JPH0378429A - Antenna device for monitoring insulation - Google Patents

Abstract

PURPOSE:To detect a high-frequency electromagnetic field generated by partial discharge in a vessel at the time of insulation deterioration with high sensibility from the outside of the vessel by arranging a slit antenna near an insulator positioned in the mutual joints of vessels or the joint of the vessel and a bushing under the state in which the circumferential direction of the insulator and the slit longitudinal direction are conformed. CONSTITUTION:A high-frequency electromagnetic field formed by partial discharge in an electrical equipment in which a charging section is surrounded by grounded vessels 1, 2 made of a metal is detected from the outsides of the vessels 1, 2 by a slit antenna 4, and the slit antenna 4 disposed near an insulator 3 positioned to the mutual joints of the vessels 1, 2 or the joints of the vessels 1, 2 and a bushing under the state in which the circumferential direction of the insulator 3 and the slit longitudinal direction are conformed. The direction of the detecting electric field of the slit antenna 4 and the direction of a high-frequency electric field leaking through the insulator 3 are conformed. Accordingly, the high-frequency electromagnetic field generated by partial discharge in the vessels 1, 2 at the time of insulation deterioration can be detected with high sensibility from the outsides of the vessels 1, 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to electrical equipment such as gas-insulated switchgear in which a live part is surrounded by a grounded metal container, in which internal parts that occur when insulation deteriorates. The present invention relates to an insulation monitoring antenna device for detecting discharge (corona discharge).

[Traditional techniques]

For example, a conventional insulation monitoring antenna device attached to a gas-insulated switchgear, etc., uses an insulating ring or other insulating ring interposed at the joint of a grounded metal conduit container 51, 52, as shown in FIG. A loop antenna 54 is placed near the body 53.

The conduit containers 51 and 52 have an insulator 53 sandwiched between the flanges 51a and 52a at the ends, and are fastened together with screws, etc., and the loop antenna 54 is attached to the 10th
In the figure, in the vicinity of the flange 51a, the conduit container 51
It is installed in an insulated state and wrapped around the conduit container 51.

Reference numeral 55 represents a charging section passing through the conduit containers 51 and 52, and 56 represents a coaxial cable for signal transmission.

In such an insulation monitoring antenna device, the loop antenna 54 detects a high frequency electromagnetic field generated by partial discharge due to insulation deterioration of the conduit vessel 51.52 from outside the conduit vessel 51.52. The degree of insulation deterioration within the conduit vessels 51 and 52 is detected based on the high frequency signal obtained from the conduit vessels 51 and 54. In this case, the loop antenna 54 detects leakage of the high frequency electromagnetic field within the conduit container 5152 from the insulator 53.

As another example, an insulation monitoring antenna device as shown in FIG. 11 has been proposed. In this insulation monitoring antenna device, a dipole antenna 57 is arranged along the outer peripheral surface of the insulator 53 with the circumferential direction of the insulator 53 and the longitudinal direction of the element aligned. In this case, the dipole antenna 57 is fixedly attached in a state where it is wrapped around the outer peripheral surface of the insulator 53.

In such an insulation monitoring antenna device, the dipole antenna 57 is connected to the insulator 5, which is a leakage point of the high frequency electromagnetic field.
3, it is possible to receive the highest level of high-frequency electromagnetic field leaking from the conduit containers 51 and 52.

[Problem to be solved by the invention]

The insulation monitoring antenna device shown in FIG.
Detection was performed using a loop antenna 54 wound around 1a, and since the loop antenna 54 was far from the insulator 53, the detection sensitivity was low.

In the insulation monitoring antenna device shown in FIG. 11, the high frequency electromagnetic field leaking from the insulator 53 is transmitted to the conduit container 51.
Due to the occurrence of partial discharge within 52, flanges 51a,
A potential difference occurs between 52a due to impedance mismatching, and a high frequency electromagnetic field is generated outside the insulator 53 due to this potential difference.
The direction of the electric field E is the thickness direction of the insulator 53, that is, the longitudinal direction of the conduit vessels 51 and 52. On the other hand, the direction of the electric field that can be detected by the dipole antenna 57 is the longitudinal direction of the element, that is, the direction perpendicular to the thickness direction of the insulator 53. Therefore, the dipole antenna 57 can hardly detect the high frequency electromagnetic field leaking from the insulator 53.
Detection sensitivity was extremely low.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an insulation monitoring antenna device that is capable of highly sensitively detecting a high-frequency electromagnetic field generated by partial discharge inside a container when insulation deteriorates from outside the container.

