WO2010134327A1 - 電流測定装置 - Google Patents
電流測定装置 Download PDFInfo
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- WO2010134327A1 WO2010134327A1 PCT/JP2010/003348 JP2010003348W WO2010134327A1 WO 2010134327 A1 WO2010134327 A1 WO 2010134327A1 JP 2010003348 W JP2010003348 W JP 2010003348W WO 2010134327 A1 WO2010134327 A1 WO 2010134327A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
- G01R15/245—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect
- G01R15/246—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect based on the Faraday, i.e. linear magneto-optic, effect
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
- G01R15/245—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/32—Compensating for temperature change
Definitions
- the present invention relates to a current measurement device using the Faraday effect, and relates to an improvement of a reflection type current measurement device that allows light to be incident from one end side of a sensor optical fiber and reflected at the other end side.
- Patent Document 1 discloses a reflection-type current measurement device that uses the Faraday effect in which the plane of polarization of light rotates by the action of a magnetic field.
- FIG. 21 shows a current measuring apparatus 100 shown in FIG. 18 of WO 2006/022178 of Patent Document 1 (here, the reference number in the diagram of Patent Document 1 is changed and described).
- the current measuring device 100 is a reflection type current measuring device 100 in which a lead glass fiber is used for the sensor optical fiber 101 and a mirror 102 is disposed at the other end of the sensor optical fiber 101.
- the sensor optical fiber 101 is installed around the conductor 103 through which the current to be measured flows to detect the current to be measured, and linearly polarized light incident from one end of the sensor optical fiber 101 is reciprocated by the mirror 102.
- the basic configuration is to measure the Faraday rotation angle of linearly polarized light rotated by the magnetic field of the current to be measured.
- 104 is a light source
- 105 is a circulator
- 106 is a polarization separation unit such as calcite
- 107 is a Faraday rotator made of a permanent magnet (107a) and a ferromagnetic crystal (107b) such as YIG
- 108a and 108b are photodiodes ( PD)
- 109a and 109b are amplifiers (A)
- 110a and 110b are band-pass filters (BPF)
- 111a and 111b are low-pass filters (LPF)
- 112a and 112b are the ratios of the AC and DC components of the electrical signal.
- Reference numeral 115 denotes an optical system
- 116 denotes a signal processing circuit.
- the linearly polarized light corresponding to the ordinary ray passes through the ferromagnetic crystal 107 b and then enters the sensor optical fiber 101. To do. Further, the light is reflected by the mirror 102, passes through the sensor optical fiber 101 and the ferromagnetic crystal 107 b again, and enters the polarization separation unit 106.
- the linearly polarized light Since the plane of polarization of the linearly polarized light rotates when the linearly polarized light passes through the ferromagnetic crystal 107b and the sensor optical fiber 101, the linearly polarized light is separated into two perpendicular polarization components by the polarization separation unit 106. Is done. The separated polarized light components are guided to the light receiving elements 108a and 108b, which are photodiodes, by the circulator 105 and the polarization separation unit 106 in FIG.
- a current or voltage proportional to the intensity of the received light is output as an electrical signal.
- these electric signals pass through amplifiers 109a and 109b, they are separated into AC and DC components by BPFs 110a and 110b and LPFs 111a and 111b, and the ratios of AC and DC components are obtained by dividers 112a and 112b.
- the polarity of the output signal from the divider 112 a is inverted by the polarity inverter 113.
- an average of the signals Sa and Sb output from the polarity inverter 113 and the divider 112b is obtained by the multiplier 114, and this average is output as a measured value Sout for the current to be measured of the current measuring device 100.
- the Faraday rotation angle of the Faraday rotator 107 used in the current measuring device has a characteristic (temperature characteristic) that depends on the ambient temperature. Therefore, in the conventional Faraday rotator 107, in order to reduce the temperature characteristic of the Faraday rotator 107, the signal processing circuit 116 and the photoelectric conversion elements (photodiodes 108a and 108b) are duplexed as shown in FIG. By determining the average of the signals Sa and Sb, the influence on the output Sout caused by the temperature dependence of the Faraday rotation capability of the ferromagnetic Faraday rotator 107 is reduced.
- the sensor optical fiber 101 since the sensor optical fiber 101 also has a temperature characteristic of a specific error due to the temperature dependence of the Verde constant and the Faraday rotation angle, not only the compensation of the Faraday rotator 107 but also the compensation (reduction of the temperature characteristic of the sensor optical fiber 101). ) Is also necessary. Compensation of the Faraday rotator 107 and the sensor optical fiber 101 has been performed by the signal processing circuit 116, but is not complete. Such compensation is not necessary for improving the reliability of the current measuring apparatus 100. Compensation at 115 is desired.
- FIG. 22a shows the relationship between the error rate of the modulation signals Sa and Sb and the temperature in the case of FIG. 21, and FIG. 22b shows the temperature characteristics of the optical fiber 101 for sensors. That is, even if the average processing of the modulation signals Sa and Sb is performed as shown in FIG. 22a, the problem as shown in FIG. 22b, that is, when the sensor optical fiber 101 is a lead glass fiber, the Verde constant of the sensor optical fiber 101 is obtained. There remains a problem that the temperature characteristics of the sensor output due to temperature dependence cannot be completely compensated.
