JP2658542B2 - Optical current transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention uses a Faraday effect in which the direction of polarization rotates under the influence of a magnetic field to flow through glass to a high-voltage conductor such as a gas-insulated switchgear. The present invention relates to an optical current transformer used for measuring a relatively large current.

[Conventional technology]

The current can be measured by utilizing the rotation phenomenon of the polarization plane in the magnetic field, that is, the Faraday effect. The principle is that when polarized light passes through a glass exhibiting the Faraday effect (hereinafter referred to as Faraday effect glass) such as lead glass placed in a magnetic field generated by an electric current, the polarization plane has an angle θ = V The Faraday effect is obtained by detecting rotation by H · L (V: Verde constant, H: magnetic field strength in the light traveling direction, glass length in the L traveling direction) by a known method, and calculating the magnetic field strength H. It measures the current flowing near the glass.

In a usual current measurement site, a plurality of conductors are often installed, and are affected by a magnetic field due to a current other than the current of the conductor to be measured. Therefore, as a method of eliminating the effect of the current of the conductor other than the conductor to be measured, a through-hole is provided in the center of a single Faraday effect glass, and the conductor to be subjected to current measurement passes through this through-hole, An optical current transformer in which an optical path passing through the Faraday effect glass around the conductor is set is known (Japanese Patent Application Laid-Open No.
-153174).

FIG. 11 is a perspective view of a Faraday effect glass of an optical current transformer and a conductor penetrating the Faraday effect glass, showing one embodiment of the invention according to this publication. In this figure, a through-hole 11 is provided at the center of a substantially square plate-shaped Faraday effect glass 1, and the conductor 100 passes through the through-hole 11. The Faraday effect glass 1 has an input / output piece 16 at the lower right thereof for inputting and extracting light, and a linearly polarized input light 17 enters from the bottom to the top, and passes through the optical path described later to the vicinity of the periphery of the Faraday effect glass 1. The outgoing light 18 that has made one round is taken out. The illustration of a device for generating the incoming light 17 and a device for performing a process after the outgoing light 18 is omitted. Faraday effect glass 1
For example, in the upper horizontal side, a half of the thickness of the upper horizontal side is cut off at 45 degrees to form a slope 12, and these are also provided on the other three sides as described later. ing.

FIG. 12 is a projection view of the Faraday effect glass 1, and FIG.
FIG. 13 (A) is a front view as viewed from substantially the same direction as FIG. 11, and a side view thereof is shown around it based on trigonometry. That is, FIG. 12 (B) is a view of FIG. 12 (A) viewed from the right, FIG. 12 (C) is viewed from the top, FIG. 12 (D) is viewed from the left, and FIG. It is the side view seen from the bottom, respectively. As described above, each side has a slope formed by shaving half of the thickness to 45 degrees. Each of these slopes is 12th
In the figure (A), the upper side is the slope 12, the left side is the slope 13, and the lower side is the slope 1.
4. The right side is the slope 15. In these figures, the optical path is shown by a two-dot chain line, and the incoming and outgoing light and the reflection part are denoted by lowercase letters. The incoming light a is the same as the incoming light 17 in FIG. 11, and since this incoming light a enters from a position that is not on a slope,
The direction of the incident light a is perpendicular to the surface of the Faraday effect glass 1, and there is no change in the direction due to refraction, and the reflection at the boundary surface is minimized.

The incoming light a travels straight through the Faraday effect glass 1 toward the upper right apex in the figure and is reflected at a point b on the slope 12. The incident angle of light with respect to the slope 12 is 45 degrees, and the lead glass constituting the Faraday effect glass 1 has a large refractive index of about 1.8 and a small refractive index of about 1.5. The light is totally reflected. Therefore, the light hitting the point b of the slope 12 is totally reflected and its direction is bent at a right angle to change its direction in the thickness direction of the Faraday effect glass 1. This light impinges on point c of the slope 15 as shown in FIG. 12 (B) and changes its direction again to become parallel to the upper side as shown in FIGS. 12 (A) and 12 (c). Head to the top of. Thereafter, in the same manner as the upper right vertex, the point is completely reflected twice at the upper left vertex at the point d on the slope 13 and at the point e on the slope 12, and the direction is changed downward.
At point f on point 14 and point g on slope 13, the light is totally reflected, and its direction is changed to a horizontal direction toward the right direction, resulting in light emission h.