[Means to solve the problem]

The insulation monitoring antenna device of the present invention uses a slit antenna to detect a high-frequency electromagnetic field generated by partial discharge inside an electrical device whose live parts are surrounded by a grounded metal container from outside the container. ing. The slit antenna is arranged near an insulator existing at a joint between containers or a joint between a container and a bushing, with the circumferential direction of the insulator and the longitudinal direction of the slit aligned.

[For production]

According to the configuration of the present invention, when partial discharge occurs within the container due to insulation deterioration, a high frequency electromagnetic field is generated within the container. This high-frequency electromagnetic field leaks from the portion of the insulator that exists at the joint between the containers or the joint between the container and the bushing. In this case, the leaking high-frequency electromagnetic field is induced by a potential difference generated between the cocoon containers that sandwich the insulator or between the container and the bushing, and the direction of the electric field is perpendicular to the circumferential direction of the insulator.

On the other hand, a slit antenna has high detection sensitivity for electric fields in a direction perpendicular to the longitudinal direction of the slit, and when placed near an insulator with the longitudinal direction of the slit antenna aligned with the circumferential direction of the insulator, It can receive a high level of high-frequency electromagnetic field leaking from the body, and the direction of the electric field of the high-frequency electromagnetic field leaking from the insulator matches the direction perpendicular to the longitudinal direction of the slit of the slit antenna, which has high detection sensitivity for high-frequency electromagnetic fields. Therefore, high frequency leaks from the insulator 1! Magnetic fields can be detected with high sensitivity.

[Embodiment] A first embodiment of the present invention will be described based on FIGS. 1 to 3. As shown in Fig. 1, this insulation monitoring antenna device is generated by a partial discharge inside an electrical device such as a gas-insulated switchgear in which a live part 5 is surrounded by a grounded metal conduit container 1.2. A slit antenna 4 for detecting high frequency electromagnetic fields is arranged outside the conduit vessel 1.2.

The conduit vessels 1 and 2 are fastened together by screws or the like, with an insulator 3 sandwiched between flanges la and 2a at the ends.

In FIG. 1, the slit antenna 4 is in a state where the circumferential direction of the insulator 3 and the longitudinal direction of the slit 4a are aligned near the insulator 3 such as an insulating ring interposed at the joint of the conduit container 1.2. It is placed in Specifically, the slit antenna 4
is wound around the outer peripheral surfaces of the insulator 3 and the flanges la and 2a, which are sandwiched and fixed between the flanges 1a2a, and is fixedly attached in an insulating state. The outer conductor and center conductor of the coaxial cable 6 are connected to central positions 4b and 4c of the long sides of the cable 4a, respectively.

The slit antenna 4 is made of a Fji copper plate, for example, and is formed by inserting a rectangular slit 4a in the center of the thin copper plate, as shown in FIG. The slit width W should roughly match the thickness d of the insulator 3, and the overall width W of the slit antenna 4 should be larger. , the total width of the insulator 3 and the flange 1b). Further, the length l of the slit 4a is determined from the wavelength λ of the high frequency iam field to be detected, and is approximately λ/2 as a guide. There are no particular regulations regarding the length of the slit antenna 4.

The surface of the slit antenna 4 may be plated with silver plating or the like. In addition, the slit antenna 4
0 surface is provided with an insulating layer (not shown) such as a synthetic resin layer capable of maintaining appropriate insulation strength for insulation from the conduit container 1.2.

In such an insulation monitoring antenna device, a high frequency i! The electromagnetic field is detected from outside the conduit containers 1, 2 by a slit antenna 4, and the degree of insulation deterioration within the conduit container 1.2 is detected based on the high frequency signal obtained from the slit antenna 4. In this case, the conduit vessel 1.2
The antenna 4 detects leakage of the high-frequency electromagnetic field from the insulator 3.