- a current measuring device 100 that completely compensates for the temperature characteristics of both the Faraday rotator 107 and the sensor optical fiber 101 has been desired.
- the current measuring device of the present invention has been made on the basis of the above problems, and its purpose is to compensate the temperature characteristics of the ratio error between the optical fiber for the sensor and the Faraday rotator with the optical system of the current measuring device. Is to provide a simple current measuring device.
- the purpose is to keep the fluctuation range of the ratio error in the output of the current measuring device within a range of ⁇ 0.5%.
- the current measuring device includes at least a signal processing circuit including a sensor optical fiber, a polarization separation unit, a Faraday rotator, a light source, and a photoelectric conversion element
- the sensor optical fiber is installed around the outer circumference of the conductor through which the current to be measured flows, and has one end for incident linearly polarized light and the other end for reflecting the incident linearly polarized light
- the polarization separation unit is provided on one end side of the sensor optical fiber
- the Faraday rotator is disposed between one end side of the sensor optical fiber and the polarization separation unit, Furthermore, By setting the Faraday rotation angle at the time of magnetic saturation of the Faraday rotator to 22.5 ° + ⁇ ° at a temperature of 23 ° C., the ratio error in the measured value of the measured current output from the signal processing circuit is reduced.
- the current measuring device is characterized in that the fluctuation range is set within a range of ⁇ 0.5%.
- the temperature range in which the fluctuation range is set within a range of ⁇ 0.5% is 100 ° C. This is a current measuring device.
- the current measuring device according to claim 3 of the present invention is the current measuring device according to claim 2, wherein the temperature range of 100 ° C. is ⁇ 20 ° C. or more and 80 ° C. or less.
- the Faraday rotator has a temperature characteristic of the Faraday rotation angle at which the Faraday rotation angle at the time of magnetic saturation changes into a quadratic curve with a change in temperature.
- the Faraday rotator is constituted by two or more Faraday elements. Device.
- the current measuring device according to claim 6 of the present invention is the current measuring device according to claim 5, wherein the two or more Faraday elements have different Faraday rotation angles.
- the fluctuation range of the ratio error in the measured value of the measured current output from the signal processing circuit is set within a range of ⁇ 0.2%.
- a temperature range in which the fluctuation range is set within a range of ⁇ 0.2% is 100 ° C. This is a current measuring device.
- the current measuring device according to claim 9 of the present invention is the current measuring device according to claim 8, wherein the temperature range of 100 ° C. is ⁇ 20 ° C. or higher and 80 ° C. or lower.
- the current measuring device according to claim 10 of the present invention is the current measuring device according to any one of claims 1 to 9, wherein the sensor optical fiber is a lead glass fiber.
- the rotation angle of the Faraday rotator is changed from 22.5 ° by ⁇ ° to reduce the fluctuation range of the Faraday rotator specific error.
- the fluctuation range of the ratio error in the measured value of the current to be measured output from the signal processing circuit is suppressed within a range of ⁇ 0.5%. Therefore, the temperature characteristic compensation of the ratio error in the measured value can be performed by an optical system called a Faraday rotator, so that the reliability of the current measuring device is improved and the fluctuation range of the ratio error is ⁇ 0.5%.
- the relative error fluctuation range of ⁇ 0.5% or ⁇ 0.2% is in a temperature range of 100 ° C. ( ⁇ 20 ° C. to 80 ° C.).
- a current measuring device having practicality that covers a normal temperature range of ⁇ 10 ° C. to 40 ° C.
- the Faraday rotator having a temperature characteristic of the Faraday rotation angle in which the Faraday rotation angle at the time of magnetic saturation changes in a quadratic curve as the temperature rises.
- a Faraday rotator having a desired rotation angle can be obtained stably.
- the Faraday rotation angle of each Faraday element can be configured to be different, so that the temperature characteristic of each Faraday element is set to a desired characteristic. I can do it.
- the temperature characteristic of the specific error of the lead glass fiber is added when the fluctuation range of the specific error of the current measuring device is reduced. Then adjust the rotation angle ⁇ ° of the Faraday rotator.
- the block diagram which shows the best form of the electric current measurement apparatus concerning this invention. Schematic representation of the temperature characteristics of the specific error in the temperature range of -20 ° C to 80 ° C of a current measuring device equipped with a Faraday rotator having a Faraday rotation angle of 45 ° at a temperature of 23 ° C when linearly polarized light is transmitted back and forth. Shown graphically.
- the graph which shows typically the Faraday rotation angle temperature dependence at the time of changing in Faraday rotation angle in the temperature of 23 degreeC from 22.5 degrees only (alpha), and reciprocating.
- FIG. 2 is an explanatory diagram illustrating a polarization state of light from a light source to a reflection film in the current measurement device of FIG. 1.
- FIG. 2 is an explanatory diagram illustrating a polarization state of light from a light source to a reflection film in the current measurement device of FIG. 1.
- FIG. 2 is an explanatory diagram illustrating a polarization state of light from a light source to a reflection film in the current measurement device of FIG. 1.
- FIG. 2 is an explanatory diagram illustrating a polarization state of light from a light source to a reflection film in the current measurement device of FIG. 1.
- FIG. 3 is an explanatory diagram illustrating a polarization state of light that is reflected by a reflection film and reaches the first and second photoelectric conversion elements in the current measurement device of FIG. 1.
