JPH0734604B2 - Insulation monitoring antenna device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an internal part of an electric device such as a gas-insulated switchgear that surrounds a charging part with a grounded metal container when insulation deteriorates. The present invention relates to an insulation monitoring antenna device for detecting a discharge (corona discharge).

[Conventional technology]

For example, as shown in FIG. 10, a conventional insulation monitoring antenna device attached to a gas-insulated switchgear has an insulation ring or the like interposed between the grounded metal conduit containers 51 and 52. A loop antenna 54 is arranged near the body 53.

The conduit containers 51, 52 are made of an insulating material between the flanges 51a, 52a at the ends.
Both are clamped and fixed by sandwiching 53 with screws or the like.The loop antenna 54 is shown in Fig. 10 as a flange.
In the vicinity of 51a, the pipe container 51 is installed in an insulated state and wound around the pipe container 51.

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

In such an insulation monitoring antenna device, the high frequency electromagnetic field generated by the partial discharge accompanying the insulation deterioration of the conduit containers 51, 52 is fed from the outside of the conduit containers 51, 52 by the loop antenna 5
The degree of insulation deterioration inside the conduit vessels 51, 52 is detected based on the high frequency signal detected by the loop antenna 54. In this case, the loop antenna 54 detects that the high-frequency electromagnetic field in the conduit containers 51, 52 leaks from the insulator 53.

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

In such an insulation monitoring antenna device, since the dipole antenna 57 is arranged in the portion of the insulator 53 where the high-frequency electromagnetic field leaks, the high-frequency electromagnetic field leaking from the conduit containers 51, 52 has the highest level. Can be received at.

[Problems to be Solved by the Invention]

In the insulation monitoring antenna device of FIG. 10, the high frequency leakage current caused by the partial discharge is detected by the loop antenna 54 wound around the flange 51a of the one conduit container 51, and the insulator 53 to the loop antenna 54 are detected. Since they are far apart, the detection sensitivity was low.

In addition, in the insulation monitoring antenna device of FIG.
The high-frequency electromagnetic field leaking from the portion of the insulator 53 is generated by partial discharge in the conduit vessels 51, 52, resulting in a potential difference due to impedance mismatch between the flanges 51a, 52a. Since a high frequency electromagnetic field is generated in the electric field, the direction of the electric field E in the high frequency electromagnetic field is the thickness direction of the insulator 53, that is, the longitudinal direction of the conduit containers 51, 52. On the other hand, the direction of the electric field detectable by the dipole antenna 57 is the longitudinal direction of the element, that is, the direction orthogonal to the thickness direction of the insulator 53. Therefore, the dipole antenna 57 could hardly detect the high-frequency electromagnetic field leaking from the insulator 53, and the detection sensitivity was extremely low.

Therefore, an object of the present invention is to provide an insulation monitoring antenna device capable of highly sensitively detecting a high-frequency electromagnetic field generated by partial discharge inside the container during insulation deterioration from the outside of the container.

[Means for Solving the Problems]

The insulation monitoring antenna device of the present invention detects the high frequency electromagnetic field generated by the partial discharge inside the electric device in which the charging part is surrounded by the grounded metal container from the outside of the container by the slit antenna. ing. The slit antenna is arranged in the vicinity of the insulator existing at the joint between the containers or the joint between the container and the bushing in a state where the circumferential direction of the insulator and the slit longitudinal direction are aligned.

[Operation] According to the configuration of the present invention, when partial discharge occurs due to insulation deterioration in the container, a high-frequency electromagnetic field is generated in the container. This high-frequency electromagnetic field will leak from the portion of the insulator existing 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 both containers sandwiching the insulator or between the container and the bushing, and the direction of the electric field is orthogonal to the circumferential direction of the insulator.

On the other hand, the slit antenna has a high detection sensitivity of an electric field in a direction orthogonal to the longitudinal direction of the slit, and when the slit antenna is placed in the vicinity of the insulator in the state where the longitudinal direction of the slit is aligned with the circumferential direction of the insulator, insulation is increased. The high-frequency electromagnetic field leaking from the body can be received at a high level, and the direction of the electric field of the high-frequency electromagnetic field leaking from the insulator matches the direction orthogonal to the longitudinal direction of the slit of the slit antenna with high detection sensitivity of the high-frequency electromagnetic field. Therefore, the high frequency electromagnetic field leaking from the insulator can be detected with high sensitivity.

〔Example〕

A first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, this insulation monitoring antenna device is generated by partial discharge inside an electric device such as a gas-insulated switchgear in which a charging part 5 is surrounded by grounded metal conduit containers 1 and 2. A slit antenna 4 for detecting the generated high-frequency electromagnetic field is arranged outside the conduit containers 1 and 2.

