JP3196995B2 - Partial discharge test equipment for cylindrical insulators - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for testing partial discharge of a long hollow cylindrical insulator mainly used for high-voltage equipment.

[0002]

2. Description of the Related Art At present, gas insulation equipment using SF ₆ gas is widely used in substations and the like. Gas-insulated equipment is a type of high-voltage, large-capacity equipment that can be manufactured in a small size with high reliability. It is widely used today as a key for power transmission and distribution equipment. On the other hand, a high voltage device called a bushing connects between the power transmission line and the gas insulation device.

[0003] Various types of bushings have been put into practical use due to their insulating structure. Above all, gas bushings using SF ₆ gas as an insulating medium are easy to handle because of their light weight and simple structure,
It is one of the indispensable devices in the configuration of the gas insulation device.

[0004] The gas bushing is formed by pressing S
Although the insulation performance inside the bushing is improved by enclosing the F ₆ gas, if the insulator is damaged for any reason, the insulator may be scattered by the gas pressure inside.

[0005] In particular, from the viewpoint of further improving the reliability of gas-insulated equipment in recent years and ensuring safety for operators, a gas bushing has been required to have a structure for suppressing scattering in case of porcelain tube failure. .

[0006] In order to meet such needs, there has been proposed an explosion-proof construction in which an explosion-proof inner cylinder is housed in an insulator tube as shown in Japanese Patent No. 1303003. According to this example, the amount of insulating gas to be filled between the insulator tube and the explosion-proof inner cylinder can be minimized, and even if the insulator tube is broken, the scattering distance of the insulator tube fragments can be reduced, thereby improving the disaster prevention effect. be able to.

As an actual bushing structure, a scattering-suppressing gas bushing disclosed in Japanese Patent Application No. 5-10810 has been proposed. This is shown in FIG. In this method, the gas volume between the insulator and the insulator is reduced by inserting a cylindrical insulator 20 made of FRP inside the insulator, thereby significantly reducing the scattering distance, and has already been put to practical use. .

[0008]

The above-mentioned shatter-suppressing type bushing secures desired insulation performance and shatter-suppressing function by inserting a cylindrical insulator made of FRP into the insulator tube. However, the present insulator has the following problems in securing electrical insulation performance.

Hereinafter, as an example of a cylindrical insulator, 1000 kV
Take up the FRP insulators used for power transmission gas bushings. This is shown in FIG. The structure is such that the FRP insulating tube 20 is inserted into a long cylindrical porcelain insulator tube of about 12 m, and is characterized by being extremely elongated as easily imagined from its shape. It is extremely important to inspect in advance whether there is an electrical abnormality in the insulator in order to ensure reliability. Normally, a partial discharge test is performed to determine the presence or absence of an electrical abnormality. However, when an attempt is made to actually perform a partial discharge test on such a long cylindrical insulator, as described below, it is extremely large. With difficulty.

For example, as is widely practiced in the past, when electrodes are attached to both ends of an insulator and the electrical insulation characteristics of the insulator alone are inspected over the entire length, the electrical stress applied to the insulator is long. Due to the size of the scale, it is strongly affected by the surroundings, and the direction and magnitude of the electric field greatly vary depending on the location. For this reason, there is a problem that only local verification can actually be performed. In addition, a voltage of 1100 kVrms, which is equivalent to the actual test voltage, is required, and the test itself is extremely large. In addition, it is necessary to secure a sufficient insulation distance as a test facility, and a large test space is required. Furthermore, there is a technical problem that even if an attempt is made to perform the partial discharge test with high sensitivity, sufficient detection sensitivity cannot be obtained due to the length of the test. For this reason, the partial discharge test using the FRP insulating cylinder alone was practically impossible.

Therefore, in the conventional method, the FRP insulating cylinder must be assembled as a bushing first without conducting a sufficient verification test, and the test must be performed in a completed state. For this reason, if any abnormality is found, the test itself must be restarted from the beginning,
There was a problem that a great many inconveniences occurred.

The present invention has been proposed to solve the above-mentioned drawbacks, and an object of the present invention is to provide an apparatus for testing a partial discharge of a long cylindrical insulator.