In this way, the light enters from one vertex of the Faraday effect glass 1 having a square shape, and is totally reflected twice at each vertex to change its direction at a right angle. As a result, along each side. Light is emitted from a position close to the light incident position by making one round around the periphery to make a round of the through hole 11. Since there is a relationship that the circulating integral of the magnetic field generated by the current flowing through the conductor penetrating through hole 11 matches the current flowing through the conductor irrespective of the circulating path, by making one round of the optical path as described above, The rotation angle of the polarization direction that the light receives is proportional to the current of the conductor. The reason why the light is totally reflected twice at each apex is to suppress the linearly polarized light from becoming elliptically polarized light. There is also a phenomenon that reflected light becomes elliptically polarized light. To avoid this, the polarization distortion is canceled out by performing total reflection twice in an appropriate combination, and as a result linearly polarized light remains after reflection. Is obtained. The twice total reflection at the vertex described above is employed for such a reason. In this case, elliptically polarized light is generated between the first total reflection and the second total reflection. If the polarization angle is rotated by a magnetic field during this period, the polarized light after the second total reflection does not become linearly polarized light. However, there is a problem that even if it is slight, it becomes elliptically polarized light. Therefore, for example, it is desirable that the distance between points b and c in FIG. 12 (B) be as small as possible. However, in practice, the minimum dimension of the distance is restricted in view of the setting accuracy of the optical path. Note that, depending on the device in which the optical current transformer is installed, the direction of the current of the plurality of conductors is one direction, so that the magnetic field component in the thickness direction of the Faraday effect glass 1 is so small that it can be ignored. In such a device, the phenomenon described above does not have to be a problem.

[Problems to be solved by the invention]

As is clear from the foregoing, only one end of the slope 12, 13, 14, 15 is involved in total internal reflection, and the center of the slope plays no role. Therefore, the polishing for finishing the reflection surface into a mirror surface for effectively performing the total reflection only needs to be performed at both ends of the slope. However, in an actual polishing operation, it is difficult to polish only a part of one plane, and the entire plane is necessarily polished. In addition, since there is a phenomenon that the peripheral portion of the surface to be polished is polished more than the central portion, a dummy glass, which is usually called a toy, which is aligned with the surface to be polished, is arranged around the periphery. By polishing them together, the required polished surface is uniformly polished.

As described above, in order to provide the slopes 12, 13, 14, and 15, it is necessary to polish these car surfaces over the entire surface.In addition, as described above, a toy is provided. Effect glass for an optical current transformer, the size of the through-hole 11 also increases due to the increase in the conductor cross-sectional dimension, and accordingly, the Faraday effect glass 1
Will increase in size. Therefore, four slopes
Polishing for forming 12,13,14,15 has a problem in that the polishing surface increases in proportion to the increase in the size of the Faraday effect glass, so that the time and cost required for polishing increase. Optical current transformers can be used in place of conventional instrument current transformers based on the same principles as transformers, and are effective for high voltage equipment such as gas insulated switchgear, which also have large capacities. Since the current is usually large with a large value of about 1,000 amperes, the size of the Faraday effect glass 1 needs to be large as described above. Therefore,
There is a problem that the increase in polishing time and cost due to the increase in the size of the polishing surface as described above becomes even more important. Also,
The fact that a large amount of time is required for polishing poses a problem in producing a large amount of Faraday effect glass.

An object of the present invention is to solve such a problem and to provide an optical current transformer having a Faraday effect glass which requires only a small polishing surface, reduces polishing time and cost, and is suitable for mass production. .

