JP6633356B2 - Insulator type optical current transformer - Google Patents

Description

  Embodiments of the present invention relate to an insulator type optical current transformer.

  As an instrument for measuring a current flowing through a high-voltage conductor, for example, an insulator type current transformer using oil or SF6 gas as an insulating material is generally used.

  Recently, a photocurrent sensor using the Faraday effect is small and lightweight, and an optical current transformer using the photocurrent sensor has been commercialized.

  In this type of optical current transformer, signals are transmitted using an optical fiber line. However, since glass, which is a member of the optical fiber line, is an insulating material, it is easy to secure insulation, and a photocurrent with a built-in Faraday element is used. It is possible to install the sensor in the high-voltage section where the conductor is arranged.

  On the other hand, the optical fiber wire is easily broken when an excessive force is applied because the glass material is thinly stretched. Therefore, sufficient care must be taken when handling the optical fiber wire.

  In particular, in an electric system to which an earthquake or a high-voltage conductor is connected, an electromagnetic force caused by a large current generated during an accident such as a short circuit causes the insulator tube to vibrate or deform, and apply excessive force to the optical fiber line or bend the optical fiber line. This causes breakage of the optical fiber line and loss of light amount.

  If the optical fiber wires are not fixed, the optical fiber wires are entangled with each other. Therefore, an optical fiber built-in insulator having a structure in which the optical fiber wire is buried and passed through the inner wall of the insulator tube has been developed.

JP-A-06-325648

  In the case of the insulator (insulator tube) described in the above-mentioned document, the light amount loss is not caused by the helical arrangement of the optical fiber line along the side surface of the insulator tube or the stress due to bending in order to prevent the breakage of the optical fiber line due to bending. There is a problem that the production becomes complicated and expensive, such as injecting silicone grease into the inside of the insulator tube. In addition, when the voltage of a conductor through which a current flows becomes higher, the size of the insulator tube becomes large and long, and there are also problems such as difficulty in manufacturing and increase in cost.

  An object of the present invention is to provide an insulator type optical current transformer which is easy to assemble, inexpensive and highly reliable.

  The insulator type optical current transformer according to the embodiment has a first metal container, a second metal container, and a hollow insulator tube. The first metal container houses a metal conductor through which a current flows and a photocurrent sensor that measures the current flowing through the metal conductor and converts the current into an optical signal, and a lower portion of the container for transmitting an optical signal extracted from the photocurrent sensor. A first hole for inserting the optical fiber line is provided. The second metal container is provided at the grounding portion, and a second hole for inserting an optical fiber line is provided at an upper portion of the container so as to face the first hole. The porcelain tube has a first metal container arranged above and a second metal container arranged below, and is arranged so as to connect between the metal containers. The optical fiber line is drawn from the photocurrent sensor, inserted through the first hole of the first metal container and the second hole of the second metal container, and disposed so as to hang straight down substantially in the center of the insulator tube. Have been.

1 is an overall configuration diagram of an insulator type optical current transformer according to a first embodiment of the present invention. FIG. 2 is a detailed view of a high-voltage section of FIG. 1. FIG. 2 is a detailed view of a ground potential unit in FIG. 1. FIG. 2 is a detailed view of a potential fixing member (high-voltage section side) in FIG. 1. FIG. 2 is a detailed view of a positioning structure of an optical fiber core wire on a ground potential portion side in FIG. 1. FIG. 6 is a perspective view of FIG. 5. FIG. 2 is a detailed view of a potential fixing member (ground potential portion side) in FIG. 1. FIG. 8 is a perspective view of FIG. 7. It is a figure showing the relation between the electric potential of the insulator type current transformer, and the length of the optical fiber core wire.

Hereinafter, an insulator type optical current transformer according to one embodiment will be described with reference to the drawings.
As shown in FIG. 1, the insulator type optical current transformer of this embodiment includes a metal container 2 as a first metal container disposed on the high voltage portion side (upper side) and a ground potential portion side (lower side). A) a metal container 5 serving as a second metal container disposed in the above-described manner, and a hollow insulator tube 4 disposed (erected) with the axis set in a vertical direction so as to connect the metal containers 2 and 5 to each other. An optical fiber core wire 6 as an optical fiber wire disposed so as to hang straight down substantially in the center of the insulator tube 4.

