress cone from getting between the epoxy unit 4 and the insulators of the cables 1 and 1'.0 Next, insert the cables 1 and 1' from the left and right to the center. a cylindrical rubber molded stress cone 5 with a hole formed therein and a tapered surface at the tip;
5' is fitted so as to abut against the tapered surface of the epoxy unit 4. This rubber mold stress cone 5,5'
Rubber molded stress cone conductive layer 6, 6 on the back side of
' are integrally molded. Then, a connection case 9 is attached onto the epoxy unit 4, and spring units 8, 8' are provided at the left and right ends of this case 9.
Rubber mold stress cone 5,
Assemble by pressing the conductive layer portion on the back side of 5'.

In this way, this prefabricated connection part combines an epoxy unit made of epoxy resin for electrical insulation, a rubber molded stress cone made of ethylene-propylene rubber (EPR), and silicone rubber, and is compressed by pressing with a spring unit. This ensures electrical insulation between the epoxy unit and the CV cable insulation.

[Problems to be Solved by the Invention] By the way, electrical insulation of each component forming such a prefabricated connection part is inspected to ensure electrical insulation of the connection part, but epoxy Until now, there has been no method of testing the combined state of the unit and rubber molded stress cone using a corona test or the like.

As described above, the problem with which the partial discharge test (commercial frequency partial discharge test), which is an electrical inspection method, could not be performed when the parts of the prefabricated connection section for CV cables were assembled in actual use state was due to Prefabricated connections are large and may require special test equipment, but there is no method to improve the detection level of partial discharge tests, and because high voltage is applied, termination processing is required. This is thought to be due to the lack of a proper configuration and structure for the discharge test.

This invention was made in view of the above points, and C
An object of the present invention is to provide an inspection method that allows a partial discharge test to be performed on a prefabricated connection part of a V cable in a state in which each component is actually assembled.

[Means for Solving the Problems] In this invention, a prefabricated type is used as a connection part for a CV cable, which is constructed by combining a rubber molded stress cone with an epoxy unit in which a high voltage shield electrode is embedded, and compressing this with a spring unit. In the inspection of the assembled state of the epoxy unit and rubber molded stress cone at the connection part, two epoxy dummy cables were constructed with an electric field shielding structure at one end and a prescribed rubber molded stress cone was placed at the other end. Attach it to the unit and assemble it into the actual assembled state with a spring unit to use as a test sample; [b] Place the assembled test sample in a case in a gas insulation test device and fill it with insulating gas at a predetermined pressure;
This is a method for inspecting a prefabricated connection part for a CV cable, characterized in that electricity is applied from a high-voltage power source and detected by a partial discharge detector of a test sample.

[Example] Hereinafter, the present invention will be described in detail based on the drawings. 1st
The figure is a sectional view showing the structure of the method for inspecting a prefabricated connection part for a CV cable according to the present invention, and the same members shown in FIG. 3 are given the same reference numerals and will be explained. That is, the epoxy unit 4 constituting the prefabricated connection part is a cylindrical member with a hole 4b in the center through which the cable is inserted, and a tapered surface 4a formed on the inner surface from both sides, and a T-shaped cross section inside the center part. An annular metal high-voltage electrode 3 is integrally formed by molding. In this epoxy unit 4, the ends of the connecting portions of the CV cables are actually inserted from both sides, but in this testing method, epoxy dummy cables 20, 20' are inserted. That is, the simulated cable 20, 20' is formed into a rod shape by coating a central metal pipe or conductive plastic pipe 21, 21' with epoxy resin, and has a large diameter electric field at the left and right ends. Shielding portions 20a and 20a' are formed, respectively. The tip of the metal pipe 21.2
A concave end fitting 22.22' screwed to the end fitting 22.22' is attached, and a threaded portion 22a is also provided on the concave inner surface of the end fitting 22.22'.

22a' is formed. This tip fitting 22゜22'
includes an annular connecting ring 2 having a flange portion that comes into contact with the protruding portion 3a of the metal high voltage electrode 3 of the epoxy unit 4;
3.23' are screwed into threaded portions 22a and 22a' provided on the concave inner surface of the tip fittings 22 and 22', respectively. Left side connecting ring 23
A threaded portion 23b is formed on the inner circumferential surface for fixing the left side simulated cable 20, and the threaded portion 25a at the tip of the copper conductor fixing fitting 25 is screwed to this threaded portion 23b. It is formed. This conductor fixing fitting 2
A flange portion 25b and a threaded portion 25c to which a nut 26 is attached are formed on the right end side of 5.