Specifically, when partial discharge occurs within the conduit vessel 1.2 due to insulation deterioration, a high frequency electromagnetic field is generated within the conduit vessel 1.2. This high frequency electromagnetic field is applied to the conduit vessel 1.
It will leak from the part of the insulator 3 that is interposed at the joint between the two. In this case, the leaking high-frequency electromagnetic field is transmitted through the insulator 3
This is induced by the potential difference that occurs between the two conduit vessels 1 and 2 that sandwich the insulator 3 due to impedance mismatch, and the direction of the electric field E outside the insulator 3 is perpendicular to the circumferential direction of the insulator 3. do.

On the other hand, the slit antenna 4 has high detection sensitivity for electric fields in a direction perpendicular to the longitudinal direction of the slit 4a, and when the longitudinal direction of the slit 4a of the slit antenna 4 is aligned with the circumferential direction of the insulator 3, If placed nearby, the high-frequency electromagnetic field leaking from the insulator 3 can be received at a high level, and the high-frequency electromagnetic field leaking from the insulator 3 can be received at a high level. Since the direction of the electromagnetic field matches the direction orthogonal to the longitudinal direction of the slit of the slit antenna 4, which has high detection sensitivity for high-frequency electromagnetic fields, the slit antenna can detect high-frequency electromagnetic fields leaking from the insulator 3 with high sensitivity. 4 can detect the high-frequency electromagnetic field leaking from the insulator 3 with high sensitivity because the direction of the magnetic field H of the slit antenna 4 where the length l of the slit 4a is λ/2 is This is because the direction of the electric field E is parallel to the longitudinal direction of the slit 4a, and the direction of the electric field E is perpendicular to the longitudinal direction of the slit 4a.
Figure (dipole antenna 57 with a length of λ/2 shown in bl)
is in a complementary relationship with the electric field E of the dipole antenna 57.
The direction of the magnetic field H is parallel to the longitudinal direction of the element, and the direction of the magnetic field H is perpendicular to the longitudinal direction of the element.

The insulation monitoring antenna device of this embodiment uses a slit antenna 4 to detect a high-frequency ill field due to partial discharge inside the conduit container 1.2, so the slit antenna 4 is placed along the insulator 3. It is easy to bring them close together, and the direction of the detected electric field of the slit antenna 4 can be matched with the direction of the high frequency electric field leaking through the insulator 3.
A high-frequency electromagnetic field generated by partial discharge inside the conduit vessels 1.2 when the insulation deteriorates can be detected with high sensitivity from outside the conduit vessels 1.2.

A second embodiment of the invention will be described based on FIG. 4.

This insulation monitoring antenna device includes a slit antenna 4'
is constructed using insulated wires such as vinyl coated wires instead of punched conductive plates, and the other constructions are the same as the first one.
This is similar to the embodiment shown in the figure.

This embodiment has the advantage that the slit antenna 4' can be easily manufactured. Other functions and effects are similar to those of the embodiment shown in FIG.

A third embodiment of the invention will be described based on FIGS. 5 and 6. This insulation monitoring antenna device has a balun circuit 8 for balanced/unbalanced conversion inserted between the slit antenna 4 and the coaxial cable 6, and the rest is the embodiment shown in FIG. 1 or the embodiment shown in FIG. 4. This is similar to the embodiment.

As an example of the balun circuit 8, the one shown in FIGS. 6(al) and (b) can be considered.

The reason why the balun circuit 8 is inserted in this way is as follows. That is, unlike a parallel feeder, the coaxial cable 6 is an unbalanced transmission path, so a part of the signal from the slit antenna 4 may leak into the outer sheath of the coaxial cable 6, or a noise current in the outer sheath of the coaxial cable 6 may pass through the slit. antenna 4
to invade.

To prevent such problems, it is necessary to perform balanced/unbalanced conversion.

A fourth embodiment of the invention will be described based on FIG. 7.

