Optical type current measuring instrument

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a current measuring device for measuring a conductor energizing current such as a gas-insulated bus, and particularly to an optical current measuring device.

【0002】

[Conventional technology]

Figure 10 shows the configuration of the optical current measuring device using the conventional technology. A GIS or gas insulating bus is composed of a tank 1 filled with an insulating gas and a conductor 2 supported by an insulating spacer 3. In order to detect the current flowing through the conductor 2, a Faraday element 4 such as lead glass or an optical fiber having a Faraday effect is orbited so as to surround the energizing current of the conductor 2 to form an optical path. In FIG. 11, the optical fiber 4 having a Faraday effect is fixed to the tank 1 by the holding material 5 and the insulating material 6, and the photoelectric conversion unit 9 and the calculation output unit 10 are arranged outside the tank of the airtight terminal 8 penetrating the tank 1. ing. The end of the optical fiber 4 is connected to the polarizer 12 and the analyzer 13 to transfer light. The optical fiber 4 wound a plurality of times is put together and supported by the holding material 5 with a presser 7.

【0003】

Next, the operation will be described with reference to the optical path diagram shown in FIG. The light emitted from the light emitting diode 14 of the photoelectric conversion unit 9 passes through the airtight terminal 8 in the optical fiber 11 for sending and receiving light, enters the polarizer 12 arranged inside the tank 1, and is linearly polarized. This light enters the optical fiber 4, and the light whose polarization plane is rotated by the magnetic field created by the energizing current of the conductor 2 is incident on the analyzer 13. The light split into vector light of two right-angled components (X and Y components) by the detector 13 becomes a light amount signal and returns to the photoelectric conversion unit 9 again, is converted into an electric signal by the photodiode 15, and then the arithmetic output unit. The current value is obtained by performing the calculation according to 10.

【0004】

[Problems to be Solved by the Invention]

However, in the conventional optical current measuring device, since the Faraday element is brought close to the conductor 2 and the insulation is supported by the insulating material 6 from the tank 1, the structure is complicated when applied to the polyphase gas insulating bus. There is a drawback. In addition, there is a risk that the Faraday element will cause an error due to the influence of heat generated by the conductor 2.

【0005】

On the other hand, when the optical fiber 4 is used as the Faraday element, birefringence is likely to occur due to heat or mechanical stress. There is a problem that this birefringence causes polarization disturbance and causes a measurement error. In the conventional example of FIG. 11, since the lead glass of the Faraday element is replaced with the optical fiber 4, the optical fiber 4 is partially stressed by the holding 7 to increase the birefringence. In addition, with this holding method, it is unavoidable to generate stress due to transmitted vibration / impact. Since the optical fiber 4 is so sensitive that it generates stress when bent into a coil (inversely proportional to the diameter), the structure shown in FIG. 11 is stressed even when it is handled during assembly. In addition, due to temperature changes, stress is applied due to thermal expansion and contraction. Therefore, these stresses increase birefringence and reduce the accuracy of the measurement. The present invention has been proposed to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an optical current measuring device having improved measurement accuracy.

【0006】

[Means for solving problems]

The present invention is an optical current measuring device for measuring the energizing current of the energizing conductor of a gas insulating device in which an energizing conductor is arranged in a tubular tank filled with an insulating gas. An insulating plate-shaped member having an opening through which a conductor is inserted and having an outer periphery fixed to the inner wall of the tubular tank is arranged, and an optical fiber that circulates the current-carrying conductor is placed on the plate-shaped member as a cushioning material from above. An annular member to be fixed is attached to both ends of the optical fiber, and predetermined optical devices are attached to both ends of the optical fiber, and the current is measured based on the polarization state of the light passing through the optical fiber due to the Faraday effect.

【0007】

[Action]

By arranging and fixing an annular member that protects and stores the optical fiber on a plate-shaped member whose outer circumference is fixed to the inner wall surface of the tank, it is possible to avoid stress and heat effects on the optical fiber, suppress birefringence, and cause measurement error. Can be resolved.