- FIG. 3 is an explanatory diagram illustrating a polarization state of light that is reflected by a reflection film and reaches the first and second photoelectric conversion elements in the current measurement device of FIG. 1.
- FIG. 3 is an explanatory diagram illustrating a polarization state of light that is reflected by a reflection film and reaches the first and second photoelectric conversion elements in the current measurement device of FIG. 1.
- FIG. 3 is an explanatory diagram illustrating a polarization state of light that is reflected by a reflection film and reaches the first and second photoelectric conversion elements in the current measurement device of FIG. 1.
- FIG. 3 is an explanatory diagram illustrating a polarization state of light that is reflected by a reflection film and reaches the first and second photoelectric conversion elements in the current measurement device of FIG. 1.
- the graph which shows an example of the temperature characteristic of the ratio error in the measured value of the to-be-measured current output from a signal processing circuit in the current measuring device of FIG.
- the graph which shows the temperature characteristic of the ratio error in Example 3 of the current measuring apparatus of this invention The block diagram which shows the conventional electric current measurement apparatus.
- the partial schematic diagram which shows the example of a change of each end surface shape of a 1st optical fiber and a 2nd optical fiber.
- FIG. 1 is a block diagram showing the best mode of a current measuring apparatus 1 according to the present invention.
- the current measuring apparatus 1 shown in the figure includes a sensor optical fiber 2, a polarization separator 8, a Faraday rotator 7, a light source 13, and a signal processing circuit (not shown) described later.
- the sensor optical fiber 2 is installed around the outer circumference of the conductor 5 through which the current I to be measured flows.
- the sensor optical fiber 2 is composed of a lead glass fiber, and propagates the linearly polarized light LO and the linearly polarized light LR reflected by the other end of the sensor optical fiber 2 inside.
- a reflective film 6 is provided as a reflective material on the other end of the sensor optical fiber 2.
- an arbitrary reflective material other than the reflective film 6 can be used for the other end, for example, gold, silver, copper, chromium, aluminum, etc., which have a low absorption rate and high reflectivity.
- a mirror made of a metal having a high rate or a dielectric multilayer film may be provided.
- the optical circuit unit 3 makes one of the ordinary and extraordinary rays linearly polarized light incident on the sensor optical fiber 2 and further detects the Faraday rotation angle of the polarization plane of the linearly polarized light emitted from the sensor optical fiber 2. In order to achieve this, it is a circuit that separates the linearly polarized light emitted from the sensor optical fiber 2 into an ordinary ray and an extraordinary ray.
- the optical circuit section 3 includes a Faraday rotator 7 (hereinafter referred to as “first Faraday rotator 7”), a birefringent element 8 (hereinafter referred to as “polarization separation section 8”) as a polarization separation section, a first An optical fiber 9, a second optical fiber 10, and a lens 11 are provided.
- the first Faraday rotator 7 is a light transmission type optical element having a permanent magnet 7 a provided on the outer periphery, is formed of a bismuth-substituted garnet single crystal, and is formed on one end side 2 a that is the incident end of the sensor optical fiber 2.
- the polarization planes of the incident linearly polarized light LO and the reflected linearly polarized light LR that are provided in the vicinity are rotated by the Faraday rotation angle due to magnetic saturation.
- the polarization plane of the linearly polarized light LO before passing through the first Faraday rotator 7 and the polarization plane of the linearly polarized light LR after passing through the first Faraday rotator 7 are not affected by the current I to be measured.
- the purpose of rotating the polarization plane of the linearly polarized light by 45 ° is to separate the linearly polarized light LR into the ordinary ray L1 and the extraordinary ray L2 in the polarization separation unit 8, and to linearly polarize LO by the ordinary ray L1 and the extraordinary ray L2.
- the Faraday rotation angle of LR is obtained, and the value of the measured current I is calculated from the Faraday rotation angle.
- the total Faraday rotation angle at the time of magnetic saturation when linearly polarized light LO and LR are transmitted in a reciprocating manner is set so as to slightly change from 45 ° at a temperature of 23 ° C.
- the reason why the temperature of the Faraday rotation angle is defined as 23 ° C. is that the applicant has set it as the temperature that can be measured most easily when measuring the Faraday rotation angle at room temperature. Therefore, the Faraday rotation angle when the linearly polarized light LO or LR passes through the first Faraday rotator 7 once is 22.5 ° + a slight change ⁇ °.
- 2 shows that the measured current value output from the signal processing circuit of the current measuring device having a Faraday rotation angle of 45 ° at a temperature of 23 ° C. when linearly polarized light is transmitted back and forth is ⁇ 20 ° C. to 80 ° C.
- 2 is a graph schematically showing a ratio error-temperature characteristic in the temperature range of FIG. The basis for defining the temperature range to be ⁇ 20 ° C. or higher and 100 ° C. or lower is 100 ° C. is based on a request from the applicant's customer.
- the ratio error of the current measuring device increases nonlinearly as the temperature rises.
- the rotation angle is reciprocated as shown in FIG. 45 ° + 2 ⁇ °.
- the curve of the temperature characteristic of the ratio error of the current measuring device shifts to the high temperature side.
- the rotation angle ⁇ ° can be arbitrarily set within a range in which the fluctuation range of the ratio error decreases when the curve of the temperature characteristic of the ratio error is shifted.