  The insulator tube 4 has the metal container 2 disposed above and the metal container 5 disposed below, and is disposed so as to connect between the metal containers 2 and 5.

  The inside of the metal containers 2, 5 and the insulator tube 4 is not filled with silicone grease or the like, and is filled with a gas (insulating gas) such as SF6 gas, nitrogen gas, dry air, air, or the like as necessary. In this example, the metal containers 2 and 5 and the insulator tube 4 are filled with SF6 gas.

  As shown in FIG. 2, the metal container 2 has an opening at the bottom surface, and the container lower plate 2a is attached to the opening and is sealed. The container lower plate 2a is provided with a hole 11 as a first hole for inserting the optical fiber core wire 6 into the insulator tube 4 side.

  The inner peripheral surface of the hole 11 has a surface roughness such as finer than 25S (JIS standard) so that the optical fiber core wire 6 can move smoothly. In addition to simply providing the hole 11 in the container lower plate 2a, an insulating material having good slidability, for example, an annular member (O-ring) made of a fluororesin may be provided at the edge of the hole 11.

  Note that 25S (JIS standard) is a roughness classification of “25S” in “Surface roughness classification” of JIS B 0601: 1990 Rmax, and roughness finer than 25S (JIS standard) is, for example, “12. 5S "," 6.3S "," 3.2S "," 1.6S "," 0.8S ", etc. "12.5S" is an intermediate-grade machined surface, and refers to a surface obtained by turning, milling, or the like, which can be obtained at a high speed with an appropriate feed and a good tool.

  "6.3S" is a good machined surface, and refers to the outer surface of the outer race of the rolling bearing, the surface where the valve and the valve seat are bonded, and the outer surface of the hydraulic cylinder / ram. The same effect can be obtained by forming the member (in this case, the container lower plate 2a) in which the hole 11 is provided or a portion around the hole 11 with an insulating material such as a fluororesin instead of metal.

  The metal container 2 houses a conductor 1 as a metal conductor through which a current flows, a photocurrent sensor 3 for measuring a current flowing through the conductor 1, and a potential fixing member 12 as a first potential fixing member.

  The photocurrent sensor 3 is a sensor that measures a current flowing through the conductor 1 using the Faraday effect and converts the current into an optical signal, and is provided with at least one or more. In the case of this example, three photocurrent sensors 3 are provided for the main system, the sub system, and the standby system.

  For this reason, a plurality of holes 11 (see FIG. 3) and a plurality of holes 21 (see FIG. 5) are arranged at predetermined intervals near the axis of the insulator tube 4 so as to pass through the optical fiber core wires 6 for a plurality of systems. .

  An optical fiber core 6 is drawn out of the optical current sensor 3, and an optical signal, which is a measurement result of a current, is transmitted by the optical fiber core 6.

  After the three optical fiber core wires 6 pulled out from each photocurrent sensor 3 are fixed (adhered) to the potential fixing member 12, they are inserted into the holes 11 of the container lower plate 2 a of the metal container 2, and Is inserted through a hole 21 of a core positioning member 9 fixed to a lid 8 (container upper plate) attached so as to hang down linearly at a substantially central portion of the metal container 5 so as to close the opening 7 on the upper part of the metal container 5 (see FIG. 2 and 4).

  That is, the optical fiber core wire 6 for transmitting a signal is connected to the photocurrent sensor 3 disposed in the metal container 2 in the high voltage portion, passes near the center of the insulator tube 4, and is disposed in the ground potential portion. 5 is wired.

  As shown in FIG. 3, the potential fixing member 12 is a metal ring-shaped member having a slope 12a inclined so as to descend inward, and has a central portion opened so that the hole 11 of the container lower plate 2a is exposed. Have been. Since the potential fixing member 12 is made of metal, it has the same potential as the high voltage portion.

