JPH08304469A - Current sensor - Google Patents

Abstract

PURPOSE: To miniaturize a current sensor capable of detecting both a large current and a small current. CONSTITUTION: This is a current sensor for outputting a detection signal corresponding to a current value from the rotating amount of a linearly polarized light a plane of polarization of which is rotated in accordance with an intensity of a magnetic field generated by a current to be measured. A light of a light- transmitting collimator 25 is separated to two linearly polarized lights. One of the linearly polarized lights is brought to a first propagation route and the other is sent into a second propagation route. A magnetic field generated by the current to be measured is applied to the first propagation route. A magnetic field from a gap 31a of a gapped iron core 31 is impressed to the second propagation route. The rotating amount of the plane of polarization due to the Faraday effect at the first and second propagation routes is detected independently by a first analyzer 27 and a first photodetecting collimator 29, and a second analyzer 28 and a second photodetecting collimator 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current sensor for measuring a current flowing through an electric wire or the like by utilizing the Faraday effect, and more particularly to a current sensor suitable for measuring a large current and a small current.

[0002]

2. Description of the Related Art Conventionally, there are two kinds of current sensors of this kind, one for detecting a large current and the other for detecting a small current. FIG. 3 shows a configuration example of a current sensor for detecting a large current. In the current sensor shown in the figure, the measurement light emitted from the light-transmitting collimator 1 is incident on the polarizer 2 to extract the linearly polarized light component, and the measurement light of the linearly polarized light component is used by the right-angle prism 3 at a desired Faraday angle. It is incident on the element 4. Then, the measurement light passing through the Faraday element 4 is made incident on the analyzer 6 by using the right-angled prism 5 arranged oppositely, and the light transmitted through the analyzer 6 is made incident on the light receiving collimator 7. The components 1 to 7 are attached to the substrate 8 in the arrangement shown in FIG.

The current sensor constructed as described above is installed at a place separated from the electric wire 9 through which the measured current I flows by a predetermined distance. As shown in the figure, by making the direction of the magnetic field H1 generated by the current I to be measured and the propagation direction of the linearly polarized light in the Faraday element 4, the polarization plane of the linearly polarized light rotates in proportion to the strength of the magnetic field H1. To do. The amount of rotation of the polarization plane of the Faraday element 4 appears as the transmittance of the analyzer 6, so the amount of light that has passed through (or reflected) the analyzer 6 and is incident on the light receiving collimator 7 can be detected. I can be obtained.

On the other hand, a current sensor for detecting a small current is shown in FIG.
As shown in, a part of the substrate 8 to which the same constituent elements as the current sensor for large current detection are attached is inserted into the gap portion of the iron core 11 with a gap. still,
The same components as those of the sensor shown in FIG. 3 are designated by the same reference numerals.

The current sensor constructed as described above is arranged so that the electric wire 10 through which the current I to be measured flows is located at the center of the iron core 11. A magnetic field H2 corresponding to the measured current I flowing through the electric wire 10 is generated in the gap of the iron core 11, and the plane of polarization of the linearly polarized light propagating through the Faraday element 4 rotates in proportion to the strength of the magnetic field H2. Therefore, by detecting the amount of light incident on the light receiving collimator 7, the measured current I can be obtained as in the case of the current sensor for detecting a large current described above.

[0006]

However, as described above, the current sensor for detecting a large current and the current sensor for detecting a small current are configured as independent and separate, so that these two types of current sensors are used. If a current sensor that can measure a wide range of current from large current to small current is configured by combining the above, there arises a problem that a large number of parts are overlapped and the sensor becomes large.

Further, since the conventional current sensor does not utilize the reflected light generated when the measuring light is incident on the polarizer as described above for current measurement, a part of the measuring light is wasted. Was there.

The present invention has been made in view of the above circumstances and is applicable to current measurement from a large current to a small current, has a small number of parts, can be easily made compact, and can efficiently measure light. It is an object to provide a current sensor that can be used.