- the basic concept of the present invention is to reduce the fluctuation range of the ratio error of the current measuring device by changing the Faraday rotation angle from 22.5 ° by ⁇ °.
- the polarization separation unit 8 is a light transmission type optical element, and is installed on the photoelectric conversion unit 4 side of the first Faraday rotator 7 in the vicinity of the one end side 2 a that is the incident end of the sensor optical fiber 2. Therefore, the Faraday rotator 7 is disposed between the one end side 2 a of the sensor optical fiber 2 and the polarization separation unit 8.
- the polarization separation unit 8 is composed of a birefringent element as described above, and transmits linearly polarized light as it is when linearly polarized light is incident perpendicular to the crystal axis, and linearly polarized light when linearly polarized light is incident along the crystal axis. It has a function as a polarization separation element that emits light after being translated.
- the polarization separation unit 8 separates the linearly polarized light LR from the sensor optical fiber 2 into an ordinary ray L1 and an extraordinary ray L2 that are orthogonal to each other and transmits linearly polarized light LO emitted from the light source 13 described later. It has a function to make it.
- the material of the polarization separation unit 8 can be selected from rutile, YVO4, lithium niobate, and calcite.
- the birefringent element selected from such a material is processed into a flat plate in which the opposing light incident / exit optical surfaces are parallel to each other with a predetermined thickness to form a polarization separation unit 8, and one of the parallel optical surfaces is
- the first optical fiber 9 and the second optical fiber 10 are installed so as to face the end faces 9 a and 10 a and the other optical surface faces the lens 11.
- the first optical fiber 9 is composed of a polarization-preserving fiber, and an end surface 9a on one end side is disposed in the vicinity of the polarization separation unit 8. Or you may arrange
- the second optical fiber 10 is composed of a single mode optical fiber, a multimode optical fiber, a polarization-maintaining fiber, or the like, and an end face 10a on one end side is disposed in the vicinity of the polarization separation section 8. Or you may arrange
- the first and second optical fibers 9 and 10 have end faces 9a and 10a on one end side disposed on the same plane, and are further held by a ferrule 12 having a two-core structure with a predetermined interval therebetween.
- the predetermined interval is set in accordance with the thickness of the parallel plate-shaped polarization separation section 8 and the physical properties of the selected material. By making the predetermined interval coincide with the separation interval of the polarization separator 8, the ordinary ray L 1 and the extraordinary ray L 2 can be incident on the cores of the optical fibers 9 and 10.
- the means for holding the first and second optical fibers 9 and 10 at a predetermined interval is not limited to the ferrule 12, and includes, for example, two parallel V-shaped grooves, and the optical fibers 9 and 10 are placed in the V-groove. It may be an array substrate that can be positioned in both directions.
- the lens 11 is constituted by a single lens, and is disposed between the first Faraday rotator 7 and the polarization separation unit 8, and each imaging point is one end 2 a of the sensor optical fiber 2. And set to each core of the end face 9 a of the first optical fiber 9.
- the one end 2a of the sensor optical fiber 2 and the one end surface 9a of the first optical fiber 9 are upright surfaces orthogonal to the respective optical axes, and the image forming point of the lens 11 is the position of each fiber. It is set on the approximate center of the core.
- end faces 9a and 10a may be modified so as to be obliquely polished as shown in FIG.
- the positions of the end faces 9a and 10a are matched with the focal lengths of the ordinary ray L1 and the extraordinary ray L2 in the lens 11, and the first optical fiber 9 and the second light are matched.
- the coupling efficiency of the fiber 10 can be improved.
- the photoelectric conversion unit 4 includes a light source 13, a lens 14, a polarization separation prism 15, two first and second photoelectric conversion elements 16 and 17, and a second Faraday rotator 18.
- the light source 13 includes a semiconductor laser (LD), a light emitting diode (LED), a super luminescent diode (SLD), an ASE light source, and the like, and emits light having a predetermined wavelength ⁇ .
- the lens 14 is installed in front of the light source 13, and combines the light emitted from the light source 13 to enter the polarization separation prism 15.
- the polarization separation prism 15 linearly polarizes the light emitted from the light source 13 and couples it to the optical fiber 9, and converts the ordinary light L 1 that is the light emitted from the first optical fiber 9 to the first photoelectric conversion element 16. Reflect.
- the 1st and 2nd photoelectric conversion elements 16 and 17 are comprised with a photodiode (PD) etc., receive light and convert it into an electrical signal.
- PD photodiode
- the second Faraday rotator 18 is a light transmissive optical element having a permanent magnet 18 a on the outer periphery, is formed of a bismuth-substituted garnet single crystal, is installed in front of the polarization separation prism 15 and is incident on the linearly polarized light. Rotate 45 °. As described above, the second Faraday rotator 18 for rotating the linearly polarized light by 45 ° is provided so that the polarization plane of the linearly polarized light L1 in the reverse direction returning to the polarization plane of the linearly polarized light LO in the forward direction is 90 °. This is because all the linearly polarized light L1 is reflected by the polarization separation prism 15 and is incident on the first photoelectric conversion element 16 by being rotated.
- the other end 9b of the first optical fiber 9 is disposed close to the front of the second Faraday rotator 18.