[Means for solving the problem]

According to the present invention, there is provided a Faraday effect glass provided with a through hole for penetrating a conductor in a central portion, and an optical path orbiting the through hole is provided in the Faraday effect glass. In the optical current transformer, a rectangular optical path surrounding the through-hole is assumed in the Faraday effect glass, and four slopes as reflecting surfaces for bending the optical path at right angles at four apexes of the assumed optical path. Is provided on the Faraday effect glass, a reflecting piece having an adhesive surface bonded to the slope is bonded to three of the slopes, and an input / output light piece formed of a right-angle prism is bonded to the remaining one slope. A reflecting surface that changes the optical path along the side of the assumed optical path in the thickness direction, and a reflecting surface that changes the optical path bent in the thickness direction parallel to the adjacent side perpendicular to the side. Horn Shall have a reflecting surface, also,
A Faraday effect glass provided with a through-hole through which a conductor penetrates at the center is provided, and in the Faraday effect glass, an optical path provided around the through-hole is provided in the Faraday effect glass. Assuming a rectangular optical path surrounding the through hole, three notches including respective vertices at three apexes of the assumed optical path and providing three notches whose cutout surfaces are orthogonal to the assumed optical path are provided. A reflective piece having two adhesive surfaces orthogonal to each other is bonded, and
A slope as a reflection surface for bending an optical path at a right angle is provided at one of the apexes, and an input / output light piece made of a right-angle prism is bonded to the slope, and the reflection piece has a thickness along the side of the assumed optical path. The light path bent in the thickness direction and a reflective surface that changes the light path in parallel with the adjacent side perpendicular to the side, In the vessel, the Faraday effect glass is made of a circular plate, or the Faraday effect glass is made of a rectangular plate, and the sides of this rectangular plate and the sides of the rectangle of the assumed optical path are parallel to each other. In this optical current transformer, the reflecting piece is made of glass made of a material different from that of the Faraday effect glass.

[Action]

In the configuration of the present invention, a rectangular optical path is assumed in the Faraday effect glass, and slopes are provided at four apexes of the assumed optical path as reflection surfaces whose optical paths are bent at right angles, and three of the slopes are provided with the slopes. A reflection piece having a bonding surface to be bonded to is bonded, and a right-angle prism is bonded to the remaining one slope as an input / output light piece.
A reflecting surface that changes the optical path along the side of the assumed optical path in the thickness direction,
By providing two reflecting surfaces, a reflecting surface that changes the optical path parallel to the adjacent side perpendicular to the above-described side, the light path changed in the thickness direction, the light that enters the input / output piece in parallel to one side. Passes through the slope at the next apex and enters the reflective piece adhered to this slope, this light is totally reflected on the reflecting surface that changes in the thickness direction of the Faraday effect glass and changes its direction in the thickness direction, This light is totally reflected by the reflecting surface which is changed parallel to the adjacent side, changed to be parallel to the adjacent piece, and heads toward the next adjacent vertex. At the next vertex in the same manner, and at the next vertex, the reflection piece makes a total reflection that bends twice at right angles in the reflection piece, and consequently makes a round around the through hole through which the current flowing conductor passes. Light exits the Faraday effect glass through the input and output pieces. 2 at each of the three vertices
The reflection piece to be reflected twice can be manufactured separately from the Faraday effect glass, and its size and shape can be set regardless of the size of the Faraday effect glass. The reflecting pieces can have the same dimensions and shape. In addition, the slope of the Faraday effect glass and the reflecting surface of the reflecting piece need to be polished and mirror-finished in order to totally reflect, but the limited small surface becomes the polished surface, so the time and cost required for polishing Is small.

