JPH07294591A - Electrical testing method - Google Patents

Abstract

PURPOSE:To obtain necessary data and to also make the electrical test of the cables themselves possible to be performed by testing the enhanced insulation body part of a connection box for connecting different kinds of cables under a condition closer to an actual use. CONSTITUTION:The breakdown voltage test of an enhance insulation body 10 with a connection terminal 10A for connecting CV cable and a connection terminal 10B for OF cable is performed. An oil-dipped paper 15 is wound around a CV cable 1-3 for electrification and a bellmouth 16, etc., are fitted as needed as a terminal for pseudo OF cable, which is then fitted to the connection terminal 10B for OF cable. The connection terminal 10A for CV cable arranges electric field with a spherical electrode 23, thus forming a similar electric field as fitting of the OF cable to the connection terminal 10B for OF cable for testing. Also, other high-electric-field part can be fully and electrically connected to prevent unneeded corona discharge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric test method suitable for an electric test of an insulation reinforcement used in a junction box of a power cable and the power cable itself.

[0002]

2. Description of the Related Art A connection box used for a heterogeneous cable joint has a CV cable connection terminal on one side and an OF cable connection terminal on the other side. In this case, the end of the CV cable is attached to the connection terminal for the CV cable together with the rubber mold stress cone, while the end of the OF cable in which oil-impregnated paper is wrapped around the connection terminal for the OF cable and insulated and reinforced by a bell mouth or the like is used. It is installed.

Conventionally, the dielectric strength test of such a heterogeneous cable connection box has been performed in an insulating gas. That is, the insulation reinforcement portion of the connection box is taken out, and the CV cable for charging is attached to the CV cable connection terminal. Then, the required test voltage is applied in the insulating gas.

[0004]

By the way, the above-mentioned conventional electric test method has the following problems to be solved. When an electrical test is performed on a cable connection box in an insulating gas, the electrical characteristics of the insulating gas become the test limit. That is, it is not possible to apply a high electric field above a certain level. In addition, the electric field distribution is significantly different from the state of the junction box actually used. Moreover, corona discharge is generated over a wide range at the interface with the insulating gas, and it is difficult to detect a partial discharge or the like caused by a defect in the insulating reinforcing body itself.

The present invention has been made by paying attention to the above points, and tests the insulation reinforcement portion of a connection box for connecting different types of cables under conditions as close as possible to the use condition to obtain necessary data. The purpose is to provide an electrical test method. The present invention also aims to enable an electrical test of the cable itself by utilizing such a test method.

[0006]

According to the electrical test method of the present invention, an electrical test is performed on a junction box insulation reinforcement having at least one CV cable connection terminal and at least one OF cable connection terminal. In this case, oil-impregnated paper is wound around the terminal of the CV cable for voltage application to form a terminal for the pseudo OF cable, which is attached to the connection terminal for the OF cable, and for forming a uniform electric field on the connection terminal for the CV cable. The sphere electrode of No. 1 is attached, and a test voltage is applied to the junction box insulation reinforcement through the CV cable for charging.

In another electrical test method of the present invention, a junction box insulation reinforcement having at least two cable connection terminals is attached to the end of a cable line under test, and the junction box is subjected to the above test under test. Attach a spherical electrode for forming a uniform electric field to the open cable connection terminal that does not attach the cable,
The test voltage generating power supply is connected to one end of the cable line under test, and the test voltage is applied.

[0008]

In this method, the connection terminal for the CV cable and the OF
A withstand voltage test is performed on the insulation reinforcement with cable connection terminals. For the connection terminal for the OF cable, an oil impregnated paper is wound around the CV cable for voltage application, and a bell mouth or the like is attached as necessary to attach a terminal for the pseudo OF cable. CV
The connection terminal for the cable uses a spherical electrode to regulate the electric field. As a result, the same electric field as when a cable is attached to both connection terminals is formed, and the test can be performed. Further, the high electric field portion is sufficiently protected electrically, and unnecessary corona discharge or the like does not occur.