  The three optical fiber core wires 6 are respectively adhered and fixed to the inclined surface 12a of the potential fixing member 12 with the silicone adhesive 13, and then inserted into the holes 11 provided in the container lower plate 2a.

  As shown in FIG. 4, inside the metal container 5, a lid 8 is disposed so as to close an opening 7 provided at an upper portion (upper surface) of the metal container 5, and provided at a substantially central portion of the lid 8. An opening 8a (see FIG. 6) and a potential fixing member 22 as a second potential fixing member fixed to the lower surface of the lid 8 avoiding the opening 8a are accommodated.

  In the metal container 5, the optical fiber core wire 6 inserted into the metal container 5 through the insulator tube 4 is provided with a slack 6 a (excess length portion) and fixed (fixed) to the potential fixing member 22 with the silicone adhesive 13, The fiber core wire 6 is wired downward. Since the silicone adhesive 13 has a low hardness even after curing, the silicone adhesive 13 can flexibly cope with the movement and expansion / contraction of the optical fiber core wire 6.

  On the upper surface of the metal container 5 connected to the insulator tube 4, a hole 21 is provided at a position almost directly below the upper hole 11. That is, on the upper surface of the metal container 5, a hole 21 for inserting the optical fiber core wire 6 into the upper portion of the container is provided so as to face the hole 11.

  The optical fiber core wire 6 enters the metal container 5 from the insulator tube 4 through the hole 21. At this time, the same number of holes 11 and holes 21 as the number of the optical fiber core wires 6 are prepared, and one pair (a pair) is formed vertically, and one optical fiber core wire 6 is passed through one set (a pair). In other words, a plurality of optical fiber core wires 6 do not pass through one set of holes.

  The surface of the hole 21 on the side of the ground voltage portion has a surface roughness finer than 25S (JIS standard) so that the optical fiber core wire can move smoothly. As a constituent member of the hole 21 on the upper surface of the metal container 5, an insulating material such as an annular member (O-ring) made of a fluororesin having good slidability similarly to the above-described high voltage portion may be used.

  In this embodiment, a core wire positioning member 9 made of fluororesin is provided near the center of the upper surface of the metal container 5 as a member for providing the hole 21.

  As shown in FIGS. 5 and 6, a positioning structure for positioning the optical fiber core wire 6 is formed on the upper portion of the metal container 5 by a lid 8, a core wire positioning member 9, a pressing member 10, a screw 31, and the like.

  The core wire positioning member 9 is a disk-shaped member, and is provided with three holes 21 for inserting the optical fiber core wire 6 near the center and four screw holes 9a for screwing. The holding member 10 is a ring-shaped member and has a screw hole 31 corresponding to the screw hole 9a. The pressing member 10 is fixed by sandwiching the core wire positioning member 9 between the pressing member 10 and the cover 8 and screwing the screws 31 from the back surface of the cover 8 into the screw holes 9 a and the screw holes 31.

  As shown in FIGS. 7 and 8, the potential fixing member 22 has a half-cylindrical shape (shape like a rain gutter) obtained by vertically dividing a metal tube into two, and is fixed to the lower surface of the lid 8 with screws or the like. ing.

  The metal container 5 is provided with an opening 7 at the top. A lid 8 is attached to the upper part of the metal container 5 so as to close the opening 7. The cover 8 is provided with a hole at a substantially central portion, and a core wire positioning member 9 is attached to this hole.

  The core positioning member 9 has a hole 21 as a second hole for inserting the optical fiber core 6. That is, the metal container 5 is provided with a hole 21 for inserting the optical fiber core wire 6 in the upper part of the container, facing the hole 11 of the upper metal container 2.

  The holes 11 and 21 are arranged so as to be scattered at a position apart from the center of the insulator tube 4 by a predetermined distance. As a specific example, three are provided at intervals of 120 degrees.