In addition, three of the assumed optical paths provided in the Faraday effect glass
One vertex is cut out at a right angle, a reflective piece having two adhesive surfaces orthogonal to each other is bonded to this notch, and the other one vertex is provided with a slope similar to the above-mentioned slope to enter and exit a right-angle prism. A piece is adhered, and the reflecting piece is a reflecting surface that changes the optical path along the side of the assumed optical path in the thickness direction, and the optical path changed in the thickness direction is an optical path parallel to the adjacent side perpendicular to the side. By providing two reflecting surfaces, a changing reflecting surface, the light entering through the input and output pieces is totally reflected twice in each of the reflecting pieces in the same manner as in the case where the slope is provided at the apex described above. Then, the light travels around the periphery of the Faraday effect glass and emits light from the input and output pieces. Since the dimensions of the notch and the reflective piece cut out at a right angle can be set independently of the size of the Faraday effect glass, the reflective piece can be standardized as in the case described above. In addition, since this reflecting piece can be formed by bringing two right-angle prisms into close contact with each other, the price of the optical current transformer can be reduced by using a commercially available right-angle prism.

The Faraday effect glass may be of any shape as long as a rectangular hypothetical optical path can be set therein and a rectangular cutout with a slope at the apex can be provided.

If a circular plate is used for the Faraday effect glass, a relatively small amount of polishing is required when providing a slope or a notch. In addition, if the shape of the Faraday effect glass is a rectangular plate shape including a square, the assumed optical path of the rectangle can be set efficiently according to the shape of the Faraday effect glass, so that the material usage of the Faraday effect glass is small. Yes.

In any of the above-described two types of optical current transformers having different configurations in which the shape of the notch and the reflective piece adhered to the cutout portion are different, the material of the reflective piece may be different from the material of the Faraday effect glass. it can. In this case, it is ideal that the respective materials have the same refractive index, and a material having a small Verdet constant that determines the strength of the Faraday effect of the reflecting piece is desirable. Especially when a notch with a special angle is provided, the bonding surface of the reflection piece and the Faraday effect glass are all orthogonal to the optical path, so even if the refractive indexes of both are different, the direction of the optical path by refraction does not change, so the difference in the refractive index The effect is small.
Therefore, it is easy to employ a commercially available right-angle prism with a small Verdet constant.

〔Example〕

Hereinafter, the present invention will be described based on examples. FIG. 1 is a perspective view of a Faraday effect glass showing a first embodiment of the present invention. In this figure, a square-shaped Faraday effect glass 2 having a through-hole 21 in the center has four apexes cut out at 45 degrees, and slopes 22, 23,
24,25 are formed. The slope 22 has a reflective piece 26 described later.
However, a reflection piece 27 is bonded to the slope 23, a reflection piece 28 is bonded to the slope 24, and an input / output piece 29 is bonded to the slope 25. In this figure, the reflection pieces 26, 27, 28 and the input / output pieces 29 all show a state before bonding. The reflecting pieces 26 and 28 have the same dimensions and shape, and the reflecting piece 27 has a plane symmetrical shape with respect to them. The input / output piece 29 is formed of a right-angle prism.

FIG. 2 is a projection view illustrating an optical path passing through the Faraday effect glass 2 and the reflection pieces 26, 27, 28 and the input / output piece 29 adhered to the Faraday effect glass 2 as in FIG. FIG. 2 (A), which is a front view, and four side views are arranged therearound. The relationship between these figures is the same as FIG. 12, and a description thereof will be omitted. The incoming light a enters the Faraday effect glass 2 via the incoming / outgoing piece 29, is totally reflected twice by the reflecting piece 26 attached to the slope 22, changes its direction to the horizontal direction, and goes to the slope 23. The reflection piece 27 on the slope 23 and the reflection piece 28 on the slope 24 are both 2 pieces.
As a result of the total reflection, the direction of the optical path is changed, and as a result, the emitted light h is emitted through the input / output piece 29.

FIG. 3 is a projection view showing only the reflection piece 26 of FIG. 2 and showing the optical path and the state of reflection, and the reference numerals of the three figures correspond to those of FIG. Adhesive surface 26
Reference numeral 3 denotes a surface adhered to the inclined surface of the Faraday effect glass 2, and a reflection surface 261 for incoming light a that has entered from this surface.
Has an angle of 45 degrees, the light is totally reflected at point b on the reflecting surface 261 and the point c of the reflecting surface 262 having an angle of 45 degrees in the direction of the light after being bent at a right angle is again The light is reflected and bent at a right angle, and as a result, the direction of the outgoing light d in FIG. Such an optical path is basically the same as the Faraday effect glass 1 of the conventional optical current transformer shown in FIG.