- light emitted from the second optical fiber 10 is incident on the second photoelectric conversion element 17.
- FIGS. 5 a to 5 d are explanatory views showing the polarization state of light from the light source 13 to the reflection film 6, and FIGS. 6 a to 6 e are reflected by the reflection film 6 and the first and second photoelectric conversion elements 16 and 17. It is explanatory drawing which shows the polarization state of the light until it reaches to.
- the light emitted from the light source 13 passes through the lens 14 and the polarization separation prism 15 to be linearly polarized, and the linearly polarized light LO (see FIG. 5b) is incident on the second Faraday rotator 18 to be polarized.
- the light is incident on the first optical fiber 9 as linearly polarized light LO (see FIG. 5c) whose surface is rotated by 45 °.
- the linearly polarized light LO propagates through the first optical fiber 9 with the polarization plane preserved, and is incident on the polarization separating unit 8.
- the direction of the crystal axis on the optical surface of the polarization separation element 8 is set so as to be orthogonal to the polarization plane of the linearly polarized light LO emitted from the first optical fiber 9. Accordingly, the linearly polarized light LO incident on the polarization separation unit 8 is transmitted as an ordinary ray without causing birefringence inside the polarization separation unit 8 and remains in the polarization state when entering the polarization separation unit 8. It is emitted from.
- the polarization plane of the linearly polarized light LO emitted from the polarization separator 8 is rotated by 22.5 ° + ⁇ ° when passing through the first Faraday rotator 7 after passing through the lens 11 (see FIG. 5d). As described above, the light is incident on the one end 2 a of the sensor optical fiber 2 by the action of the lens 11.
- the linearly polarized light LO that has entered the sensor optical fiber 2 propagates through the inside thereof, reaches the other end, is reflected by the reflecting film 6, and returns to the one end 2a again.
- the linearly polarized light LO and LR are affected by the magnetic field generated by the current I to be measured, and the plane of polarization of the current I is measured by the Faraday effect.
- Rotate by an angle ⁇ ° according to. ⁇ ° is a Faraday rotation angle generated depending on the magnetic field intensity due to the current I to be measured when the linearly polarized light LO and LR reciprocate in the sensor optical fiber 2.
- the polarization plane of the linearly polarized light LR (see FIG. 6a) emitted from the one end 2a is further rotated by 22.5 ° + ⁇ ° (see FIG. 6b) when passing through the first Faraday rotator 7 again, and the lens 11 And is incident on the polarization separation unit 8. Therefore, the polarization plane of the linearly polarized light LR after passing through the first Faraday rotator 7 is (45 ° + 2 ⁇ ° + ⁇ °) with respect to the polarization plane of the linearly polarized light LO before passing through the first Faraday rotator 7. It will be rotated by an angle.
- the polarization plane of the linearly polarized light LR incident on the polarization separation unit 8 is shifted by (45 ° + 2 ⁇ ° + ⁇ °) with respect to the polarization plane of the linearly polarized light LO before passing through the first Faraday rotator 7. .
- the linearly polarized light LR is separated into the ordinary ray L1 and the extraordinary ray L2 having polarization planes orthogonal to each other in the polarization separation unit 8 (see FIG. 6c).
- the ordinary ray L1 is emitted along a plane orthogonal to the plane including the crystal axis and the optical axis of the polarization separation unit 8, and the extraordinary ray L2 is emitted from a polarization plane that vibrates in the plane including the crystal axis and the optical axis. (See FIG. 6d). If rotation of the polarization planes of the linearly polarized light LO and LR due to the current I to be measured occurs, the amount of the ordinary ray L1 and the extraordinary ray L2 changes at the time of separation. Therefore, the rotation of the polarization plane changes the light intensity. Is detected by the photoelectric conversion elements 16 and 17.
- the ordinary ray L1 emitted from the polarization separation unit 8 enters the first optical fiber 9 from the end face 9a, is guided to the photoelectric conversion unit 4 and the signal processing circuit, and further has a 45 ° polarization plane by the second Faraday rotator 18. Rotated (see FIG. 6e. In order to ensure the visibility of the figure, the ordinary ray L1 is enlarged in FIG. 6e) and is incident on the polarization separation prism 15.
- the plane of polarization of the ordinary ray L1 incident on the polarization separation prism 15 is orthogonal to the plane of polarization of the linearly polarized light LO emitted from the light source 13 and transmitted through the polarization separation prism 15 (see FIGS. 5b and 6e). ),
- the ordinary ray L1 is reflected by the polarization separation prism 15 and received by the first photoelectric conversion element 16.
- the extraordinary ray L2 enters the second optical fiber 10 from the end face 10a, is guided to the photoelectric conversion unit 4 and the signal processing circuit, and is received by the second photoelectric conversion element 17.
- the electric signal converted into the electric signal by the photoelectric conversion elements 16 and 17 is, for example, a signal processing circuit 116 as shown in FIG. 21 (however, the photodiode 108a is converted into the photoelectric conversion element 16 and the photodiode 108b is converted into the photoelectric signal).
- the average of the degree of modulation (AC component / DC component) of each of the two current signals detected by the first photoelectric conversion element 16 and the second photoelectric conversion element 17 Is calculated and finally the linearly polarized light LR is converted into an electric quantity, whereby the magnitude of the current I to be measured can be obtained.