  Inside the metal container 5, the optical fiber core wire 6 is wired with a certain slack 6a (excess length). Further, a metal potential fixing member 22 having the same potential as the ground potential portion is disposed inside the metal container 5 in the hole 11. The optical fiber core wire 6 is bonded and fixed to the potential fixing member 22 so as to have the same electric potential. As an adhesive for bonding the optical fiber core wire 6, a silicone adhesive 13 which is a silicone-based adhesive having a low hardness even after curing is used.

  As the slack amount prepared inside the metal container 5 from the hole 21, a limit value A is obtained by the following (Equation 1), and at least the slack amount is made longer than the limit value A. That is, the limit value A is set to be smaller than the slack amount.

A = √ (L ² + δ ² ) -L (Equation 1)
δ = F · L ³ / (3 · E · I)
Where L is the length of the insulator tube
F: Concentrated load acting on the insulator head
E: Young's modulus of insulator tube
I: Second moment of area of insulator tube
δ: Displacement of insulator head
A: Amount of sag

  The following numerical values are obtained by calculation when a composite insulator having a cylinder length of about 4.5 m is used as the insulator 4.

  When a force acts on the head of the insulator tube 4 such as an electromagnetic force when an earthquake current or an accident current flows, the head is displaced and at the same time, a stress is generated at a connection portion between the insulator tube 4 and the metal container 5. Is designed and manufactured to withstand these mechanical stresses, but has an allowable value (generally the manufacturer's guaranteed value), and this force is F (concentrated load acting on the insulator head). And

As a result, A = 7.88 × 10 ⁻³ [m].
Therefore, the slack amount A is set to 8 mm or more.

The insulator-type optical current transformer configured as described above operates as follows.
Since the hole 21 for passing the optical fiber core 6 on the upper surface of the metal container 5 is provided directly below the hole 11 for passing the optical fiber core 6 on the bottom surface of the metal container 2, the optical fiber core 6 is linearly provided. Can be. Therefore, the optical fiber core wire can be easily arranged, and a complicated manufacturing process is not required, and the manufacturing cost can be reduced.

  In addition, silicone grease or the like is not injected into the inside of the insulator tube 4 and the metal container 5, and the periphery of the optical fiber core wire 6 in the insulator tube 4 becomes gas. Accordingly, since there is no action of force and no generation of stress due to the contact of the optical fiber core wire 6 with the surrounding member, stable quality can be secured. Naturally, injection of silicone grease or the like is not performed. Therefore, the manufacturing process is simplified, and the cost can be reduced.

  Further, only one optical fiber core wire 6 is provided for one set of the holes 11 and 21 for the wire. Therefore, the adjacent optical fiber core wires 6 do not become entangled with each other, and there is no breakage due to the optical fiber core wires 6 touching each other.

  When an earthquake or an accident occurs, the head of the insulator tube 4 is displaced by the seismic force or electromagnetic force, and a necessary amount of the optical fiber core wire 6 is drawn into the insulator tube 4 from the slack 6a according to the displacement.

  On the other hand, by securing the slack 6a of the optical fiber core 6 not less than the minimum necessary length defined by (Equation 1), it is possible to prevent the optical fiber core 6 from being broken without excessive force being applied to the optical fiber core 6. Absent.

  Also, when the head of the insulator tube 4 is displaced, the optical fiber core wire 6 rubs with the holes 11 and 21 inserted therein, but the surface roughness of the holes 11 and 21 is finished with a roughness finer than 25S (JIS standard). The smoothness prevents the surface of the optical fiber core wire 6 from being damaged or broken.

  Here, with reference to FIG. 9, the relationship between the potential and the length of the optical fiber core wire 6 when the insulator type optical current transformer is used in a system having a high DC voltage such as DC power transmission will be described.