The three surfaces of the reflective piece 26 that require polishing are the reflective surfaces 261, 262 and the adhesive surface 263. The surface of the Faraday effect glass 2 that requires polishing is the four slopes 22, 23, 24, 25.
It is. The dimensions of these four slopes 22, 23, 24, 25 are irrelevant to the vertical and horizontal dimensions of the Faraday effect glass 2, and the dimensions of the Faraday effect glass 2 increase, and the dimensions of the polished surface remain unchanged. In addition, since the reflection pieces 26, 27, 28 and the input / output piece 29 need not be related to the dimensions of the Faraday effect glass 2, the dimensions and materials of the reflection pieces are standardized, the same size and shape are produced in large quantities, and the price due to the quantity effect is reduced. Reduction is possible. In addition, the polished surface may be a limited small surface including the Faraday effect glass 2, so that the number of surfaces requiring polishing as the entire optical current transformer increases, but the total polished area decreases.
Polishing time in fabricating two optical current transformers is also reduced. The required minimum dimensions of the slopes 22, 23, 24, 25 and the reflecting pieces 26, 27, 28 of the Faraday effect glass 2 are related to the accuracy of the optical path. As long as it does not come off the reflective surfaces of the reflective pieces 26, 27, and 28.
Since the dimensions of 26, 27, and 28 and the slopes 22, 23, 24, and 25 can be reduced, the cost of the optical current transformer can be expected to be reduced by reducing these dimensions with the improvement of the optical path setting technology.

The material of the reflection pieces 26, 27, 28 is generally the same as that of the Faraday effect glass 2. On the other hand, the bonding surface between the Faraday effect glass 2 and the reflection pieces 26, 27, 28
Since it has an angle of 45 degrees, if the refractive index is different, refraction occurs at the bonding surface, and the optical path is changed, so that it is difficult to set an accurate optical path. Therefore, the material of the reflection pieces 26, 27, and 28 is optimally a glass having substantially the same refractive index as the material of the Faraday effect glass 2 and a small Verdet constant. The refractive index of the lead glass generally used for the Faraday effect glass 2 and the glass other than the lead glass having a small Verdet constant have various values. It is possible to select a material which is the above-mentioned optimal combination within a range having a necessary value of the refractive index.

FIG. 4 is a perspective view of a Faraday effect glass showing a second embodiment of the present invention.
29 is the same as that of FIG. 1, and the description is omitted. Slope 25
The three vertices except for the lower right vertex provided with are formed with notches 32, 33, and 34 to form notches 32, 33, and 34. Reflecting pieces 36, 37 are formed in these notches 32, 33, and 34, respectively. , 38 are mounted respectively. This figure shows a state before mounting. The reflecting pieces 36, 37, 38 have a shape obtained by combining two right-angle prisms as described later.

5 and 4, Faraday effect glass 3 and reflector 3
FIG. 6 is a projection view showing optical paths at 6, 37, 38, etc., and the five figures have the same relationship as FIG. The notch 32 is cut out so as to form a square in consideration of symmetry, and is mounted so that a reflective piece 36 fits in the inner corner thereof, and the notch 32 is connected to the Faraday effect glass 3 via the adhesive surface. Light enters and exits from the piece 36. This case is also similar to the case of FIG. 2 in the first embodiment, in which light a enters through the input / output piece 29 and is reflected twice by the reflection pieces 36, 37, and 38, respectively. As a result, after making a round around the through hole 21, the light is emitted to the outside through the input / output piece 29 as the light emitting hole h.

FIG. 6 is a projection view showing only the reflection piece 36 of FIGS. 4 and 5 and showing the optical path and the state of reflection thereof. The reference numerals of the three figures are the same as those of FIG.
The reflection piece 36 has a shape in which two right-angle prisms 365 and 366 are adhered to each other.
4 is glued. The reflecting surface 361 is at an angle of 45 degrees with respect to the incident light a from the Faraday effect glass 3, and the incident light a is totally reflected at a point b of the reflecting surface 361, and the direction is bent at a right angle and bent. The light is totally reflected once again at point c of the reflecting surface 362 having an angle of 45 degrees with respect to the light in the direction, and changes its direction again to a right angle, and returns to the Faraday effect glass 3 as light emission d in this figure.