- FIG. 7 shows an example of a temperature characteristic graph of the ratio error in the measured value of the current I to be measured output from the signal processing circuit in the current measuring device 1.
- the fluctuation range of the ratio error in the measured value of the measured current I output from the signal processing circuit is set within a range of ⁇ 0.5%.
- the above ⁇ 0.5% is realized over a temperature range of 100 ° C. ( ⁇ 20 ° C. to 80 ° C.).
- the reason why the temperature range is set to ⁇ 20 ° C. or higher and 100 ° C. or lower is 100 ° C. considering the practicality of covering a normal temperature range of ⁇ 10 ° C. or higher and 40 ° C. or lower.
- the setting within ⁇ 0.5% of the fluctuation range of the ratio error is performed by adjusting the rotation angle of the first Faraday rotator 7 as described above.
- the lead glass fiber used for the sensor optical fiber 2 has a temperature characteristic of a specific error as shown in FIG. Therefore, when changing the rotation angle of the first Faraday rotator 7 from 22.5 ° by ⁇ ° to reduce the fluctuation range of the specific error of the current measuring device 1, the temperature characteristic of the specific error of the lead glass fiber is added.
- the fluctuation range of the ratio error in the measured value of the measured current I output from the signal processing circuit is within ⁇ 0.5% over the temperature range of ⁇ 20 ° C. to 80 ° C.
- the angle of ⁇ ° may be adjusted.
- the first Faraday rotator 7 can be changed to a current measuring device 20 configured by two Faraday elements 19a and 19b having different Faraday rotation angles, for example, as shown in FIG. It is.
- the total Faraday rotation angle at the time of magnetic saturation when the linearly polarized light LO and LR are reciprocally transmitted through the two Faraday elements 19a and 19b is set so as to slightly change from 45 °.
- the total of the Faraday rotation angles when the linearly polarized light LO or LR is transmitted once through each of the two Faraday elements 19a and 19b may be changed to be 22.5 ° + a slight change ⁇ °.
- the number of Faraday elements is not limited to two, and the first Faraday rotator 7 can be configured with three or more.
- FIG. 10 and 11 are graphs schematically showing temperature characteristics of the Faraday rotation angles of the Faraday elements 19a and 19b.
- FIG. 12 shows the temperature characteristics of the Faraday rotation angle when the temperature characteristics of the Faraday rotation angles of the Faraday elements are combined.
- the rotation angle of the first Faraday element 19a has a quadratic curve-like temperature dependency.
- the rotation angle of the second Faraday element 19b uniformly decreases in inverse proportion to the temperature rise over the temperature range of ⁇ 20 ° C. to 80 ° C. Therefore, when the temperature characteristics of the Faraday rotation angle of the first Faraday element 19a and the second Faraday element 19b are combined, the temperature characteristic of the Faraday rotation angle that decreases in a quadratic curve as shown in FIG. Indicates.
- the temperature characteristic of the specific error of the lead glass fiber used for the sensor optical fiber 2 increases uniformly in proportion to the temperature rise. Accordingly, by providing the Faraday elements 19a and 19b with the decrease in the Faraday rotation angle in the high temperature region, when the temperature characteristic of the specific error of the lead glass fiber used in the sensor optical fiber 2 is added, the high temperature region Since the change in the relative error of the lead glass fiber is compensated for by the decrease in the Faraday rotation angle in FIG. 13, the fluctuation range of the ratio error in the measured value of the measured current I output from the signal processing circuit is shown in FIG. It becomes possible to keep within a range of ⁇ 0.5% (or ⁇ 0.2%) over a temperature range of ⁇ 20 ° C. to 80 ° C.
- the current measuring device 1 can have a single first Faraday rotator 7, so that the configuration of the current measuring device can be simplified accordingly.
- the fluctuation range of the ratio error in the measured value of the measured current I output from the signal processing circuit can be easily adjusted.
- the current measuring device 1 is the most preferred embodiment.
- the first Faraday rotator 7 is composed of two or more Faraday elements. What is necessary is just to comprise.
- the Faraday rotation angle of each Faraday element is set to be different so that the temperature characteristic of each Faraday element is set to a desired characteristic. I can do it.
- FIG. 1 shows an example in which a magnetic garnet having a temperature characteristic of a Faraday rotation angle as shown in FIG. 11 used in an optical isolator is used as the first Faraday rotator 7 in FIG.
- a Faraday rotator in which the Faraday rotation angle at a temperature of 23 ° C. was set to 22.5 ° + 1.0 ° was used. That is, ⁇ 1.0 ° was set, and the total Faraday rotation angle at the time of magnetic saturation when linearly polarized light LO and LR were transmitted in a reciprocating manner was set to 47.0 °.
- the ratio error based on 23 ° C. can be kept within ⁇ 0.01 to 0.42%. It turns out that it is possible. That is, the fluctuation range of the ratio error is in the range of 0.43% over the temperature range of ⁇ 20 ° C. to 80 ° C.
- Equation 1 The rotation angle-temperature dependence of the magnetic garnet in the reciprocation was expressed by the following quadratic expression (Equation 1), and the minimum value of the ratio error fluctuation range for the coefficient a and the coefficient b was calculated.
- the coefficient c was set so that the ratio error fluctuation range had a minimum value.