The conduit containers 1 and 2 are clamped and fixed by sandwiching the insulator 3 between the flanges 1a and 2a at the ends and screwing them together.

In FIG. 1, the slit antenna 4 is in a state in which the circumferential direction of the insulator 3 and the longitudinal direction of the slit 4a are aligned in the vicinity of the insulator 3 such as an insulating ring interposed in the joint between the pipe containers 1 and 2. It is arranged in. Specifically, the slit antenna 4 is
The insulator 3 sandwiched and fixed by the flanges 1a and 2a and the outer peripheral surfaces of the flanges 1a and 2a are wrapped and fixed in an insulated state. The outer conductor and the center conductor of the coaxial cable 6 are connected to the central positions 4b and 4c of the long sides of the slit 4a, respectively.

The slit antenna 4 is made of, for example, a thin copper plate,
As shown in FIG. 2, it is formed by inserting a rectangular slit 4a in the central portion of a thin copper plate. It is preferable that the slit width w is approximately matched with the thickness d of the insulator 3 and the overall width W of the slit antenna 4 is large. However, for example, due to the restrictions of the arrangement location, for example, the connecting portions of the conduit containers 1 and 2 (flange 1a, It is set to be slightly wider than the total width of the insulator 3 and the flange 1b). The length 1 of the slit 4a is determined from the wavelength λ of the high frequency electromagnetic field to be detected, and about λ / 2 is a standard. The length L of the slit antenna 4 is not specified.

The surface of the slit antenna 4 may be plated with silver, for example. In addition, the slit antenna 4
An insulating layer (not shown) such as a synthetic resin layer capable of maintaining an appropriate insulating strength is provided on the surface of the in order to insulate the conduit containers 1 and 2.

In such an insulation monitoring antenna device, the high frequency electromagnetic field generated by the partial discharge associated with the insulation deterioration of the conduit containers 1 and 2 is applied to the slit antenna 4 from outside the conduit containers 1 and 2.
And the degree of insulation deterioration in the conduit containers 1 and 2 is detected based on the high frequency signal obtained from the slit antenna 4. In this case, the slit antenna 4 detects that the high-frequency electromagnetic field in the conduit containers 1 and 2 leaks from the insulator 3.

Specifically, when a partial discharge occurs in the conduit containers 1 and 2 due to insulation deterioration, a high frequency electromagnetic field is generated in the conduit containers 1 and 2. This high-frequency electromagnetic field will leak from the portion of the insulator 3 which is interposed at the joint between the conduit containers 1 and 2. In this case, the leaking high-frequency electromagnetic field is induced by the potential difference generated between the two conduit vessels 1 and 2 that sandwich the insulator 3 due to the impedance mismatch due to the insulator 3.
The direction of the electric field E outside the insulator 3 is orthogonal to the circumferential direction of the insulator 3.

On the other hand, the slit antenna 4 has a high detection sensitivity of the electric field in the direction orthogonal to the longitudinal direction of the slit 4a, and the slit antenna 4 of the slit antenna 4 is aligned with the circumferential direction of the insulator 3 in a state where the longitudinal direction of the slit 4a is aligned with the circumferential direction of the insulator 3. If it is placed in the vicinity, the high frequency electromagnetic field leaking from the insulator 3 can be received at a high level
Moreover, since the direction of the electric field of the high frequency electromagnetic field leaking from the insulator 3 and the direction orthogonal to the slit longitudinal direction of the slit antenna 4 having a high detection sensitivity of the high frequency electromagnetic field coincide with each other, the high frequency electromagnetic field leaking from the insulator 3 is highly sensitive. Can be detected with.

The high frequency electromagnetic field leaking from the insulator 3 can be detected with high sensitivity by the slit antenna 4 as shown in FIG. 3 (a) because the magnetic field H of the slit antenna 4 in which the length l of the slit 4a is λ / 2. This is because the direction of is parallel to the longitudinal direction of the slit 4a, and the direction of the electric field E is orthogonal to the longitudinal direction of the slit 4a. Such a slit antenna 4 has a complementary relationship with the dipole antenna 57 having a length of λ / 2 shown in FIG. 3B, and the direction of the electric field E of the dipole antenna 57 is parallel to the longitudinal direction of the element. Therefore, the direction of the magnetic field H is orthogonal to the longitudinal direction of the element.

Since the insulation monitoring antenna device of this embodiment is configured to detect the high frequency electromagnetic field due to the partial discharge in the conduit vessels 1 and 2 by using the slit antenna 4, the slit antenna 4 is used.
Can be easily brought close to each other along the insulator 3, and the direction of the detected electric field of the slit antenna 4 and the direction of the high-frequency electric field leaking through the insulator 3 can be matched. The high-frequency electromagnetic field generated by the partial discharge inside the container can be detected from the outside of the conduit vessels 1 and 2 with high sensitivity.