[0009]

The present invention has taken the following means in order to achieve the above object. The present invention corresponding to claim 1 receives linearly polarized light whose polarization plane is rotated according to the strength of a magnetic field generated by the current to be measured, and based on the rotation amount of the polarization plane, the current value of the current to be measured. In a current sensor that outputs a detection signal according to, a light-transmitting collimator that emits light, a polarizing beam splitter that splits the light emitted from the light-transmitting collimator into reflected light and transmitted light, and forms two linearly polarized lights, One of the linearly polarized light beams produced by this polarization beam splitter is incident on and propagates in the magnetic field direction due to the current to be measured, and the polarization plane of the linearly polarized light is rotated according to the strength of the magnetic field. , This first
A first analyzer on which one linearly polarized light emitted from the light propagation path is incident, a first light receiving collimator for receiving the light transmitted through the first analyzer, and the other formed by the polarization beam splitter. Second light propagation path that rotates the polarization plane of the linearly polarized light of which is incident on and propagates in a predetermined direction according to the strength of the magnetic field, and the other straight line of light emitted from the second light propagation path. A second analyzer on which polarized light is incident,
A second light receiving collimator that receives the light that has passed through the second analyzer and an iron core with a gear that sandwiches both ends of the second light propagation path in a gap are provided.

According to a second aspect of the present invention, in the current sensor having the above structure, the first light propagation path and the second light propagation path are formed in one Faraday element. Claim 3
The present invention corresponding to the present invention relates to the light-transmitting collimator, the polarization beam splitter, the first and second light propagation paths, the first and second analyzers, and the first and second light-receiving collimators constituting the current sensor. Were placed on the same substrate surface.

The present invention corresponding to claim 4 is based on the first and second aspects.
Of the light propagation path of Faraday element or zinc selenium (Z
nSe). The present invention corresponding to claim 5 is a gas-sealed storage container in which a conducting wire through which a current to be measured flows is gas-insulated and stored, and a plurality of gas purging valves are attached to the storage container according to any one of claims 1 to 4. The current sensor described was arranged.

[0012]

The present invention has the following effects by taking the above measures. According to the present invention corresponding to claim 1, the light emitted from the light-transmitting collimator enters the polarization beam splitter and becomes two linearly polarized lights. When one linearly polarized light is incident on the first light propagation path and propagates, the polarization plane is rotated by the magnetic field generated by the current to be measured. The linearly polarized light emitted from the first light propagation path passes through the first analyzer and is received by the first light receiving collimator. On the other hand, when the other linearly polarized light enters the second light propagation path and propagates, the magnetic field between the gaps of the iron core with gap is applied to the second light propagation path, and the polarization plane of the linearly polarized light rotates. The linearly polarized light emitted from the second light propagation path passes through the second analyzer and is received by the second light receiving collimator.

According to the present invention corresponding to claim 2,
Since the light propagation path and the second light propagation path are formed in one Faraday element, the entire sensor can be made compact and the number of parts can be reduced.

According to the present invention corresponding to claim 3, since the predetermined components of the current sensor are arranged on the same substrate surface, the entire sensor can be made compact. According to the present invention corresponding to claim 4, since the first and second light propagation paths or the Faraday element are made of zinc selenium (ZnSe), the polarization plane of the linearly polarized light is accurately determined according to the magnitude of the measured current. Can be rotated.

According to the present invention corresponding to claim 5, since the current sensor according to any one of claims 1 to 4 is provided in the gas-sealed container for gas-insulating and housing the conducting wire, the current sensor of the current sensor is provided. The occupied space can be reduced.

[0016]

Embodiments of the present invention will be described below. FIG. 1 shows the configuration of a current sensor according to an embodiment of the present invention. In the current sensor of this embodiment, a Faraday element 22 is provided on one substrate surface 21a of the substrate 21. The Faraday element 22 is made of a rectangular plate material having a predetermined thickness, and has a size capable of applying a magnetic field H1 and a magnetic field H2 having different strengths to different regions in parallel. The Faraday element 22 is composed of zinc selenium (ZnSe).

A polarization beam splitter 23 and a right-angle prism 24 are arranged so as to face one end face of the Faraday element 22. The light-transmitting collimator 25 has its exit end face with respect to the polarization beam splitter 23.
Is arranged so as to face the incident surface of. The polarization beam splitter 23 splits the measurement light incident from the light-transmitting collimator 25 into two linearly polarized light components orthogonal to each other, bends the first linearly polarized light component in the traveling direction by 90 degrees, and forms one of the Faraday elements 22. Incident on the end face, and the second
Has a plane of polarization for transmitting the linearly polarized light component of (4) to the right-angle prism 24 side. The right-angled prism 24 is arranged so that the second linearly polarized light component incident from the polarization beam splitter 23 is bent by 90 degrees in its traveling direction and is incident on one end face of the Faraday element 22.

