JPS6134469A - Optical current measuring apparatus - Google Patents

Abstract

PURPOSE:To prevent the generation of noises, by supporting a photocurrent sensor with an elastic body. CONSTITUTION:A peripheral integration type photocurrent sensor 1 is incorporated into a metal case 2, which is fastened on a conductor 3 with a fixed fastening metal 4 and suppored as a whole with an insulation support base 6. The sensor 1 is supported with an elastic body, for example, plate spring 7. In this manner, the vibration caused by an electromagnetic force generated in the base 2 and the conductor 3 is absorbed with the plate spring 7 to prevent the generation of noise in the sensor 1.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to an optical current measuring device.

[Background of the invention]

Conventionally, wound type current transformers have been the mainstream as current transformers for power use. However, recently there has been a shift toward digitalization systems to protect and control power system equipment at high speed and with high reliability. It is essential to accurately and safely measure and monitor the current and voltage of each part in the operation of equipment.

For this reason, in recent years, the application of optical current pressure sensors using the electro-optic effect, which has the characteristics of small size, light weight, high performance, non-induction, wide band, and many ohms, has been considered.
3174. JP-A-58-97663° JP-A-55-12
4960. This is disclosed in Japanese Patent Application Laid-Open No. 55-125615.

However, these technologies did not recognize the problem of noise generation due to mechanical vibrations caused by electromagnetic force when large currents flow.

The inventors fixed the disclosed photocurrent sensor to a current conductor to be measured or a supporting member and case supporting the sensor, and measured the current flowing through the conductor. No abnormality was observed in the output waveform of the sensor, but when a large DC current of several hundred amperes or more was passed through the sensor, a vibration noise waveform appeared in the output of the sensor.

This noise is a phenomenon that can lead to malfunctions in power systems that require highly reliable protection and control.

[Purpose of the invention]

The present invention has been made in view of the above points, and it is an object of the present invention to provide an optical current measuring device that makes it possible to prevent noise from occurring in a photocurrent sensor.

[Summary of the invention]

That is, the present invention provides an optical current measuring device that includes a conductor that is housed inside a case and is supported by the case via a support, and a photocurrent sensor that is arranged to surround this conductor. This device is characterized in that the sensor is supported by an elastic body, so that the photocurrent sensor is supported by the elastic body.

The inventors studied how to prevent noise from occurring in the output of the photocurrent sensor. A photocurrent sensor is installed on or near a conductor, but since it is fixed to a support that vibrates due to electromagnetic force or the like, when vibration occurs, the vibration is transmitted to the sensor. This noise was confirmed to be vibration noise due to the so-called photoelastic effect, which causes a phase shift of light in the optical path within the element due to vibration, since the elements used in the sensor are generally made of glass or crystal. Therefore, in order to prevent the generation of vibration noise, it is sufficient to prevent vibrations from being transmitted to the sensor. The electromagnetic force vibration caused by the dog turtle flow when a power system is short-circuited is generally 100H2 or more. Therefore, the frequency is plotted on the horizontal axis, and the vibration transmission rate from the conductor to the sensor is plotted on the vertical axis, as shown in Figure 2, which shows the change in the vibration transmission rate from the conductor to the sensor depending on the frequency. If the natural frequency determined from the mass m of the optical sensor part and the spring constant of the elastic body is set to 100 Hz It was found that this can be prevented. Therefore, in the present invention, the photocurrent sensor is supported by an elastic body.

By doing so, it is possible to provide an optical current measuring device that can prevent noise from occurring in the optical current sensor.

[Embodiments of the Invention] - The present invention will be described below based on illustrated embodiments. An embodiment of the present invention is shown in FIGS. 1(a) and 1(b). This figure shows a state in which an expanded circuit integral type photocurrent sensor 1 is assembled into a metal case 2. As shown in FIG. A conductor 3 around which the sensor 1 is arranged is fixed to a case 2 with a fixing fitting 4, and the case 2 not only prevents electromagnetic or electrostatic induction from the outside to the sensor 1, but also serves as a dustproof cover. I am accomplishing it. The case 2 is made to have the same potential as the conductor 3, and an insulator 5 is provided on one side so that the current i1 to be measured flowing through the conductor 3 is not shunted, thereby blocking the one-turn current 12 flowing through the case 2. In addition, in the same figure, 6 is an insulating support stand that supports the case 2. In this embodiment of the optical current measuring device configured as described above, the photocurrent sensor 1 is supported by an elastic body such as a leaf spring 7. By doing so, the photocurrent sensor 1 is supported by the leaf spring 7, and an optical current measuring device that can prevent the photocurrent sensor 1 from generating noise can be obtained.