- Table 2 shows the relationship between the ratio error fluctuation range and the coefficients a and b.
- Table 3 shows the relationship between the Faraday rotation angle adjustment ⁇ °, the coefficient a, and the coefficient b at a temperature of 23 ° C. when the ratio error fluctuation width is the minimum value as shown in Table 2.
- Tables 2 and 3 are point-symmetric with respect to 0 of coefficient a and coefficient b. According to Table 2, the ratio error fluctuation range is minimized when the coefficient a and the coefficient b are -0.0001 and -0.02, respectively, and when the coefficient a and the coefficient b are 0.0001 and 0.02, respectively. Yes, the sign of the rotation angle adjustment amount ⁇ ° at that time is plus in the former from Table 3 and minus in the latter. Since a general magnetic garnet has a temperature characteristic of an upward convex curve and a Faraday rotation angle in which the rotation angle decreases as the temperature rises, the signs of the coefficient a and the coefficient b are negative.
- the coefficient a of the temperature characteristic of the rotation angle of the magnetic garnet should be set to ⁇ 0.0001 and the coefficient b close to ⁇ 0.02 in order to reduce the ratio error fluctuation range.
- the rotation angle adjustment ⁇ ° is about 1.66 °.
- FIG. 9 An embodiment using the two Faraday elements 19a and 19b shown in FIG. 9 is shown.
- the Faraday element 19a in FIG. 9 a magnetic garnet having a quadratic temperature dependence is used, and as the Faraday element 19b, a magnetic garnet as shown in FIG. 16 is used.
- the temperature dependence of the Faraday elements 19a and 19b having a Faraday rotation angle of 45 ° at a temperature of 23 ° C. is shown in FIGS. 15 and 16, respectively.
- a Faraday element having a temperature dependency represented by the following formula 2 was obtained during reciprocation.
- the total Faraday rotation angle during magnetic saturation at a temperature of 23 ° C. when the linearly polarized light LO and LR are transmitted in a reciprocating manner is 48.14 °.
- FIG. 17 shows the temperature dependence of the total Faraday rotation angle during the reciprocation.
- Table 4 and FIG. 18 show the temperature characteristics of the ratio error in the measured value of the measured current I, which is output from the signal processing circuit of the current measuring device 20.
- the ratio error based on the temperature of 23 ° C. is within ⁇ 0.04 to 0.01%. It became possible. That is, the fluctuation range of the ratio error is in the range of 0.05% over the temperature range of ⁇ 20 ° C. to 80 ° C.
- the total Faraday rotation angle during magnetic saturation when linearly polarized light LO and LR are transmitted in a reciprocating manner is 48.44 °.
- Table 5 and FIG. 20 show temperature-ratio error characteristics in the measured value of the current I to be measured, which is output from the signal processing circuit of the current measuring apparatus 1 including the first Faraday rotator 7 as described above.
- the specific error range is ⁇ 0.05 to 0.01%, and the fluctuation range of the specific error is within the range of 0.06% over the temperature range of ⁇ 20 ° C. to 80 ° C. Become. Compared with Example 2, one Faraday rotator was able to achieve equivalent performance.
- the rotation angle of the Faraday rotator is changed from 22.5 ° to ⁇ ° at a temperature of 23 ° C., and is output from the signal processing circuit of the current measuring device.
- the fluctuation range of the ratio error in the measured value of the current to be measured is suppressed within a range of ⁇ 0.5% over the temperature range of ⁇ 20 ° C. to 80 ° C. Accordingly, the temperature characteristic of the ratio error in the measured value can be compensated by an optical system called a Faraday rotator, so that the reliability of the current measuring device is improved and the fluctuation range of the ratio error is ⁇ 0.5.
- the ratio within% it is possible to realize a current measuring device that can be applied to protective relay applications.
- the rotation angle ⁇ ° of the Faraday rotator is adjusted after adding the temperature characteristic of the specific error of the lead glass fiber.
- the optical fiber 2 for sensor may be a quartz glass fiber.
- the first optical fiber 9 may be changed to a single mode optical fiber, and the polarization separation prism 15 may be changed to a polarization dependent / independent optical circulator.