[0013]

SUMMARY OF THE INVENTION According to the present invention, there is provided a columnar conductor electrode axially inserted through a hollow cylindrical insulator, and the hollow conductor electrode is arranged so that the columnar conductor electrode is substantially parallel to the inner surface of the hollow cylindrical insulator. Support means for supporting the cylindrical insulator, an electrode portion disposed outside the hollow cylindrical insulator and movable in the axial direction of the columnar conductor electrode, and a voltage generator for applying a predetermined voltage to the electrode portion And characterized by comprising:

[0014]

According to the above construction, the hollow cylindrical insulator can be
By applying an equivalent electric field to the electrodes provided to simulate the electric field generated during the actual test, the partial discharge test can be performed at a voltage much lower than the actually used voltage. Furthermore, since the portion to which the electric field is applied is limited to a local portion, the source of the partial discharge can be specified by moving the electrode or rotating the cylindrical insulator. In addition, by making the insulating medium a medium with higher dielectric strength than air,
A more sensitive partial discharge test can be performed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a cylindrical insulator partial discharge test apparatus according to the present invention. In FIG. 1, a hollow cylindrical insulator 1 is
The turntables 6a and 6b can rotate in the circumferential direction. A cylindrical conductor 2 is inserted inside the cylindrical insulator 1 and the lower side faces are formed of insulating supports 10 and 11.
, And is grounded via a partial discharge detection impedance 7. A first electrode 3 and a second electrode 4 are provided outside the insulating cylinder 1, and these electrodes are integrally formed by a gantry 12. In addition, the first electrode 3 is supported by the support 12 by the insulating support 13.
And is insulated. The first electrode 3 and the second electrode 4 can be moved in the axial direction of the cylindrical insulator by the gantry 12. The first electrode 3 is connected to an AC power supply 5. On the other hand, the second electrode 4 is grounded via the partial discharge detection impedance 8.

When the cylindrical insulator 1 has a conical shape as in the representative example shown in FIG. 2, that is, when the cylindrical insulator has a shape having a different diameter in the axial direction, the cylindrical insulator 1 has a cylindrical shape. To reduce the distance between the inner and outer electrodes of the insulator as much as possible and to minimize the change in the electric field when the electrodes move in the axial direction, the center axis of the conductor inserted inside the cylindrical insulator is The relative arrangement of the insulating cylinder and the electrodes is devised so as to be substantially parallel to the side surface of the cone contacting the inner surface of the insulator.

The test apparatus configured as described above is herein supposed to be a device using a three-electrode method. According to this embodiment, when a high voltage is applied between the first electrode 3 and the conductor 2, an electric field is applied in the direction of the penetrating layer of the cylindrical insulator. In this case, if there is any electrical defect such as voids, peeling, or inclusion of foreign matter, partial discharge occurs here. The electric signal generated at this time can be detected by the detection impedance 7.

Further, since the first electrode 3 and the second electrode 4 can generate an electric field in the axial direction of the cylindrical insulator, it is possible to find an electric defect existing in the direction along the layer. The partial discharge signal generated in this case can be detected by the detection impedance 8. Actually, the electric field distribution in the trans-layer direction and the layer-wise direction changes variously depending on the geometrical arrangement of these electrodes. Therefore, it is necessary to analyze the details of the electric field distribution by a calculation method using an electronic computer. However, even in such a case, it is clear that the present test method enables a partial discharge test in both a layered direction and a layered direction of the cylindrical insulator under a certain range of electric field stress. It is.

Since the place where the electric field is applied is limited to the vicinity of the first and second electrodes, the movement of the electrode or the rotation of the cylindrical insulator is applied to the entire cylindrical insulator as described above. By performing the test, the partial discharge test can be performed on all the parts. As a result, when a partial discharge occurs, it has a great feature that the place where the partial discharge occurs can be specified.

Further, when the diameter of the cylindrical insulator is different from the axial direction, the center axis of the conductor inserted into the cylindrical insulator may be in the form of a conical side surface in contact with the inner surface of the cylindrical insulator. By eccentricizing the axis of the cylindrical insulator so as to be substantially parallel to the above, the magnitude of the electric field applied to the cylindrical insulator can be kept within a certain allowable range.