【0008】

[Example]

Examples of the present invention will be described in detail below. FIG. 1 shows an example in which an optical current measuring device is configured in a single-phase GIS using an optical fiber 4 as a Faraday element. The holding material 5 to which the optical fiber 4 is attached is an insulating disk inscribed in the tank 1, and uses glass epoxy or a resin used for a spacer. In this embodiment, it is inserted into the step portion of the tank 1 and fixed with the fixing material 17. The holding material 5 is provided with an opening that also serves as a flow port for insulating gas at a position where the conductor 2 penetrates. This caliber should be as large as possible to ensure insulation from the conductor 2 of the high-voltage power supply and to facilitate insertion of the conductor 2 during assembly, and is preferably twice the caliber of the conductor 2. Select above. Next, the ring 16 containing the optical fiber 4 is arranged concentrically in the opening of the holding material 5 and fixed by the presser 7. At this time, the optical fiber 4 is arranged on the ring 16 via the cushioning material 19. A single-mode optical fiber having a Faraday effect is used for the optical fiber 4, and a bundle-shaped coil having a number of turns suitable for the detection sensitivity is adopted.

【0009】

The optical path configuration of Fig. 1 is shown in Fig. 2. This is the same as the optical path diagram described in the conventional configuration of FIG. Next, the actions and effects brought about by this example will be described. By arranging the ring 16 containing the optical fiber 4 away from the conductor 2, the winding diameter of the optical fiber 4 is set to the maximum allowable value (arrangement with the polarizer 12 etc. in single phase, in three phase). Since it can be done (until the rings 16 of each phase come into contact with each other), the curvature of the optical fiber is softened to reduce the bending stress. There is also a method of erasing the birefringence caused by bending stress by twisting the optical fiber, but it is effective to select a structure that reduces the stress from the beginning. Further, since it can be separated from the conductor 2 which is a heat generating source when energized, the temperature difference affecting the optical fiber 4 is reduced and the generation of stress is suppressed. When the optical fiber 4 is housed in the ring 16, the wrapping shape of the optical fiber 4 is adjusted by using, for example, cotton-like glass fiber for a heat insulating material as the cushioning material 19. This buffer structure has an action of shielding the optical fiber 4 from the heat transferred to the ring 16 and an action of keeping the optical fiber 4 soft so as not to apply stress. Since it also has the effect of blocking the stress on the optical fiber 4 due to vibration, shock, etc., it suppresses birefringence in addition to the above action and solves the problem of measurement error. In terms of handling the optical fiber 4, the ring 16 made of a mechanically durable material (stainless steel or the like) acts as a protective ring for the stress-sensitive optical fiber 4, which facilitates assembly work and the like.

【0010】

As a result, it is possible to solve the problem that birefringence increases due to stress and the accuracy decreases. Figure 3 shows an example of application to three-phase GIS. This is an example in which the polarizer 12 and the analyzer 13 are arranged on the holding material 5, but there is also a method of increasing the diameter of the ring 16 by installing it on the wall surface of the tank 1 as shown in FIG. In addition, there are many configurations such as a configuration in which the ring 16 is made of non-metal, a configuration in which a shield is added around the ring 16 to alleviate an electric field, a configuration in which the holding material 5 is made of metal, a configuration in which the holding material 5 is provided with a degassing window, and the like. Variations are possible.

【0011】

FIG. 4 shows an example in which an optical current measuring device is configured in a single-phase GIS using an optical fiber 4 as a Faraday element. The holding material 5 to which the optical fiber 4 is attached is an insulating disk inscribed in the tank 1, and uses glass epoxy or a resin used for a spacer. In this embodiment, it is inserted into the step portion of the tank 1 and fixed with the fixing material 17. The holding material 5 is provided with an opening that also serves as a distribution port for insulating glass at a position where the conductor 2 penetrates. This diameter should be as large as possible to ensure insulation from the conductor 2 of the high-voltage power supply section and to facilitate insertion of the conductor 2 during assembly, and is preferably twice the diameter of the conductor 2. Select above. Next, the optical fiber 4 is housed inside the groove 21 provided on the side surface of the holding material 5, arranged concentrically in the conductor 2 through hole of the holding material 5, and sealed with the presser 7. Fig. 5 is an enlarged view of part A in Fig. 4. The optical fiber 4 is arranged in the groove 21 via the cushioning material 19. A single-mode optical fiber having a Faraday effect is used for the optical fiber 4, and a bundle-shaped coil having a number of turns suitable for the detection sensitivity is adopted.