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- Measurement Of Current Or Voltage (AREA)
Abstract
Description
前記センサ用光ファイバは被測定電流が流れている導体の外周に周回設置されると共に、直線偏光を入射するための一端と、入射した前記直線偏光を反射する他端とを備え、
前記偏光分離部は、前記センサ用光ファイバの一端側に設けられると共に、
前記ファラデー回転子は、前記センサ用光ファイバの一端側と前記偏光分離部との間に配置され、
更に、
前記ファラデー回転子の磁気飽和時のファラデー回転角が、温度23℃において22.5°+α°に設定されることで、前記信号処理回路から出力される前記被測定電流の測定値における比誤差の変動幅が±0.5%の範囲内に設定されることを特徴とする電流測定装置である。
2 センサ用光ファイバ
3 光回路部
4 光電変換部
5 導体
6 反射膜
7 第1ファラデー回転子
7a、18a 永久磁石
8 偏光分離器
9 第1光ファイバ
9a 第1光ファイバの端面
9b 第1光ファイバ9の他端
10 第2光ファイバ
10a 第2光ファイバの端面
11、14 レンズ
12 フェルール
13 光源
15 偏光分離プリズム
16 第1光電変換素子
17 第2光電変換素子
18 第2ファラデー回転子
19a、19b ファラデー素子
LO、LR 直線偏光
L1 常光線
L2 異常光線
I 被測定電流
Claims (10)
- 電流測定装置は少なくとも、センサ用光ファイバと、偏光分離部と、ファラデー回転子と、光源と、光電変換素子を備える信号処理回路を含み、
前記センサ用光ファイバは被測定電流が流れている導体の外周に周回設置されると共に、直線偏光を入射するための一端と、入射した前記直線偏光を反射する他端とを備え、
前記偏光分離部は、前記センサ用光ファイバの一端側に設けられると共に、
前記ファラデー回転子は、前記センサ用光ファイバの一端側と前記偏光分離部との間に配置され、
更に、
前記ファラデー回転子の磁気飽和時のファラデー回転角が、温度23℃において22.5°+α°に設定されることで、前記信号処理回路から出力される前記被測定電流の測定値における比誤差の変動幅が±0.5%の範囲内に設定されることを特徴とする電流測定装置。 - 前記変動幅が±0.5%の範囲内に設定される温度範囲が100℃であることを特徴とする請求項1に記載の電流測定装置。
- 前記100℃の温度範囲が、-20℃以上80℃以下であることを特徴とする請求項2に記載の電流測定装置。
- 前記ファラデー回転子が、温度の変化に伴って磁気飽和時のファラデー回転角が2次曲線状に変化するファラデー回転角の温度特性を有することを特徴とする請求項1乃至3の何れかに記載の電流測定装置。
- 前記ファラデー回転子が、2つ以上のファラデー素子で構成されることを特徴とする請求項1乃至4の何れかに記載の電流測定装置。
- 前記2つ以上のファラデー素子のファラデー回転角がそれぞれ異なることを特徴とする請求項5に記載の電流測定装置。
- 前記信号処理回路から出力される前記被測定電流の測定値における比誤差の変動幅が、±0.2%の範囲内に設定されることを特徴とする請求項4乃至6の何れかに記載の電流測定装置。
- 前記変動幅が±0.2%の範囲内に設定される温度範囲が100℃であることを特徴とする請求項7に記載の電流測定装置。
- 前記100℃の温度範囲が、-20℃以上80℃以下であることを特徴とする請求項8に記載の電流測定装置。
- 前記センサ用光ファイバが鉛ガラスファイバであることを特徴とする請求項1乃至9の何れかに記載の電流測定装置。
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CA2762350A CA2762350C (en) | 2009-05-21 | 2010-05-18 | Electric current measuring apparatus |
US13/321,396 US8957667B2 (en) | 2009-05-21 | 2010-05-18 | Electric current measuring apparatus |
RU2011152197/28A RU2536334C2 (ru) | 2009-05-21 | 2010-05-18 | Устройство измерения электрического тока |
CN201080020512.4A CN102422168B (zh) | 2009-05-21 | 2010-05-18 | 电流测量装置 |
EP10777565.2A EP2434301B1 (en) | 2009-05-21 | 2010-05-18 | Electric current measuring apparatus |
HK12107977.8A HK1167462A1 (en) | 2009-05-21 | 2012-08-15 | Electric current measuring instrument |
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CA2903660C (en) | 2013-03-07 | 2021-11-09 | Adamant Co., Ltd. | Electric current measuring apparatus |
US9746500B2 (en) * | 2013-12-11 | 2017-08-29 | Eaton Corporation | Electrical current sensing apparatus |
WO2015091972A1 (en) | 2013-12-20 | 2015-06-25 | Abb Technology Ag | Fiber-optic sensor and method |
CN104820295B (zh) * | 2014-01-30 | 2020-04-28 | 奥普林克通信公司 | 无热法拉第旋转器反射镜 |
CN104880763A (zh) * | 2014-02-28 | 2015-09-02 | 苏州福瑞互感器有限公司 | 测量大电流传感器的氧化铅掺杂石英光纤的制备方法 |
EP3104183A1 (en) * | 2015-06-10 | 2016-12-14 | Lumiker Aplicaciones Tecnologicas S.L. | Current measuring equipment based on optical fiber for measuring the current circulating through a conductor and the associated method |
CN107091950B (zh) * | 2016-02-16 | 2021-01-19 | 姚晓天 | 基于光学传感原理集成了温度传感的反射式电流和磁场传感器 |
JP6726033B2 (ja) * | 2016-06-01 | 2020-07-22 | 九電テクノシステムズ株式会社 | 電流検出装置 |
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JP5756966B2 (ja) | 2015-07-29 |
EP2434301A1 (en) | 2012-03-28 |
JP2010271292A (ja) | 2010-12-02 |
RU2011152197A (ru) | 2013-06-27 |
US8957667B2 (en) | 2015-02-17 |
RU2536334C2 (ru) | 2014-12-20 |
EP2434301A4 (en) | 2017-08-30 |
CA2762350C (en) | 2017-07-04 |
HK1167462A1 (en) | 2012-11-30 |
CN102422168A (zh) | 2012-04-18 |
CA2762350A1 (en) | 2010-11-25 |
US20120091991A1 (en) | 2012-04-19 |
CN102422168B (zh) | 2014-11-12 |
EP2434301B1 (en) | 2023-06-28 |
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