On the other hand, a right-angle prism 26 and a large current detection side analyzer (hereinafter referred to as "first analyzer") 27 are provided facing the other end surface of the Faraday element 22.
The right-angle prism 26 bends the second linearly polarized light component emitted from the Faraday element 22 by 90 degrees in its traveling direction, and an analyzer on the small current detection side (hereinafter, referred to as “second analyzer”) 2
8 is arranged so as to enter. First analyzer 27
Is a position distant from the other end surface of the Faraday element 22 to a position where it does not interfere with the optical path between the right-angled prism 26 and the second analyzer 28, and the first linearly polarized light component emitted from the Faraday element 22 can enter. It is located in a position. First
The light receiving collimator on the large current detection side (hereinafter, referred to as “first light receiving collimator”) facing the emission end surface of the analyzer 27 of FIG.
29 is arranged, and a light receiving collimator (hereinafter, referred to as “second light receiving collimator”) 30 on the small current detection side is arranged so as to face the emission end surface of the second analyzer 28.

Further, the current sensor of this embodiment is composed of the substrate 21.
An iron core 31 for housing the Faraday element 22 in the gap portion 31a in a state perpendicular to the is provided. The iron core 31 is
It has a ring shape having a predetermined inner diameter, and a part thereof is notched to a length such that the Faraday element 22 can be accommodated from the outside of the right-angle prisms 24 and 26, and a gap portion 31a is formed. The gap 31a of the iron core 31 is
The Faraday element 22 is arranged so as to cover only the region where the second linearly polarized light component propagates from above in FIG. The electric wire 32 through which the measured current I flows is arranged at the center of the iron core 31 with a gap.

In the present embodiment configured as described above, when the electric current 32 to be measured is a large current flowing through the electric wire 32, a magnetic field is generated when the electric current 32 to be measured flows through the electric wire 32, and the electric current I to be measured is generated. Creates a magnetic field H1 of a predetermined strength at the first linearly polarized light passing position in the Faraday element 22. The direction of the magnetic field H1 is the direction of the arrow shown in the figure, which coincides with the propagation direction of the first linearly polarized light component in the Faraday element 22.

When the measurement light is emitted from the light-transmitting collimator 25, the first linearly polarized light component is reflected by the polarization beam splitter 23 at an angle of 90 degrees, and the Faraday element 22 to which the magnetic field H1 is applied is in the magnetic field direction. It is incident at parallel angles. Due to the Faraday effect that acts when the first linearly polarized light component passes through the Faraday element 22, the polarization plane of the first linearly polarized light component rotates by an angle proportional to the magnetic field H1. The first linearly polarized light component whose polarization plane is rotated is emitted from the Faraday element 22 and is incident on the first analyzer 27,
Only a predetermined one component of the first linearly polarized light component is extracted by the first analyzer 27 and received by the first light receiving collimator 29. The magnetic field H1 is obtained from the amount of light received by the first light receiving collimator 29, and the measured current I is calculated from the obtained magnetic field H1.

Further, when the electric current 32 to be measured is a small current flowing through the electric wire 32, a magnetic field is generated when the electric current I to be measured flows through the electric wire 32, and a magnetic field H2 having a predetermined strength corresponding to the magnetic field is generated. Occurs in the gap portion 31a. That is, the Faraday element 2 sandwiched between the pair of right-angle prisms 24 and 26.
In the passage of the second linearly polarized light component of 2, the iron core 3 with a gap
1 creates a magnetic field H2.

When the measurement light is emitted from the light-transmitting collimator 25, the second linearly polarized light component is transmitted through the polarization beam splitter 23 and is incident on the rectangular prism 24, where it is reflected at an angle of 90 degrees and a magnetic field H2 is applied. The light is incident on the Faraday element 22 at an angle parallel to the magnetic field direction. Second
When the linearly polarized light component of is passed through the Faraday element 22, its plane of polarization is rotated by an angle proportional to the magnetic field H2. The second linearly polarized light component whose polarization plane is rotated is emitted from the Faraday element 22, is reflected by the rectangular prism 26, and is incident on the second analyzer 28. Only a predetermined one component of the first linearly polarized light component whose polarization plane is rotated by the Faraday element 22 is extracted by the second analyzer 28 and received by the second light receiving collimator 30. Second light receiving collimator 3
The magnetic field H2 can be obtained from the amount of light received at 0, and the measured current I can be calculated from the obtained magnetic field H2.