Further, the magnitude of the voltage required in this case is the sum of the voltage applied to the thick portion of the cylindrical insulator and the voltage applied to the gap in the other portion. Since the gap can be minimized, the voltage can be significantly reduced as compared with the case where the entire cylindrical insulator is tested. Therefore, there is an advantage that the test can be easily performed.

As described above, according to the present invention, it is possible to perform a partial discharge test on a long tubular insulator, which has been difficult to test in the past, and to easily remove electrical defects. It becomes possible to discover.

At first, the above description has been made on the assumption that the test is performed in the atmosphere. However, in actuality, the influence on the partial discharge test due to the temperature and humidity of the air and dust contained in the air are considered. Is often a concern. In such a case, such a problem can be solved by installing a test device (at least an electrode portion and a cylindrical insulator) in an insulating gas, for example, SF ₆ gas or transformer oil. Particularly when testing in SF ₆ gas, the insulating properties of the gas itself are excellent, so it is not necessary to consider the effect of partial discharge generated from the test equipment side, and the partial discharge of the insulator itself can be performed with extremely high accuracy. Can be measured.

Next, when pure water is used as the insulating medium, the relative dielectric constant of water is larger than that of the insulator, so that
Testing can be performed using lower voltages. Although the shapes of the first and second electrodes have not been described in the above-described embodiment, it is convenient for testing to use a part of the spherical electrode or the ring electrode. In this case, it is of course convenient if the electrodes are integrally formed and a gap length adjuster is provided so that the distance between the electrodes in the vertical and horizontal directions can be adjusted in advance.

As for the method of rotating the cylindrical insulator, the case where a rotary table is used has been described here, but there is no problem even if other methods such as rotating both ends using a support bracket or the like are used.

It is clear that applying an insulating coating or an alumite treatment to the electrode is effective in preventing partial discharge from the electrode and is also effective for the present test apparatus.

The test apparatus can automate the rotation of the cylindrical insulator, the movement of the first and second electrodes, or the partial discharge test, thereby enabling a more reliable partial discharge test. Becomes

[0028]

As described above, according to the present invention, it is possible to apply an electric field equivalent to that in an actual use state to a long tubular insulator. As a result, the partial discharge test can be easily performed, and the electrical insulation performance of the long tubular insulator can be inspected in advance.

[Brief description of the drawings]

FIG. 1 is an illustrative view of one embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG. 1;

FIG. 3 is an illustration of a use example of a cylindrical insulator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cylindrical insulator 2 ... Conductor 3 ... 1st electrode 4 ... 2nd electrode 5 ... AC power supply 6a, 6b ... Turntable 7 ... Detection impedance 8 ... Detection impedance 10 ... Insulation support 11 ... Insulation support
12 ... Base 20 ... FRP insulation tube

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Iwao Oshima 2-1 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Hamakawasaki Plant, Toshiba Corporation (56) References JP-A-62-24166 (JP, A) JP-A-4-289681 (JP, A) JP-A-62-24167 (JP, A) JP-A-7-41476 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) G01R 31/12

Claims (5)

(57) [Claims] A columnar conductor electrode axially inserted through a hollow cylindrical insulator, and the hollow cylindrical insulator is supported such that the columnar conductor electrode is substantially parallel to an inner surface of the hollow cylindrical insulator. A supporting means, an electrode portion disposed outside the hollow cylindrical insulator and movable in the axial direction of the columnar conductor electrode, and a voltage generating portion for applying a predetermined voltage to the electrode portion. Characteristic partial discharge test device for cylindrical insulators. 2. The apparatus according to claim 1, wherein said supporting means rotatably supports said hollow cylindrical insulator along an outer periphery of said columnar conductor electrode. 3. The apparatus for testing partial discharge of a cylindrical insulator according to claim 1, wherein said electrode portion is composed of a pair of electrodes arranged so as to be substantially parallel to and separated from and opposed to said columnar conductor electrode. 4. The apparatus for testing partial discharge of a cylindrical insulator according to claim 1, wherein the electrode portion and the columnar conductor electrode are coated with an insulating material. 5. The partial discharge test apparatus for a cylindrical insulator according to claim 1, wherein at least the hollow cylindrical insulator, the columnar conductor electrode, and the electrode portion are arranged in an insulating medium atmosphere.