JPH0536377U - Optical voltage / current sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] To use a Pockels element having a Faraday effect in the voltage detection unit so that voltage detection can be performed without being affected by the magnetic field applied to the current detection unit. A voltage detector that converts light linearly polarized by a polarizer 24 into circularly polarized light by a quarter-wave plate 25, enters a Pockels element 26 having a Faraday effect to which a voltage to be measured is applied, and detects the voltage. 20 and a current detector 21 for detecting the current by making the light linearly polarized by the polarizer 31 incident on the Faraday element 33 arranged in the magnetic field H due to the current to be measured, and the both detectors 20 and 21 are Pockels. The optical axis direction of the element 26 and the optical axis direction of the Faraday element 33 are arranged so as to be orthogonal to each other.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical voltage / current sensor that detects voltage and current of a distribution line using a Pockels element and a Faraday element.

[0002]

[Prior Art]

 Conventionally, in the case of optically detecting the voltage and current of a distribution line, as shown in FIG. 3, an optical voltage detection unit 2 and an optical current detection unit 3 are housed in a case 1 and the optical voltage detection unit 2 and the optical current detection unit 3 are accommodated in a case to be measured. It is arranged close to the distribution line 4. 5 and 6 are optical fiber cables. The voltage detection unit 2 is configured as shown in FIG. 4, and the case 7 is connected to the optical fiber cable 5 and collimators 8A and 8B on the light incident side and the light emitting side, and a polarizer (PBS) 9 are connected. , 1/4 wave plate 10, Pockels element 11 and analyzer (PBS) 12 are accommodated, and the voltage of the distribution line 4 is appropriately divided and applied to the Pockels element 11.

Then, when light from a light emitting element (not shown) such as a semiconductor laser is incident on the collimator 8A through the optical fiber cable 5, the light entering the collimator 8A is parallel light (light having randomly polarized light). And then reflected by the polarizer 9, whereupon it is linearly polarized by the polarizer 9. The light linearly polarized by the polarizer 9 is converted into circularly polarized light by the quarter-wave plate 10 and passes through the Pockels element 11 in this state. A voltage proportional to the voltage of the distribution line 4 is applied to the Pockels element 11, and the polarization state of the light passing therethrough changes according to the electric field strength applied to the Pockels element 11, and is converted into elliptically polarized light.

Further, the light emitted from the Pockels element 11 is reflected by the analyzer 12, and at this time, the change in the polarization state by the Pockels element 11 is converted into light intensity, which is made incident on the collimator 8B, and the optical fiber cable 5 The light intensity is detected by an optical sensor (not shown) through. Therefore, in the voltage detecting unit 2, when the voltage applied to the Pockels element 11 changes, the polarization state of the transmitted light passing through the Pockels element 11 changes, and the light intensity converted by the analyzer 12 also changes. Therefore, the level of the output signal of the optical sensor changes according to the change of the applied voltage, and the voltage can be detected.

Further, the current detector 3 is configured as shown in FIG. 5, and the case 13 is connected to the optical fiber cable 6 and collimators 14 A and 14 B on the light incident side and the light emitting side, and a triangular prism 15 are provided. , A polarizer (PBS) 16, a Faraday element 17, an analyzer (rotated by 45 degrees about the optical axis with respect to the polarizer 16) 18 and a triangular prism 19, and a magnetic field generated by a current flowing through the distribution line 4. The direction of H is set to be the optical axis direction of the Faraday element 17.

When light from a light emitting element (not shown) such as a semiconductor laser is incident on the collimator 14A through the optical fiber cable 6, the light entering the collimator 14A is collimated light (light having randomly polarized light). After being converted into, the light is totally reflected by the triangular prism 15, further transmitted through the polarizer 16, and is linearly polarized at this time. The light emitted from the polarizer 16 passes through the Faraday element 17 in a linearly polarized state, and the polarization state of the transmitted light changes according to the magnetic field strength applied to the Faraday element 17, that is, the plane of polarization rotates. ..

Further, the light emitted from the Faraday element 17 passes through the analyzer 18, and at this time, the rotation of the polarization plane by the Faraday element 17 is converted into light intensity, and the light emitted from the analyzer 18 is converted into a triangular prism. The light is totally reflected by 19 and is incident on the collimator 14B, and the light intensity is detected by an optical sensor (not shown) through the optical fiber cable 6. Therefore, in the current detecting unit 3, when the current flowing through the distribution line 4 changes, the magnetic field strength applied to the Faraday element 17 changes, and the polarization state of the transmitted light of the Faraday element 17 changes, which is detected by the analyzer 18. The intensity of the emitted light also changes, so that the level of the output signal of the optical sensor changes according to the change in the current flowing through the distribution line 4, and the current can be detected.