The four surfaces of the reflective piece 36 that require polishing are the reflective surfaces 361 and 362 and the adhesive surfaces 363 and 364. Also, two right angle prisms 3
When the reflection pieces 36 are manufactured by separately manufacturing and bonding the 645 and 366, it is necessary to polish the bonding surface. Adopting a method of manufacturing a reflecting piece by bonding a right-angle prism has the advantage that an inexpensive commercially-available right-angle prism can be used. In this case, the Faraday effect glass 3 and the reflection piece 36
If the refractive indices of the materials are different, some light is reflected on the bonding surface, but since the angle between the bonding surface and the light is a right angle, no refractive index occurs. Therefore, in this embodiment, if the material has a similar refractive index, the Faraday effect glass 3
It is possible to use the reflecting pieces 36, 37, 38 made of a material different from the above, and it is possible to enhance the effect by using a commercially available one as described above.

In the above-mentioned Faraday effect glasses 2 and 3, the through-hole is circular and the shape of the Faraday effect glass is accordingly square, but the shape of the conductor penetrating the through-hole is not necessarily cylindrical and the cross-section is not limited to a cylinder. May be a square flat bar. On the other hand, the space for installing the optical current transformer is not always sufficient for all types of equipment, and is usually restricted to the minimum necessary. The through hole has a long shape on one side, and accordingly, the Faraday effect glass also has a rectangular shape. In the case where the shape of the Faraday effect glass is rectangular as described above, the shapes of the cutouts and the reflection pieces at the vertices may be the same, except that the distance at which light passes from one vertex to the next is different. Is not a restriction in applying. The only difference is that when the Faraday effect glass is rectangular, the length of the side is longer, and the effect of the present invention is greater.

FIG. 7 is a perspective view showing a third embodiment of the present invention, and members common to those in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted. The difference between FIG. 7 and FIG. 1 is that the Faraday effect glass 4 is desired to have a disk shape. The optical path indicated by the two-dot chain line and lowercase letters in FIG. 2 is originally determined by the reflection pieces 26, 27, 28 and the input / output piece 29, and the shape of the Faraday effect glass 4 does not affect unless the optical path is disturbed. It may be disc-shaped. The disc shape has the advantage that the amount of polishing of the slopes 42, 43, 44, 45 is reduced.

FIG. 8 is a perspective view showing a fourth embodiment of the present invention, and shows that the Faraday effect glass 5 may be a plate of any shape.

FIG. 9 is a perspective view showing a fifth embodiment of the present invention, and members common to those in FIG. 4 are denoted by the same reference numerals and are not described in detail. The difference between FIG. 9 and FIG. 4 is that the shape of the Faraday effect glass 6 is formed in a disk shape as in FIG. The optical path indicated by the two-dot chain line and lowercase letters in FIG. 5 is originally determined by the reflection pieces 36, 373, 38 and the input / output pieces 29. As in FIG. 7, the Faraday effect glass 6 has the same shape as long as the optical path is not obstructed. Since there is no influence, a disk shape may be used.

FIG. 10 is a perspective view showing a sixth embodiment of the present invention. In the case of an optical current transformer having a cutout as in FIG. 8, the Faraday effect glass 7 may be a plate of any shape. It shows.

In addition, although the shape of the Faraday effect glass is illustrated as a plate having a constant thickness, the thickness does not need to be constant, and may be any size as long as it is equal to or greater than the size of the reflection piece or the input / output piece. The dimensions may change depending on the position.