As described above, according to this embodiment, the first linearly polarized light component, which is the reflected light at the polarization beam splitter 23, is used as the measurement light for detecting the large current, and the first linearly polarized light component is transmitted through the polarization beam splitter 23. The second linearly polarized light component is used as measurement light for detecting a small current, and the first and second linearly polarized light components are passed through one Faraday element 22 and
Since both ends of the passage of the linearly polarized light component of are accommodated in the gap portion 31a of the iron core 31, the light transmitting collimator 2
5. The polarizer (polarizing beam splitter 23) and the Faraday element 22 can be commonly used for both large current detection and small current detection, and the number of parts can be reduced. Further, since the functions of the two sensors for large current detection and small current detection can be realized by the constituent elements arranged on one substrate 21 on the same plane, the sensor as a whole can be made compact. Further, since the reflected light from the polarization beam splitter 23 is used for detecting a large current and the transmitted light is used for detecting a small current,
The measuring light can be used efficiently.

As shown in FIG. 2, the current sensor of the above embodiment can be applied to equipment in which the electric wire 32 through which the current I to be measured flows is arranged in a gas-tight type storage container 40. A gas purging valve 41 for filling the container with a gas for gas-insulating the electric wire 32 is attached to the storage container 40. The present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

[0026]

As described above in detail, according to the present invention, one of the two polarization components separated by the polarization beam splitter is used for detecting a large current, and the other is used for detecting a small current. As a result, it is possible to reduce the number of parts and to configure a sensor that can detect both large and small currents on the same plane, making it easy to downsize and compact the entire sensor, and to efficiently measure light. Can be used.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a current sensor according to an embodiment of the present invention.

FIG. 2 is a view showing a gas-tight type storage container equipped with the current sensor of the one embodiment.

FIG. 3 is a configuration diagram of a conventional current sensor for detecting a large current.

FIG. 4 is a configuration diagram of a conventional small current detection current sensor.

[Explanation of symbols]

21 ... Substrate, 22 ... Faraday element, 23 ... Polarization beam splitter, 24, 26 ... Right angle prism, 27 ... First analyzer, 28 ... Second analyzer, 29 ... First light receiving collimator, 30 ... Second Light receiving collimator, 31 ... Iron core, 31
a ... Gap part, 32 ... Electric wire, 40 ... Storage container.

Claims (5)

[Claims] 1. A detection signal, which receives linearly polarized light whose polarization plane is rotated according to the strength of a magnetic field generated by the current to be measured, and which is based on the rotation amount of the polarization plane and which corresponds to the current value of the current to be measured. In a current sensor that outputs, a light-transmitting collimator that emits light, a polarization beam splitter that splits the light emitted from this light-transmitting collimator into reflected light and transmitted light to create two linearly polarized light, and this polarization beam splitter A first light propagation path that makes one of the created linearly polarized light incident and propagates in the magnetic field direction by the current to be measured and rotates the polarization plane of the linearly polarized light according to the strength of the magnetic field; A first analyzer on which one linearly polarized light emitted from the light propagation path is incident, a first light receiving collimator for receiving the light transmitted through the first analyzer, and the other of the other formed by the polarization beam splitter. straight A second light propagation path to rotate in accordance with the polarization plane of the linearly polarized light to the intensity of the magnetic field with propagating in a predetermined direction polarization incident, the second
Second linearly-polarized light emitted from the second light propagation path, a second light-receiving collimator that receives light transmitted through the second analyzer, and both ends of the second light-propagation path. A current sensor, comprising: an iron core with a gear that sandwiches the core in a gap. 2. The current sensor according to claim 1, wherein the first light propagation path and the second light propagation path are formed in one Faraday element. 3. A light-transmitting collimator, a polarization beam splitter, first and second light propagation paths, first and second analyzers, and first and second light-receiving collimators are arranged on the same substrate surface. The current sensor according to claim 1 or 2, characterized in that. 4. The current sensor according to claim 1, wherein the first and second light propagation paths or the Faraday element is made of zinc selenium (ZnSe). 5. A gas-sealed storage container in which a conducting wire through which a current to be measured flows is housed in a gas-insulated manner, and a plurality of gas purging valves are attached, wherein the current sensor according to any one of claims 1 to 4. To
A gas-tight storage container, characterized in that the core of the geared core is arranged in the storage container so that the conductors pass through it.