[0008]

[Problems to be solved by the device]

 By the way, when the Pockels element 11 which does not have the Faraday effect is used as the Pockels element 11 in the voltage detection unit 2 described above, the voltage detection unit 2 is placed close to the current detection unit 3 as shown in FIG. There is no effect even if it is placed in the magnetic field H due to the current flowing through No. 4, but in this case, in order to eliminate the effect of the electric field due to pyroelectricity, all six surfaces of the Pockels element have electrodes (light entrance and exit surfaces are It is necessary to form a transparent electrode), which has a drawback that it takes time to process the electrode.

On the other hand, in the case of a Pockels element having a Faraday effect such as BSO or BGO, it can be obtained at low cost, and it can be used for detection of both voltage and current, and the electrode treatment as described above can be performed. It is not necessary, and voltage detection can be performed by forming transparent electrodes on the incident surface and the emission surface of light orthogonal to the optical axis and applying a voltage between them, that is, in the optical axis direction.

However, in the structure shown in the conventional example, when the Pockels element having the Faraday effect is used for the voltage detection unit 2, the magnetic field H due to the current acts in the optical axis direction, so that the influence of the magnetic field H is reduced. Then, the Faraday effect causes a polarization state, which causes a problem that accurate voltage detection cannot be performed.

The present invention has been made in view of such problems of the conventional technique, and the purpose thereof is to use a Pockels element having a Faraday effect in the voltage detection unit to generate a magnetic field. An object is to provide an optical voltage / current sensor that can detect voltage without being affected.

[0012]

[Means for Solving the Problems]

 In order to achieve the above object, in the optical voltage-current sensor of the present invention, light linearly polarized by a polarizer is converted into circularly polarized light and incident on a Pockels element having a Faraday effect to which a voltage to be measured is applied. The Pockels element's optical axis and the voltage detection section that detects the voltage and the current detection section that detects the current by injecting the light linearly polarized by the polarizer into the Faraday element that is placed in the magnetic field due to the current to be measured. And the direction of the optical axis of the Faraday element are orthogonal to each other.

[0013]

[Action]

 In the optical voltage / current sensor with the above-mentioned configuration, the current detector is installed in the magnetic field due to the measured current so that the optical axis direction of the Faraday element and the magnetic field direction due to the current match. For the Pockels element whose direction is orthogonal to that of the Faraday element, the magnetic field acts in the direction orthogonal to the optical axis, and the Pockels element having the Faraday effect can ignore the influence of the magnetic field. ..

[0014]

【Example】

 An example will be described with reference to FIGS. 1 and 2. Example 1 First, Example 1 will be described with reference to FIG. As shown in the figure, the voltage detection unit 20 that optically detects the voltage of the distribution line and the current detection unit 21 that optically detects the current flowing through the distribution line are placed close to the distribution line to be measured. There is.

The voltage detection unit 20 includes a case 22 having light incident side and light emitting side collimators 23 A, 23 B, a polarizer 24, a quarter-wave plate 25, a Pockels element 26 having a Faraday effect, an analyzer 27, and a triangle. A voltage obtained by appropriately dividing the voltage of the distribution line is applied between the transparent electrodes formed on the light incident surface and the light emitting surface of the Pockels element 26, which are configured to accommodate the prism 28.

Further, the current detector 21 houses the light incident side and light emitting side collimators 30 A and 30 B, the polarizer 31, the half-wave plate 32, the Faraday element 33 and the analyzer 34 in the case 29. The magnetic field H due to the current flowing through the distribution line is oriented in the optical axis direction of the Faraday element 33.

Here, the direction of the optical axis of the Pockels element 26 in the voltage detection unit 20 is set to be orthogonal to the direction of the optical axis of the Faraday element 33 in the current detection unit 21, and therefore the magnetic field H The direction is perpendicular to the optical axis of the Pockels element 26. The Faraday element 33 receives the magnetic field due to the current flowing through the distribution line. For example, the case 29 may be inserted and arranged in the portion where the magnetic path of the C-shaped core surrounding the distribution line is open. Can be considered.

Further, the half-wave plate 32 for optical bias is interposed between the polarizer 31 and the Faraday element 33 because the linearly polarized light is tilted in advance by 45 degrees so that the analyzer 34 can be moved along the optical axis. Since it is not necessary to rotate it by 45 degrees and attach it, the assembly work is improved.