〔The invention's effect〕

As described above, the present invention assumes a rectangular optical path in the Faraday effect glass, and provides four vertices of the assumed optical path with a slope as a reflection surface whose optical path is bent at a right angle. The reflecting piece is adhered, and a right-angle prism is adhered to the remaining one inclined surface as an incoming / outgoing light piece. The above-described reflecting piece changes the optical path along the side of the assumed optical path in the thickness direction, and the reflecting surface in this thickness direction By providing two reflecting surfaces, a reflecting surface that changes the optical path in parallel with the adjacent side perpendicular to the above-mentioned side, the light that has entered from the input / output piece in parallel to one side of the assumed optical path is After passing through the slope at the next vertex, the light enters the reflective piece bonded to this slope, and this light changes its direction in the thickness direction of the Faraday effect glass. , This light is parallel to the next piece It changed in parallel at one of the next to the total reflection when the reflection surface is varied toward the direction of the apex of the next neighbor. In the same manner, at the next apex, at the next apex, the reflection piece makes a total reflection that bends twice at right angles in the reflection piece, and consequently makes a round around the through hole through which the conductor through which the current flows passes. Light exits the Faraday effect glass through the input and output pieces. The slope of the Faraday effect glass and the reflective surface of the reflective piece need to be polished and mirror-finished, but all are limited but polished, so the time and cost required for polishing can be reduced. Can be Also,
The reflecting pieces that are reflected twice at each of the three vertices can be manufactured separately from the Faraday effect glass, and the size and shape thereof can be set irrespective of the size of the Faraday effect glass. The same size and shape can be standardized for the effect glass.
Therefore, since a large number of reflective pieces having the same size and shape can be manufactured, the cost can be reduced based on the quantity effect. Furthermore, if the dimensional accuracy of the optical path is improved, the dimensions of the notch and the reflective piece can be reduced, so that these dimensions are reduced with the improvement of the optical path setting accuracy, thereby reducing the polishing area and the amount of material used. Become possible.

In addition, three of the assumed optical paths provided in the Faraday effect glass
One of the vertices is cut out at a right angle, and this cutout is bonded to a reflective piece having two bonding surfaces orthogonal to each other, and the other one of the vertices is provided with a slope similar to the above-described slope, so that a rectangular prism enters and exits. A piece is adhered, and the reflective piece changes the light path along the side of the assumed optical path in the thickness direction, and the light path changed in the thickness direction changes the light path parallel to the adjacent side perpendicular to this side. By providing two reflecting surfaces, a reflecting surface and light entering through the input and output pieces are totally reflected twice in each of the reflecting pieces in the same manner as in the case where the slope is provided at the vertex. After that, it goes around the periphery of the Faraday effect glass and emits light from the input and output pieces. Since the dimensions of the notch and the reflective piece cut out at a right angle can be set independently of the size of the Faraday effect glass, the reflective piece can be standardized as in the case described above. Thus, as in the case of the Faraday effect glass forming the above-described slope, the effect of reducing the polishing area, standardizing the reflector, and reducing the price of the optical current transformer based on the improvement of the optical path setting accuracy can be obtained. Further, since the reflecting piece has a shape in which two right-angle prisms are combined, the reflecting piece can be manufactured by actually bonding two commercially-available right-angle prisms, thereby further reducing the cost. Is obtained.

The Faraday effect glass may be of any shape as long as a rectangular hypothetical optical path can be set therein and a slope can be provided at the apex or a rectangular cutout can be provided. The use of a disk-shaped Faraday effect glass has the advantage that a relatively small amount of polishing is required when providing a slope or a notch. Further, by setting the sides of the assumed optical path so that the shape of the Faraday effect glass is a rectangular plate including a square and being parallel to the sides, the amount of material used for the Faraday effect glass can be minimized. Therefore, the weight of the optical current transformer can be minimized.

In any case of the optical current transformer having the Faraday effect glass having the above-described different configuration, the material of the reflection piece can be different from the material of the Faraday effect glass.
In this case, it is ideal that the respective materials have the same refractive index, and a material having a small Verdet constant that determines the strength of the Faraday effect of the reflecting piece is desirable. In particular, when a right-angled notch is provided, the bonding surfaces of the reflective piece and the Faraday effect glass are all orthogonal to the optical path, so that even if the refractive indexes of both are different, the optical path does not change due to refraction, so the difference in the refractive index The effect is small. Therefore, an effect is obtained that the Verdet constant is small and that it is easy to adopt a commercially available right-angle prism.