That is, the photocurrent sensor 1 was supported by the case 2 via the leaf spring 7. The leaf spring 7, the photocurrent sensor 1, and the case 2 are each fixed at two points. By doing this, the photocurrent sensor 1 is supported by the leaf spring 7, and vibrations caused by electromagnetic force generated in the case 2 and the conductor 3 are absorbed by the leaf spring 7. Noise generation in the photocurrent sensor 1 can be prevented. The effects of this embodiment are shown in FIGS. 3 and 4. FIG. 3 shows a conventional example in which a photocurrent sensor is directly supported on a case, and FIG. 4 shows a case in which a photocurrent sensor is supported on a case via a leaf spring in this embodiment. Then, without passing any current through the conductor or case, we forcibly applied vibration to the case from the outside, and examined changes in the output waveform of the photocurrent sensor over time. As is clear from these figures, in the conventional example (see Fig. 3), when vibrations are applied to the case from the outside, a large amount of noise is generated. In contrast, this example (
(see Fig. 4), the noise is significantly reduced. The reason why this example exhibits excellent characteristics with less noise generation than the conventional example is because the vibration generated in the case is absorbed by the leaf spring 7 and the influence on the photocurrent sensor is reduced. be.

Another embodiment of the present invention is shown in FIGS. 5(a) and 5(b). In this embodiment, the photocurrent sensor 1 is supported on the conductor 3 via a leaf spring 7. That is, the sensor 1 was supported on the conductor 3 via the leaf spring 7 provided in the gap g between the sensor 1 and the conductor 3. In this case as well, the vibrations from the conductor 3 are absorbed by the leaf spring 7, and the same effects as in the above case can be achieved.

FIG. 6 shows yet another embodiment of the invention. In this embodiment, the photocurrent sensor 1 is GIN (gas insulated switchgear)
This is the case when it is incorporated into 8. A shield ring (with the same potential as the conductor 3) is installed outside the sensor 1 using a part of the conductor 3.
7U/J)9 is provided. In addition, in the same figure, 10
is a sheath. In this embodiment, the photocurrent sensor 1 is supported by the shield link 9 via the leaf spring 7. In this case as well, the vibrations of the conductor 3, that is, the shield link 9, are absorbed by the leaf spring 7, and the same effects as in the above case can be achieved.

Still another embodiment of the present invention is shown in FIGS. 7(a) and 7(b). In this embodiment, the photocurrent sensor 1 is incorporated into the GI8B as in the previous case, but the photocurrent sensor 1 is connected to the conductor 3 via the leaf spring 7 placed in the gap g between them. I supported it. Also in this case, the vibration generated in the conductor 3 is absorbed by the leaf spring 7, and the same effect as in the above case can be achieved.

FIG. 8 shows yet another embodiment of the invention. In this example, the photocurrent sensor 1 is installed on the spacer 11 of GI8B, and the spacer 1 of the support made of insulator
1 is provided with an arm 12 made of the same material as this, and this arm 12
The current sensor 1 was supported via a leaf spring 7. In this case as well, the vibrations generated in the spacer 11 and arm 12 that are integral with the dias 10 are absorbed by the leaf spring 7, and the same effects as in the above case can be achieved. 'Although the leaf spring 7 is used as the elastic body in the above embodiments, it is not limited to this, and it goes without saying that elastic rubber or the like can also be used.

Furthermore, although the arm 12 is provided on the spacer 11, a ring may be provided in place of the arm 12.

〔Effect of the invention〕

As described above, according to the present invention, the generation of noise in the photocurrent sensor is prevented, so that it is possible to obtain an optical current measuring device that can prevent the generation of noise in the photocurrent sensor.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) show an embodiment of the optical current measuring device of the present invention, in which (a) is a vertical side view, and (b) is (
Fig. 2 is a characteristic diagram showing the relationship between the vibration transmission rate and frequency from the conductor to the sensor of the optical current measuring device, and Fig. 3 is the conventional optical current measuring device. A characteristic diagram showing the relationship between the output waveform of the photocurrent sensor of the device and time. FIG. 4 is a characteristic diagram showing the relationship between the output waveform of the photocurrent sensor and time of an embodiment of the optical current measuring device of the present invention. , FIGS. 5(a) and 5(b) show other embodiments of the optical current measuring device of the present invention, in which (a) is a longitudinal cross-sectional side view, and (b) is a side view of (a).
FIG. 6 is a longitudinal sectional view of still another embodiment of the optical current measuring device of the present invention, FIG. 7(a)
, (b) show still another embodiment of the optical current measuring device of the present invention, in which (a) is a longitudinal side view, (b) is a cross-sectional view taken along line C-C in (a), and The figure is a longitudinal sectional side view of still another embodiment of the optical current measuring device of the present invention. DESCRIPTION OF SYMBOLS 1... Photocurrent sensor, 2... Case, 3... Conductor, 4... Fixing metal fittings, 5... Insulator, 6... Insulating support base, 7... Plate ( elastic body), 8... gas insulated switchgear, 9... shield ring (flange), 10...
...Sheath, 11...Spacer, 12...Arm.

Claims (1)

[Claims] 1. An optical current measuring device that is housed inside a case and includes a conductor supported by the case via a support, and a photocurrent sensor disposed surrounding the conductor. . An optical current measuring device, characterized in that the photocurrent sensor is supported by an elastic body. 2. The optical current measuring device according to claim 1, wherein the photocurrent sensor is supported by the case via the elastic body. 3. The optical current measuring device according to claim 1, wherein the photocurrent sensor is supported by the conductor via the elastic body. 4. The optical current measuring device according to claim 1, wherein the photocurrent sensor is supported by a flange attached to the conductor via the elastic body.