In such a configuration, when the light from the optical fiber cable is incident on the collimator 23A of the voltage detection unit 20, it becomes parallel light by the collimator 23A and is then linearly polarized by the polarizer 24. Further, it is converted into circularly polarized light by the quarter-wave plate 25 and passes through the Pockels element 26. At this time, the polarization state of the light passing therethrough changes in accordance with the electric field strength applied to the Pockels element 26, and is converted into elliptically polarized light. Then, in the analyzer 27, the change in the polarization state is converted into light intensity, and the triangular prism is used. The light is totally reflected at 28 and is incident on the optical fiber cable by the collimator 23B, and the light intensity is detected by an optical sensor (not shown).

On the other hand, when the light from the optical fiber cable is incident on the collimator 30A of the current detector 21, the collimator 30A forms parallel light, which is then linearly polarized by the polarizer 31 and further ½ wavelength plate. At 32, the plane of polarization is rotated by 45 degrees and passes through the Faraday element 33. At this time, the polarization plane of the light passing therethrough is rotated according to the magnetic field strength of the magnetic field H applied to the Faraday element 33, and the rotation of this polarization plane is converted into the light strength by the analyzer 34, and the collimator 30B converts it into an optical fiber cable. The light is incident and the light intensity is detected by an optical sensor (not shown).

By the way, the voltage detection unit 20 and the current detection unit 21 are arranged close to each other, and the magnetic field H applied to the Faraday element 33 of the current detection unit 21 also acts on the Pockels element 26 of the voltage detection unit 20. However, in this case, since the direction of the optical axis of the Pockels element 26 and the direction of the optical axis of the Faraday element 33 are orthogonal to each other and the magnetic field H acts on the Pockels element 26 in the direction orthogonal to the optical axis, the Faraday effect is produced. In the Pockels element 26 that it has, it becomes possible to ignore the influence of the magnetic field H.

Second Embodiment Next, a second embodiment will be described with reference to FIG. In the figure, the difference from the above is that the voltage detection unit 20 and the current detection unit 21 are housed in one case 35 and the two are integrated, and the light from the optical fiber cable is collimated on the light incident side. 36A converts the light into parallel light, and the polarizer 37 separates the light into two linearly polarized lights of P-polarized light and S-polarized light. P-polarized light is used for the voltage detection unit 20 and S-polarized light is used for the current detection unit 21. It is the one. Reference numerals 36B and 36C are collimators on the light emitting side.

In this case, since the optical axis of the Pockels element 26 and the optical axis of the Faraday element 33 are orthogonal to each other, the optical axis of the Pockels element 26 is affected by the magnetic field H applied to the Faraday element 33 in the optical axis direction. Are orthogonal to each other, and in the Pockels element 26 having the Faraday effect, the influence of the magnetic field H can be ignored.

In particular, in the case of this embodiment, since the two detectors 20 and 21 are integrated and housed in one case 35, one optical fiber cable, collimator, polarizer and the like can be reduced, and voltage and current can be reduced. The overall size of the sensor has been reduced, which is also extremely advantageous in terms of installation space.

[0025]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it has the following effects. Since the voltage detection section using the Pockels element having the Faraday effect and the current detection section using the Faraday element are arranged so that the optical axes of both elements are orthogonal to each other, the voltage is applied in the optical axis direction of the Faraday element. The magnetic field generated by the Pockels element is orthogonal to the optical axis of the Pockels element, and the influence of the magnetic field can be ignored in the Pockels element. The voltage and current detection accuracy is improved, and the Pockels element, which has the Faraday effect, is used. Electrode treatment is reduced, and the cost is reduced.

[Brief description of drawings]

FIG. 1 is a first embodiment of an optical voltage / current sensor according to the present invention.
It is a schematic block diagram which shows.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the present invention.

3A and 3B show how the sensor is attached to a distribution line, FIG. 3A being a front view and FIG. 3B being a side view.

FIG. 4 is a schematic configuration diagram showing a voltage detection unit of a conventional example.

FIG. 5 is a schematic configuration diagram showing a conventional current detection unit.

[Explanation of symbols]

 20 Voltage Detector 21 Current Detector 24, 31, 37 Polarizer 25 1/4 Wave Plate 26 Pockels Element 27, 34 Analyzer 32 1/2 Wave Plate 33 Faraday Element

Claims (1)

[Scope of utility model registration request] 1. A voltage detection unit for converting linearly polarized light by a polarizer into circularly polarized light and making it incident on a Pockels element having a Faraday effect to which a voltage to be measured is applied and detecting the voltage.
A linearly polarized light with a polarizer is provided to a Faraday element arranged in a magnetic field due to the current to be measured, and a current detecting section for detecting a current is provided, and the both detecting sections are arranged in the direction of the optical axis of the Pockels element and An optical voltage / current sensor which is arranged so as to be orthogonal to the optical axis direction of the Faraday element.