[Brief description of the drawings]

FIG. 1 is a perspective view of the Faraday effect glass showing the embodiment of FIG. 1 of the present invention, FIG. 2 is a projection view showing the Faraday effect glass of FIG. 1 and its optical path, and FIG. FIG. 4 is a projection view showing only two reflection pieces, FIG. 4 is a perspective view of a Faraday effect glass showing a second embodiment of the present invention,
FIG. 5 is a projection view showing the Faraday effect glass of FIG. 4 and its optical path, FIG. 6 is a projection view showing only one reflecting piece of FIG. 5, and FIG. 7 is a third embodiment of the present invention. 8 is a perspective view of a Faraday effect glass showing a fourth embodiment of the present invention, and FIG. 9 is a perspective view of a Faraday effect glass showing a fifth embodiment of the present invention. FIG. 10 is a perspective view of a Faraday effect glass showing a sixth embodiment of the present invention, FIG. 11 is a perspective view of a Faraday effect glass of a conventional optical current transformer and a conductor penetrating the same, FIG. 12 is a projection view showing the Faraday effect glass of FIG. 11 and its optical path. 1,2,3,4,5,6,7 …… Faraday effect glass, 11,21,31,41,51,61,71 …… Through hole, 100 …… Through conductor, 12,13,14,15 , 22,23,24,25,42,43,44,45,52,53,54,55…
… Slope, 26,27,28,36,37,38… Reflection piece, 29 …… In / out piece, 32,33,34,62,63,64,72,73,73 …… Notch, 261,262,361,362 …… Reflective surface, 263,363,364 …… Adhesive surface, 365,366 …… Right angle prism.

Claims (5)

(57) [Claims] 1. An optical current transformer comprising a Faraday effect glass provided with a through hole through which a conductor penetrates in a central portion, and an optical path surrounding the through hole provided in the Faraday effect glass. Assuming a rectangular optical path surrounding the through hole in the Faraday effect glass, the Faraday effect glass is provided with four inclined surfaces at four apexes of the assumed optical path as reflecting surfaces for bending the optical path at right angles, 3 of this slope
A reflecting piece having an adhesive surface bonded to the slope is bonded to the other, and an incoming / outgoing light piece formed of a right-angle prism is bonded to the remaining one slope, and the reflecting piece forms an optical path along the side of the assumed optical path. An optical current transformer comprising two reflecting surfaces, a reflecting surface changing in a thickness direction and a reflecting surface changing an optical path parallel to an adjacent side perpendicular to the side, the optical path bent in the thickness direction. . 2. An optical current transformer comprising a Faraday effect glass provided with a through hole through which a conductor penetrates at a central portion, and an optical path surrounding the through hole provided in the Faraday effect glass. In the Faraday effect glass, a rectangular optical path surrounding the through hole is assumed, and three notches including respective vertices at three apexes of the assumed optical path and having cutout surfaces orthogonal to the assumed optical path are provided. Reflecting pieces having two adhesive surfaces orthogonal to each other are adhered to these cutouts, and a slope as a reflection surface for bending an optical path at a right angle is provided at the remaining one apex portion. A reflective surface that changes an optical path along a side of the assumed optical path in a thickness direction, and an optical path bent in the thickness direction in an optical path parallel to an adjacent side perpendicular to the side. change An optical current transformer having two reflecting surfaces, a reflecting surface and a reflecting surface. 3. The optical current transformer according to claim 1, wherein the Faraday effect glass is a circular plate. 4. The optical current transformer according to claim 1, wherein the Faraday effect glass is formed of a rectangular plate, and a side of the rectangular plate and a side of the rectangle of the assumed optical path are parallel to each other. 5. The optical current transformer according to claim 1, wherein the reflection piece is made of a glass different from that of the Faraday effect glass.