A second embodiment of the present invention will be described with reference to FIG.
This insulation monitoring antenna device includes a slit antenna 4 '.
Is configured by using an insulation-coated electric wire such as a vinyl-coated electric wire instead of punching a conductive plate.
This is similar to the embodiment shown in the figure.

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

A third embodiment of the present invention will be described with reference to FIGS. 5 and 6. This insulation monitoring antenna device is one in which a balun circuit 8 for balanced / unbalanced conversion is inserted between a slit antenna 4 and a coaxial cable 6, and the others are the same as the embodiment of FIG. 1 or FIG. It is similar to the embodiment of.

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

The reason for inserting the balun circuit 8 in this way is as follows. That is, unlike the parallel feeder, the coaxial cable 6 is an unbalanced transmission line, and therefore, a part of the signal of the slit antenna 4 leaks to the jacket of the coaxial cable 6 or the noise current of the jacket of the coaxial cable 6 is slit. Antenna 4
Break into. To prevent such a problem, balanced / unbalanced conversion must be performed.

A fourth embodiment of the present invention will be described with reference to FIG.
This insulation monitoring antenna device, as shown in FIG.
The slit antenna 4, including the insulator 3 and the flanges 1a and 2a, is covered with a shield material 9A for electromagnetic shielding, which has conductivity as a whole, around the joints of the conduit vessels 1 and 2. . In this case, the slit antenna 4 is fixed to the slit 3 around the insulator 3 and the flanges 1a and 2a by the insulating resin 9B, and the shield material 9A is provided outside the insulating resin 9B.

The shield material 9A may be simply brought into close contact with the periphery of the joints of the pipeline containers 1 and 2, but the outer surface of the pipeline containers 1 and 2 is usually coated with the insulating coating material 10 and the shield material 9A as it is.
Is only electrostatically coupled to the conduit containers 1 and 2. For this reason, in this embodiment, a part of the insulating paint 10 is peeled and removed, and a conductive paint (not shown) is applied to the part, so that the shield material 9A and the conduit containers 1 and 2 are directly connected to each other. It is preferable to make an electrical connection.

Thus, by providing the shield material 9A, 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 antennas 4 and 4'are
Only the number of slits is shown, but 2 with different slit lengths
You may make it wind around the insulator 3 with one or more slit antennas.

Further, in the above-mentioned embodiment, as the insulator 3, the conduit containers 1, 2
Although the insulating spacer that insulates between is taken as an example, the present invention is not limited to this. For example, a gasket may be interposed, or an insulating layer may be formed by a painted surface, so that there is a possibility that a high-frequency signal may leak at any joint part of the container, This invention can be applied.

A fifth embodiment of the present invention will be described with reference to FIGS. 8 and 9. In this insulation monitoring antenna device, a slit antenna 4 ″ curved in a substantially C shape is provided on the outer surface of the container 11 so as to surround the insulator portion of a bushing 12 for pulling out, which is projected on the metal container 11, for example. 13 is a coaxial cable.

Also in this embodiment, the high-frequency electromagnetic field leaking from the insulator portion of the bushing 12 can be detected by the same action as in each of the above embodiments, and the partial discharge due to the insulation deterioration in the container 11 can be detected.

〔The invention's effect〕

According to the insulation monitoring antenna device of the present invention, since the high frequency electromagnetic field due to the partial discharge in the container is detected by using the slit antenna, it is easy to bring the slit antenna close to the insulator. Moreover, the direction of the electric field detected by 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 the partial discharge inside the container during insulation deterioration can be detected with high sensitivity from the outside of the container. You can

[Brief description of drawings]

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 a slit antenna shown in FIG. 1, and FIG. 3 is a complement of a slit antenna and a dipole antenna. 4 is a perspective view of an insulation monitoring antenna device according to a second embodiment of the present invention, and FIG.
FIG. 6 is a perspective view of an essential part 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.
FIG. 7 is a sectional view of an insulation monitoring antenna apparatus according to a fourth embodiment of the present invention, FIG. 8 is a perspective view of an insulation monitoring antenna apparatus according to a fifth embodiment of the present invention, and FIG. FIG. 10 is a plan view of the slit antenna shown in the figure, 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 …… Pipe container, 3 …… Insulator, 4 …… Slit antenna, 4a …… Slit

Claims (1)

[Claims] 1. An insulation monitoring antenna device for detecting, from the outside of the container, a high-frequency electromagnetic field generated by a partial discharge inside an electric device in which a charging part is surrounded by a grounded metal container. Insulation characterized in that a slit antenna is arranged in a state where the circumferential direction of the insulator and the slit longitudinal direction are aligned, in the vicinity of the insulator existing at the joint between the containers or at the joint between the container and the bushing. Monitoring antenna device.