  When an insulator type optical current transformer is used in a system where DC voltage is high, the potential is determined by the resistance value because the optical fiber core wire 6 is an insulator. The resistivity of the optical fiber core 6 is uniform, L: the length of the optical fiber core 6 between two points at which the potential is fixed, V1: the potential at the position of the hole 11 of the metal container 2 of the optical fiber core 6, V2: electric potential of the optical fiber core 6 at the position of the hole 21 of the metal container 5, L1: length of the optical fiber core 6 from the photocurrent sensor 3 to the position of the hole 11 of the metal container 2, L2: of the metal container 5 Assuming that the length of the optical fiber core wire 6 from the position of the hole 21 to the ground potential point,

V1 = (L−L1) × V / L
V2 = L2 × V / L
Where L = 4.5 m L1 = 0.2 m L2 = 0.3 m V = 250 kV
Substituting
V1 = 239 kV
V2 = 17 kV
Becomes

  Normally, the potential of the optical fiber core wire 6 at the edge of the hole 11 of the metal container 2 is 239 kV, and the potential of the metal container lower plate 2a itself provided with the hole 11 is 250 kV, and a difference voltage of 11 kV is generated.

  In the wiring condition of the optical fiber core wire 6, although the optical fiber core wire 6 approaches the hole 11, a state like a minute gap that does not contact the metal container lower plate 2 a itself continues, and the optical fiber core 6 is partially discharged or dielectrically broken down. The core wire 6 may be damaged or broken.

  Therefore, in this embodiment, a potential fixing member 12 having the same potential as the metal container 2 is disposed near (upper) the hole 11, and the optical fiber core wire 6 is forcibly brought into contact with the potential fixing member 12 by being bonded thereto. Have an electrical connection.

  For this reason, no voltage difference is generated in the optical fiber core wire 6 at the portion of the hole 11, and the fiber core wire 6 does not break due to partial discharge or dielectric breakdown.

  On the other hand, on the ground potential portion side, the optical fiber core wire 6 is provided with a slack 6a and then fixed to the potential fixing member 22 to secure a certain amount of slack A, thereby fixing the potential at the same potential as the ground potential. It is drawn downward through the member 22.

  At this time, from the above calculation, the potential of the optical fiber core wire 6 at the position of the hole 21 of the metal container 5 is 17 kV, the potential of the core wire positioning member 9 provided with the hole 21 is 0 kV (ground potential), and a difference voltage of 17 kV is obtained. appear.

  When the optical fiber core wire 6 is simply passed through the hole 21, the optical fiber core wire 6 approaches the hole 21, but a state such as a minute gap that does not contact the edge of the hole 21 continues. The optical fiber core wire 6 may be damaged or broken due to insulation breakdown.

  Therefore, in this example, by providing the core wire insertion hole 21 on the upper part of the metal container 5 in the core wire positioning member 9 using an insulating material, a sufficient insulation distance can be secured, and partial discharge or insulation breakdown occurs. The optical fiber core wire 6 is not broken. In particular, when the core wire positioning member 9 is a plate-shaped member mainly composed of a fluororesin or the like, the sliding property, the insulating property, and the durability are excellent, and the insulating property and the durability can be secured.

  The voltage is also applied to the optical fiber core wire 6 in the creeping direction. Usually, the optical fiber core wire 6 is made of a glass material at a portion through which light as a signal passes, but its outer surface is usually made of acrylic or the like for the purpose of securing its strength and preventing scratches on the glass material surface. Protective material is coated. Since these protective materials are insulators, they have at least about 10 kV / cm in dielectric strength in the creepage direction. Therefore, from this value, the withstand pressure in the creeping direction of the optical fiber core wire 6 in the insulator tube 4 and the metal containers 2 and 5 can be sufficiently ensured.

  Furthermore, since the insulator type optical current transformer is assumed to be installed outdoors, the temperature of the adhesive fixing portion of the optical fiber core wire 6 is considered in consideration of the influence of heat generated by energization and the influence of solar radiation on the outside air temperature. Will be exposed to an environment of -30C to 70C.

  In such an installation environment, stress may be applied to the optical fiber core wire 6 due to thermal expansion or thermal contraction of the potential fixing member 22 and the adhesive, causing a loss of light amount or the like, which may degrade the state of light. In the present embodiment, the silicone adhesive 13 having a low hardness after curing is used as the adhesive.

  As a result, even if thermal expansion or thermal contraction occurs, no stress is applied to the optical fiber core wire 6 and the light state such as loss of light quantity does not deteriorate.