【0012】

The optical path configuration in Fig. 4 is the same as in Fig. 2. Next, the actions and effects brought about by this example will be described. By arranging the groove 21 containing the optical fiber 4 away from the conductor 2, the winding diameter of the optical fiber 4 can be set to the maximum allowable value, so that the curvature of the optical fiber is softened and the bending stress is lowered. Further, since it can be separated from the conductor 2 which is a heat generating source when energized, the temperature difference affecting the optical fiber 4 is reduced and the generation of stress is suppressed. When the optical fiber 4 is housed in the groove portion 21, the wrapping shape of the optical fiber 4 is adjusted by using, for example, a cotton-like graphs fiber for a heat insulating material in the cushioning material 19. This buffer structure has an action of shielding the optical fiber 4 from the heat reaching the groove 21 and an action of keeping the optical fiber 4 soft so as not to apply stress. Since it also has the effect of blocking the stress on the optical fiber 4 due to vibration, shock, etc., it suppresses birefringence in addition to the above action and solves the problem of measurement error. Further, since the fiber 4 is mounted in the groove 21 in advance and then the holding material 5 is incorporated in the tank 1, the assembly work can be performed without directly touching the stress-sensitive fiber 4.

【0013】

As a result, it is possible to solve the problem that birefringence increases due to stress and the accuracy decreases. Figure 6 shows an example of application to three-phase GIS. This is an example in which the polarizer 12 and the analyzer 13 are arranged on the holding material 5. Further, there is also a configuration in which the groove portion 21 is installed on the side surface of the holding material 5 as shown in FIG. 5 and is installed on the inner diameter side (closer to the conductor 2) of the holding material 5 as shown in FIG. In addition, many variations are conceivable, such as a structure in which the cross-sectional shape of the groove 21 is rectangular or semi-circular.

【0014】

FIG. 8 shows an example in which an optical current measuring device for GIS is configured by using an optical fiber 4 as a Faraday element. In the method of attaching the optical fiber 4 to the tank 1, the optical fiber 4 is housed inside the protective ring 16 whose outer diameter is inscribed in the tank 1, and the optical fiber 4 is arranged and fixed to the inner wall of the tank 1 by the holding material 5. At this time, as shown in FIG. 9, the optical fiber 4 is arranged on the protective ring 16 via the cushioning material 19. A single-mode optical fiber having a Faraday effect is used for the optical fiber 4, and a bundle-shaped coil having a number of turns suitable for the detection sensitivity is adopted.

【0015】

The optical path configuration of FIG. 9 is the same as that of the optical path diagram of FIG. Next, the action and effect of the buffer structure according to this example will be described. When the optical fiber 4 is housed in the protective ring 16, as shown in FIG. 9, the cushioning material 19 is provided with, for example, cotton-like glass fiber for a heat insulating material, and the wrapped shape of the optical fiber 4 is adjusted. However, the optical fiber 4 has a problem that stress is generated when the strands of the wound bundle touch or rub against each other, and the effect is low unless the cushioning material 19 is inserted between the strands. Therefore, as shown in the enlarged view shown in FIG. 10, a thin tubular cushioning material 19'is used. Before processing the optical fiber 4 into a bundle, after inserting the optical fiber 4 into the cushioning material processed into a tube shape with an outer diameter of about 2-3 mm, it is necessary for the sensitivity of the sensor according to the diameter of the protection ring 16. Roll the number of times to make a bundle. The thin tubular cushioning material 19'is an ultra-fine, cotton-like cushioning material using glass fiber or the like, and the diameter of the cushioning material 19'is formed in the cushioning material. It is difficult in manufacturing to provide a hole for inserting a single-mode optical fiber of about 0.3 mm. Therefore, the thin tubular cushioning material 19'is made into a concentric double structure, a solid layer optical fiber insertion tube 20 is provided, and a soft cushioning layer is formed on the solid layer optical fiber insertion tube 20. The optical fiber insertion tube 20 uses a resin-based material with an inner diameter of 1 mm or less, and by obtaining a smooth inner surface that makes it easy to insert the optical fiber 4, a guide that prevents the end of the optical fiber from protruding from the center of the hole to the outside of the tube. Give it the role of a tube.