Next, the simulated cable 20.2 formed in this way
The case of assembling a test sample of a connection part to be inspected using 0' will be explained. Left and right simulated cables 20.20'
A tip end fitting 22, 22' and a connecting ring 23, 23' are attached to the tip end portions of the two, respectively, by screws. and,
They are inserted from the left and right sides of the epoxy unit 4 so as to abut each other at the center. At this time, the connection ring 23' of the right simulated cable 20' is provided with a notch that engages with the protrusion 3a of the high voltage electrode 3 of the epoxy unit 4, and the connection ring 23.23' is accurately These connecting rings 23, 23'
An annular stopper 10.10' is inserted into an annular space formed by the inner surface 4b of the epoxy unit 4 and the outer periphery of the left and right dummy cables 20.20' so as to abut the connection rings 23° and 23'. These stoppers 10.1
0' is to prevent the tip of the rubber mold stress cone from entering. Insert the conductor fixing fitting 25 into the center of the simulated cable 20' on the right, and screw the threaded part 25a at the tip into the threaded part 23b provided on the inner periphery of the connection ring 23 attached to the tip of the simulated cable 20 on the left. Fix it with. Then, by fitting and screwing the nut 26 into the threaded part 25c provided at the right end of the conductor fixing fitting 25, the flange part 25b is attached to the right side of the simulated cable 25.
Abutting the right end of ', the simulated cable 20.20' is fixed.

Next, the conical rubber molded stress cones 5.5' are inserted from the left and right sides respectively, and the back surfaces of the spring units 8, 8 provided at the ends of the connection case 9 attached to the outer periphery of the epoxy unit 4 are inserted. ’ push metal fitting 7
, 7' are brought into contact with each other and pressed, and the rubber mold stress cones 5, 5' are attached to the epoxy unit 4 by the force of the spring.
The test sample of the connection part is assembled by closely contacting the outer periphery of the epoxy unit 4 and the simulated cable 20, 20' with the tapered surfaces 4a, 4a'.

The connection portion of the test sample thus formed is placed on a trolley 30 and carried into a trolley 31 constituting a partial discharge measuring device as shown in FIG. This partial discharge test device consists of a cart 31 equipped with a high voltage power source 33 and a case 32, and on the left side of the high voltage power source 33 there is a conductor fixing metal fitting for the simulated cable 20' on the right side of the connection part, which is the test sample. A terminal portion 33a directly connected to the end portion of 25 is provided for connection. Also,
A measurement lead wire 33 is connected from a predetermined position of the epoxy unit 4 to a connection connector 34 of the case 32, and this connector 34 is connected to a partial discharge detection device 35.
Move the case 32 to the right side and attach it to the wall of the high voltage power supply 33.
The openings of the case 32 are brought into contact with each other so as to be airtight, and an insulating gas such as SF6 is sealed and filled to a predetermined pressure from a supply port (not shown) provided in the case 32. Then, the high voltage power supply 33 is operated to apply a predetermined high voltage to the connection portion of the test sample, and the partial discharge level of the epoxy unit 4 is detected by the partial discharge detector 35.

In the above example, the partial discharge measuring device measures one connection portion as a test sample, but it may be configured to measure a plurality of partial discharge measuring devices in parallel.

[Effects of the Invention] As explained above, according to the method for inspecting prefabricated connections for CV cables of the present invention, it is possible to perform a partial discharge test by assembling the epoxy unit and rubber molded stress cone in the state in which they will actually be used; , a prefabricated connection part with improved inspection performance and high reliability can be obtained.

■Easy to assemble and handle for testing.

■One or more prefabricated connections can be inspected at the same time.

It has excellent effects such as

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the configuration of an inspection device for prefabricated connection parts for CV cables showing an embodiment of the present invention, Fig. 2 is a side view of a partial discharge measuring device, and Fig. 3 is a prefabricated connection part. FIG. 3 is a cross-sectional view showing only the upper half of the structure of the part. 4... Epoxy unit 5.5'... Rubber mold stress cone 7.7'.
... Push metal fitting 8.8' ... Spring unit 9 ... Connection case 10.10' ... Stopper 20.20' ... Epoxy simulated cable 20 a,
20 a'...Electric field shielding part 30.31...Dolly 32...Case 33...High voltage power supply 35...Partial discharge detector

Claims (2)

[Claims] (1) Assembly of a prefabricated epoxy unit and rubber molded stress cone for a CV cable connection, which consists of a rubber molded stress cone combined with an epoxy unit embedded with a high voltage shield electrode, and compressed by a spring unit. In the inspection of the condition, [a] two epoxy dummy cables, one end of which is constructed with an electric field shielding structure and the other end of which has a prescribed rubber molded stress cone, are attached to the epoxy unit, and the spring unit is used for actual assembly. [b] This assembled test sample is placed in a case in a gas insulation test device, and insulating gas is filled with a predetermined pressure.
A method for inspecting a prefabricated connection part for a CV cable, characterized by applying electricity from a high-voltage power source and detecting partial discharge in a test sample with a detector. (2) The method for testing a prefabricated connection part for a CV cable according to claim 1, wherein the gas insulation testing device has a structure in which a case is integrally attached to a cart.