This insulated-celebration antenna device is, as shown in Fig. 7,
The slit antenna 4 is connected to the insulator 3 and the flanges la, 2
The entire area around the joint of the conduit container 12, including portion a, is covered with a conductive electromagnetic shielding material 9A. In this case, the slit antenna 4 is
The insulating resin 9B protects the insulator 3 and the flange 1a2.
A shield material 9A is provided on the outside of the insulating resin 9B.

The shield material 9A may simply be brought into close contact with the periphery of the joint between the conduit containers 1 and 2;

An insulating paint 10 is usually applied to the outer surface of the shield member 2, and the shield material 9A is only electrostatically coupled to the conduit vessels 1 and 2 as it is. Therefore, in this example, a part of the insulating paint 1O is peeled off and a conductive paint (not shown) is applied to that part.
It is preferable to coat the shield +49A with the conduit vessel 1.2 to establish a direct electrical connection between the shield +49A and the conduit vessel 1.2.

By providing the shield material 9A in this way, unnecessary external electromagnetic waves can be shielded, and the S/N ratio of discharge detection can be improved. Other effects are similar to those of the first embodiment.

In each of the above embodiments, the slit antenna 44' is
Although the configuration in which only two slits are provided is shown, two slits with different lengths are provided.
More than one slit antenna may be wound around the insulator 3.

Further, in the above embodiment, the insulator 3 is used as the conduit container 1.
The example is an insulating spacer that insulates between two parts, but it is not limited to this, but can be applied to any joint of a container where there is a gasket or an insulating layer is formed by a painted surface, and where there is a possibility that high-frequency signals may leak. , it is possible to apply this invention.

A fifth embodiment of the invention will be described based on FIGS. 8 and 9. In this insulation monitoring antenna device, a slit antenna 4'' curved in a substantially C shape is placed in a metal container 11.
For example, it is fixed to the outer surface of the container 11 in such a manner that it surrounds an insulator portion of a drawer bushing 12 protruding from the container 11 .

13 is a coaxial cable.

In this embodiment as well, the high frequency electromagnetic field leaking from the insulator portion of the bushing 12 can be detected in the same manner as in the embodiments described above, and partial discharge due to insulation deterioration within the container 11 can be detected.

〔Effect of the invention〕

According to the insulation monitoring antenna device of the present invention, the slit antenna is used to detect the high frequency electromagnetic field due to partial discharge inside the container, so it is easy to place the slit antenna close to the insulator. Moreover, the direction of the detected electric field of the slit antenna and the direction of the high-frequency electric field leaking through the insulator can be matched, and the high-frequency electromagnetic field generated by partial discharge inside the container when the insulation deteriorates can be detected with high sensitivity from outside the container. I can do it.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an insulation monitoring antenna device according to a first embodiment of the present invention, FIG. 2 is a plan view of the slit antenna shown in FIG. 1, and FIG. 3 is a complement of the slit antenna and dipole antenna. FIG. 4 is a perspective view of the insulation monitoring antenna device according to the second embodiment of the present invention, and FIG.
The figure is a perspective view of essential parts of an insulation monitoring antenna device according to a third embodiment of the present invention, and FIG. 6 is a circuit diagram showing an example of a balun circuit.
7 is a sectional view of an insulation monitoring antenna device according to a fourth embodiment of the present invention, FIG. 8 is a perspective view of an insulation monitoring antenna device according to a fifth embodiment of the present invention, and FIG. FIG. 10 is a perspective view of a conventional example of an insulation monitoring antenna device, and FIG. 11 is a perspective view of another conventional example of an insulation monitoring antenna device. 1.2... Conduit container, 3... Insulator, 4... Three/t antenna, 4a... Slit Figure 4 (a) (b) Figure 0 Figure 6 Figure 1 Figure 3 7

Claims (1)

[Scope of Claims] An insulation monitoring antenna device that detects a high-frequency electromagnetic field generated by partial discharge inside an electrical device whose live part is surrounded by a grounded metal container from the outside of the container, A slit antenna is arranged near an insulator existing at a joint between the containers or a joint between the container and the bushing, with the circumferential direction of the insulator aligned with the longitudinal direction of the slit. Antenna device for insulation monitoring.