【0016】

For the optical fiber insertion tube 20 and the binder or the like used to form the thin tubular cushioning material 19'on the outside of the tube, select a material that can be easily removed by heat firing or chemical treatment. As a result, only the layered tubular portion of the fluffy thin tubular cushioning material 19'remains around the wire of the optical fiber 4, and all the optical fibers 4 in the protective ring 16 can be housed in a soft cushioning structure. it can.

【0017】

Since the optical fiber 4 forms a cushioning structure with the hard protective ring 16 by the cushioning material 19, the optical fiber 4 is shielded from the heat reaching the protective ring 16 and is held flexibly to avoid the influence of stress. Can be done. Since it also has the effect of blocking the stress on the optical fiber 4 due to vibration, shock, etc., it suppresses birefringence in addition to the above action and solves the problem of measurement error. In terms of handling the optical fiber 4, the protective ring 16 made of a mechanically durable material (stainless steel or the like) acts as a protective ring for the stress-sensitive optical fiber 4, which facilitates assembly work and the like.

【0018】

As a result, it is possible to solve the problem that birefringence increases due to stress and the accuracy decreases. This buffer structure can also be applied to the above-described embodiment. If the protective ring 16 is arranged on the disk-shaped holding material 5, it can be used for single phase, and if the number of conductors 2 is three, it can be used for three phase. As described above, it is clear that it can be applied to other optical measuring devices that handle single-mode optical fibers having a Faraday effect.

【0019】

[Effect of the invention]

With the above configuration, it is possible to provide a measuring device capable of performing optical current measurement with improved accuracy.

[Simple explanation of drawings]

[Figure 1]

Schematic diagram of a configuration of an optical current measuring device according to an embodiment of the present invention [Figure 2]

Optical path configuration diagram between optical elements in FIG. [Fig. 3]

Illustrated configuration example according to another embodiment of the present invention [Fig. 4]

Illustrated configuration example according to another embodiment of the present invention [Fig. 5]

Detailed view of part A in Fig. 4 [Fig. 6]

Illustrated configuration example according to another embodiment of the present invention [Fig. 7]

Detailed view of a main part according to another embodiment of the present invention [Fig. 8]

Illustrated configuration example according to another embodiment of the present invention [Fig. 9]

Detailed view of the main part of Fig. 8 [Fig. 10]

Detailed view of the main part of Fig. 9 [Fig. 11]

Configuration example diagram of a conventional optical current measuring device [Fig. 12]

Optical path configuration diagram of the optical element of FIG. [Explanation of symbols]

1 ... tank 2 ... conductor 3 ... Insulation spacer 4 ... Optical fiber 5 ... Retaining material 6 ... Insulation 7 ... hold down 8 ... Airtight terminal 9 ... Photoelectric converter 10 ... Calculation output section 11 ... Optical fiber 12 ... Polarizer 13 ... Photon 14 ... light emitting diode 15 ... photodiode 16 ... ring 17 ... Fixing material 18 ... Polarizer / detector unit 19 ... Cushioning material 19'... Thin tubular cushioning material 20 ... Fiber optic intubation 21 ... Groove 30 ... Condensing lens 31 ... Optical connector