[0009]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of a main part showing an embodiment of an electric test method of the present invention. The insulation reinforcement 10 shown in this figure is housed inside a heterogeneous cable junction box (not shown). The insulation reinforcement body 10 is composed of an insulation block having a through hole in the center, and has a CV cable connection terminal 10A at one end and an OF cable connection terminal 10B at the other end.

A connecting conductor 13 is embedded in the center of the epoxy unit 11. This is configured such that the through holes of the epoxy unit 11 are divided into right and left, and the outer peripheral portion is embedded in the epoxy unit 11. A CV cable for voltage application 1-3 for applying a test voltage is inserted into the connection terminal 10B for the OF cable. C for this charge
The conductor 14 of the V cable 1-3 is electrically connected to the connecting conductor 13. It should be noted that this connection requires a relatively small amount of current to flow therethrough, and therefore a simple contact or the like may be used.

An oil-impregnated paper 15 is wound around the outer circumference of the power charging CV cable 1-3 to reinforce the insulation of the outer peripheral portion of the power charging CV cable 1-3. A bell mouth 16 is fitted on the outer circumference of the oil-impregnated paper 15 to adjust the electric field. The terminal portion of the charging CV cable 1-3 is surrounded by the protective case 22. Then, this is filled with insulating oil (not shown). on the other hand,
Unit fixing flanges 17 and 18 are attached to both ends of the epoxy unit 11, and these are connected and fixed by a unit fixing shaft 21.

A ball electrode 23 is attached to the side of the CV cable connecting terminal 10A of the connecting conductor 13. The spherical electrode 23 may be one that has been conventionally used for adjusting an electric field in various electric tests and the like.
In order to make this electric field uniform, the annular electrode 24 is also provided on the back surface of the unit fixing flange 17 facing the spherical electrode 23.
Is attached. Insulating gas is sealed inside the CV cable connection terminal 10A as required.
The electric field inside the CV cable connection terminal is adjusted by the spherical electrode 23 and the annular electrode 24. Therefore, there is no problem that the dielectric breakdown occurs first in this portion, and the partial discharge signal inside the insulation reinforcing body 10 which is the original test object cannot be recognized.

As described above, according to the present invention, the OF cable is not connected to the OF cable connection terminal 10B, but the pseudo OF cable terminal using the CV cable is mounted. In the case of such a test, the test result will be more accurate if a material or the like that is as close to the actual use state as possible is used. However, as can be seen from this figure, the terminal treatment of the OF cable and the mounting work thereof are much more complicated than the terminal treatment work of the CV cable. Moreover, there is a problem that it becomes difficult to repeatedly use the test material. In contrast to this, in the case of the present invention, since the CV cable is adopted, the attachment is easy and the repeated use becomes possible.

It should be noted that the connection to the OF cable connection terminal 10B is O
Since the CV cable is connected instead of the F cable, the electric field distribution is different from that of the OF cable, especially in the vicinity of the conductor of the cable. However, if the size of the spherical electrode 23 is changed from a small size to a large size in order, the size of the spherical electrode 23 is appropriately selected, and the electric characteristics can be made to be very similar to the electric characteristics when the OF cable is actually attached. Therefore, the selection of the radius of the spherical electrode 23 is an important factor in precisely performing this test. By using such a spherical electrode, the near electric field can be made sufficiently uniform.

FIG. 2 shows an example in which the terminal of the CV cable for charging is attached to the connection terminal for the CV cable this time. When testing the electrical characteristics of the CV cable connection terminal 10A side of the insulation reinforcing body 10, the configuration is as shown in this figure.
That is, on the side of the CV cable connection terminal 10A, a normal C
Use the V cable 1-4 for charging and attach it. This is insulated and reinforced by using a rubber mold stress cone 19 or the like according to the actual use state.

On the other hand, a spherical electrode 23 and an annular electrode 24 are arranged on the side of the OF cable connection terminal 10B to prevent corona discharge. As described above, according to the method shown in FIGS. 1 and 2, the electrical test of each connection terminal of the different type cable connection box is not performed by simply disposing the insulating reinforcing body in the insulating gas, but by performing the actual test. It can be carried out by a method according to the use condition. This allows a high voltage to be applied to any of the terminals, enabling a precise electrical test.