  As described above, according to this embodiment, the metal container 2 of the high voltage portion and the metal container 5 of the ground potential portion are vertically arranged, and the containers 2 and 5 are connected to each other by the hollow insulator tube 4. In the configured insulator type optical current transformer, the optical fiber core wire 6 connected to the photocurrent sensor 3 accommodated in the metal container 2 is inserted into the hole 11 of the metal container 2 and the hole 21 of the metal container 5 to insert the insulator tube. By arranging the photocurrent transformer in a substantially linear manner at a substantially central portion in the inside 4, it is possible to provide an insulator-type optical current transformer with good assemblability, low cost, and high reliability.

  Although an embodiment of the present invention has been described, this embodiment is provided by way of example and is not intended to limit the scope of the invention. The new embodiment can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and their equivalents.

  In the above embodiment, the core wire positioning member 9 including the upper hole 21 of the metal container 5 is made of an insulating material such as fluororesin. However, the lower hole 11 of the metal container 2 is made of a ring member made of fluororesin. Alternatively, both or one of the holes 11 and 21 may be made of an insulating material.

  DESCRIPTION OF SYMBOLS 1 ... Conductor, 2 ... Metal container (high voltage part side), 3 ... Photocurrent sensor, 4 ... Insulator tube, 5 ... Metal container (ground potential part side), 6 ... Optical fiber core wire, 7 ... Opening, 8 ... Lid, 9 core positioning member, 10 holding member, 11 hole (bottom part of metal container 2), 12 potential fixing member (high voltage part), 13 silicone adhesive, 21 hole (of metal container 5) Upper surface part), 22... Potential fixing member (ground voltage part side).

Claims (8)

A metal conductor through which a current flows and a photocurrent sensor that measures a current flowing through the metal conductor and converts the current into an optical signal are housed, and an optical fiber line for transmitting an optical signal drawn from the photocurrent sensor is inserted into a lower portion of the container. A first metal container provided with a first hole for
A second metal container provided at a grounded portion, wherein a second hole for inserting the optical fiber wire in the upper portion of the container is provided to face the first hole;
A hollow porcelain tube in which the first metal container is disposed above and the second metal container is disposed below, and which is disposed so as to connect between the metal containers;
It is pulled out from the photocurrent sensor, is inserted through the first hole in the first metal container and the second hole in the second metal container, and hangs linearly at a substantially central portion in the insulator tube. an optical fiber lines arranged to,
A potential fixing member supported in the second metal container and fixing the optical fiber line with an extra length portion;
With
The extra length portion,
A = √ (L ² + δ ² ) -L (Equation 1)
δ = F · L ³ / (3 · E · I)
Where L is the length of the insulator tube
F: Concentrated load acting on the insulator head
E: Young's modulus of insulator tube
I: Second moment of area of insulator tube
δ: Displacement of insulator head
A: Amount of sag
An insulator type optical current transformer having a sag amount A calculated by the above (Equation 1) or more .   The insulator type optical current transformer according to claim 1, wherein a plurality of the first holes and the second holes are arranged near an axis of the insulator tube so as to pass a plurality of optical fiber lines. The insulator-type optical current transformer according to claim 1 or 2, wherein the surface roughness of the inner peripheral surface of each of the first hole and the second hole is smaller than 25S. One of claims 1 to 3, characterized in that said at least one portion of the bore of the second hole of the first hole and the second metal containers of the first metal container and an insulating material 2. The insulator type optical current transformer according to claim 1. The insulator type current transformer according to claim 4 , wherein a fluororesin is used as a main material of the insulating material. The potential fixing member according to any one of claims 1 to 5 , further comprising a potential fixing member disposed near the first hole so as to have a potential equivalent to that of the first metal container, and fixed to the optical fiber line. Insulator type optical current transformer. It said potential fixing member, wherein are arranged such that the same potential and the second metal containers in the vicinity of the second hole, according to any one of claims 1 to 6 were fixed to the optical fiber line Insulator type optical current transformer. Insulator type optical current transformer according to claim 6 or claim 7 using a silicone adhesive to fixation of the optical fiber line.

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