The next embodiment will be described with reference to FIGS. 3 and 4. If the above method is applied, the cable can be tested. For example, in the middle of construction of a CV cable for long-distance power transmission, there is a case where it is desired to test a cable, a cable connection portion or the like which has already been constructed and assembled. In such a case, one terminal is usually protected by a rising terminal or the like. However, the other end is cut off inside the manhole. It is very difficult to attach an end such as a rising end here considering the size of the manhole. Therefore, the following terminal structure is adopted.

FIG. 3 shows a vertical sectional view of the terminal structure of the cable under test. As shown, the end of the cable under test 26 is inserted into the insulation reinforcement 20. This insulation reinforcement 20 is configured to receive the CV cable terminations at both ends, and its partial components and roles are the same as those of the insulation reinforcement shown in FIGS. 1 and 2. The conductor 28 of the cable under test 26 is arranged in the through hole of the connecting conductor 27 arranged at the center thereof, and the compression terminal 29 is compression connected to the tip thereof. The spherical electrode 23 described in the other embodiments is attached to the compression terminal 29, and is arranged so as to be directed to the empty terminal side. The unit fixing flange 17 and the annular electrode 24 for sealing the empty terminals
The configuration of the above is exactly the same as that of the embodiment shown in FIGS.

At the end of the cable under test 26, as shown in the figure, the spring cone 5 presses the stress cone 6 against the epoxy unit 7 to obtain a certain electric characteristic. The cable under test 26 constitutes a part of the following cable line. FIG. 4 shows a schematic diagram of the cable line under test 30. This cable line under test 30 has a rising end 32 formed at a terminal, for example, and cables are connected to each other via a connection box 33 inside some manholes 35. The cable to be tested 26 arranged at the end is attached to the insulating reinforcing body 20 shown in FIG.

As a result, even if the cable line under test 30 is in an unfinished state, it is possible to apply a high voltage from the power supply 36 and appropriately perform an electric test by properly mounting the insulating reinforcing body 20. . In the embodiment shown in FIG. 4, a power source 36 is connected to the rising end 32 side where the work has been completed in advance to perform an electrical test. On the other hand, it is also possible to attach the terminal of the CV cable for voltage application by removing the ball electrode 23 and the unit fixing flange 17 on the empty terminal side shown in FIG.

FIG. 5 shows such a usage state. In this case, the power supply 3 is connected to one terminal of the insulating reinforcement 20.
6 will be connected, and the cable under test 26 will be connected to the other terminal. In the above example, the cable line under test includes the rising end, the cable, the connection box, etc., but these can be freely combined,
In addition, it is possible to perform an electrical test on each of them, for example, only a cable.

In this case as well, it is preferable that an insulating gas is filled in the space of the empty terminal including the spherical electrode 23 and the annular electrode 24. According to the embodiments shown in FIGS. 3 to 5, for example, a cable line that can be constructed over a long period of more than one year can be subjected to an electrical test relatively easily at any time, and moreover, like a manhole. It is also possible to connect the power supply to a narrow area. Therefore, it becomes possible to reduce the construction cost of the cable line and to enhance the reliability of the cable line itself.

The present invention is not limited to the above embodiments. Although the test of the connection box for connecting different types of cables has been described in the embodiments of FIGS. 1 and 2, the same test can be performed for the same type of cables, for example, the connection box for connecting the OF cables to each other.

[0024]

The electrical test method of the present invention described above is
When conducting an electrical test on a junction box insulation reinforcement having at least one CV cable connection terminal and an OF cable connection terminal, a pseudo OF cable is wound by winding oil-impregnated paper around the end of the CV cable for power application. A terminal is formed and attached to the connection terminal for the OF cable, a spherical electrode for forming a uniform electric field is attached to the connection terminal for the CV cable, and a test voltage is applied to the junction box insulation reinforcement through the CV cable for charging. By doing so, the test equipment can be constructed more easily than the case where the terminal of the OF cable is actually formed at the connection terminal for the OF cable and a test voltage is applied. Moreover, since the CV cable is used, there is an effect that the test equipment can be repeatedly used.

On the contrary, the end of the CV cable for charging is attached to the CV cable connection terminal, the spherical electrode for forming a uniform electric field is attached to the OF cable connection terminal, and the junction box is insulated via the CV cable. Since the test voltage is applied to the reinforcing body, the electrical test on the side of the CV cable connection terminal can also be performed at a high voltage in a state close to the actual use state. It should be noted that by selecting the diameter of the spherical electrode, it is possible to bring the pseudo OF cable end portion into a state close to that when an actual OF cable is attached.

If a connection box insulation reinforcement is attached to one end of the cable line and a spherical electrode is attached to the open cable connection terminal to which the cable under test is not attached, a test voltage is applied to one end of the cable line under test. It becomes possible to connect the generated power source and perform a test.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of an insulating reinforcing body which has been subjected to an electrical test method of the present invention.

FIG. 2 is a vertical cross-sectional view of another example of an insulating reinforcing body using the electrical test method of the present invention.

FIG. 3 is a longitudinal sectional view of a terminal portion of a cable under test which has been subjected to the electrical test method of the present invention.

FIG. 4 is an overall view of a cable line under test that has been subjected to the electrical test method of the present invention.

FIG. 5 is an overall view of another embodiment of the cable line under test which has been subjected to the electrical test method of the present invention.

[Explanation of symbols]

 1-3 CV cable for voltage application 10 Insulation reinforcement body 10A Connection terminal for CV cable 10B Connection terminal for OF cable 15 Oil-impregnated paper 16 Bell mouth 23 Ball electrode 24 Ring electrode

Claims (6)

[Claims] 1. When conducting an electrical test of a junction box insulation reinforcement having at least one CV cable connection terminal and at least one OF cable connection terminal, an oil is applied to the terminal of the CV cable for voltage application. Wrap the dip paper in the pseudo OF
A cable terminal is formed and attached to the connection terminal for the OF cable, a spherical electrode for forming a uniform electric field is attached to the connection terminal for the CV cable, and the connection is made via the CV cable for charging. An electrical test method comprising applying a test voltage to a box insulation reinforcement. 2. By selecting the diameter of the spherical electrode, the near electric field when the terminal for the pseudo OF cable is attached to the connection terminal for the OF cable can be made close to the near electric field when the true OF cable is attached. The electrical test method according to claim 1, which is characterized in that. 3. When performing an electrical test of a junction box insulation reinforcement having at least one CV cable connection terminal and at least one OF cable connection terminal, the CV cable connection terminal is subjected to A terminal of a CV cable for electric power is attached, a spherical electrode for forming a uniform electric field is attached to the connection terminal for an OF cable, and a test voltage is applied to the insulation reinforcement of the connection box via the CV cable for electric power application. An electrical test method characterized by applying. 4. A connection for an open cable of the connection box in which the cable under test is not mounted by mounting a connection box insulation reinforcement having at least two cable connection terminals on a terminal of a cable line under test. An electrical test method for a cable under test, characterized in that a spherical electrode for forming a uniform electric field is attached to the terminal, a test voltage generating power supply is connected to one end of the cable line under test, and the test voltage is applied. 5. When conducting an electrical test of a junction box insulation reinforcement having at least two CV cable connection terminals, one CV cable connection terminal is fitted with a terminal of a CV cable for voltage application, and the other A spherical electrode for forming a uniform electric field is attached to the CV cable connection terminal, and a test voltage is applied to the junction box insulation reinforcement through the charging CV cable. . 6. When conducting an electrical test of a junction box insulation reinforcement having at least two OF cable connection terminals, a pseudo OF is obtained by winding an oil-impregnated paper around the end of the CV cable for voltage application.
A cable terminal is formed and attached to the one OF cable connection terminal, a spherical electrode for forming a uniform electric field is attached to the other OF cable connection terminal, and the electric charge CV cable is used. And a test voltage is applied to the junction box insulation reinforcement.