JPH0572123A - Monitoring device for gas in insulating oil of oil filled cable - Google Patents

Abstract

PURPOSE:To enable constant monitoring of gas in oil which is generated in the insulating oil of an OF cable without suspending the current-carrying to the OF cable. CONSTITUTION:The gas monitoring device is equipped with a separating and catching means 9 for the gas in oil which is installed on a connection box, etc., for the connection of the OF cable and separates and catches the gas in oil consisting of plural components contained in insulating oil from the insulating oil and an optical transmission passage 14 which is installed on the gas separating and catching means and is formed, passing through the environment in which the caught gas in oil of plural components is mixed. Further, the gas monitoring device is equipped with a luminous means 16 which generates the light which has a variety of wave length equal to each absorption spectrum of a plurality of components contained in the gas in oil and superposes the light components having different wave length, light receiving means 22 which separately extracts the light component having a single wave length equal to the above-described absorption spectrum from the light which is formed by the superposition of a variety of wave length and carries out photoelectric conversion, and a transmission means 26 which conducts light by joining the luminous means, light receiving means, and the light transmission passage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel OF cable insulating gas in insulating oil monitoring apparatus, and more particularly to a gas in oil generated in the insulating oil of the OF cable for energizing the OF cable. OF case that enables constant monitoring without stopping
It relates to a device for monitoring gas in insulating oil of Bull.

[0002]

2. Description of the Related Art Generally, an OF cable is used as a cable for transmitting electric power. The OF cable is a cable in which a conductor for transmitting electric power is covered with insulating oil having a high insulating property. When the OF cable deteriorates, heat is generated and the insulating oil is heated, or partial discharge occurs inside. It is known that the insulating oil is decomposed by such heating and discharge to generate hydrogen, hydrocarbon gas (methane, acetylene, etc.), carbon monoxide, carbon dioxide and the like. Therefore, if these gases contained in the insulating oil are monitored, the OF case
It is possible to detect insulation deterioration of the bull. Conventionally, the following work has been performed to monitor such a gas in insulating oil.

[0003] First, for safety, after the energization of the OF cable is stopped, the insulating oil is collected from the oil supply port provided in the connection box of the OF cable. The gas dissolved in the insulating oil is separated by reducing the pressure of the collected insulating oil. The gas components of the separated gas are measured by chromatography or the like. In this way, the insulation deterioration of the OF cable can be detected by measuring the gas component.

On the other hand, although it is not an OF cable, in a transformer incorporating insulating oil, in addition to performing the same work as described above, it is also possible to provide the transformer with a detector for constant monitoring. There is. That is, a gas-in-oil separator using a polymer membrane is provided, and a sensor for electrically detecting gas is provided, and the oil-in-oil gas in the insulating oil is separated by the gas-in-oil separator and detected by the sensor. Attempts are being made.

[0005]

The monitoring of the OF cable as described above has the following problems.

(1) In order to collect the insulating oil, it is necessary to stop the energization of the OF cable, and the measurement cannot be performed at any time. That is, since it is not possible to constantly monitor, it is not possible to detect an abnormality early.

(2) There is a large amount of work such as collecting insulating oil on the spot, taking it home, gas analysis and measurement.

In addition, there are the following problems in applying the constant monitoring device attempted in the transformer to the OF cable.

(1) Only one kind of gas is detected,
In addition, the measurement accuracy is low.

(2) Since the sensor is an electric type, it cannot be applied to a power cable which is exposed to a strong electromagnetic field over a long distance and is installed in a humid environment.

In order to solve the above problems, the applicant of the present invention paid attention to the optical properties of gas, and considered the use of this to provide a device for detecting gas in the OF cable.
That is, when light passes through gas, light of a specific wavelength is absorbed according to the concentration of the gas. Therefore, the gas concentration can be measured by measuring the amount of absorption.

Therefore, an object of the present invention is to solve the above-mentioned problems by using an optical device, and to prevent the gas in the oil generated in the insulating oil of the OF cable from stopping the energization of the OF cable.
An object of the present invention is to provide an OF-cable in-oil gas monitoring device that enables constant monitoring.

[0013]

In order to achieve the above object, the first invention is to insulate gas in oil composed of a plurality of components contained in insulating oil, which is attached to a connection box or the like for connecting OF cables. Optical transmission formed by passing through an atmosphere in which an in-oil gas separation / capturing means for separating and capturing from oil and an in-oil gas consisting of a plurality of components trapped in the in-oil gas separation / trapping means are mixed Path, a light emitting means for generating light having different wavelengths that match the absorption spectra of each of the plurality of components contained in the gas in oil, and superimposing the light having these different wavelengths, and the light having the different wavelengths superimposed And a light receiving means for separating and extracting a light component of a single wavelength that matches the absorption spectrum and performing photoelectric conversion, and a transmitting means for connecting the light emitting means and the light receiving means to the light transmission path to guide light. It is configured.

A second aspect of the present invention is an oil-in-gas separation / capture means which is attached to a connection box or the like for connecting OF cables to separate and capture in-oil gas contained in insulating oil, and the in-oil gas. A pair of optical fibers optically inserted at a predetermined interval in the gas-in-oil separation / capture means provided through the minute-capture means from the outside, and a plurality of in-oil gas separated from the insulating oil A plurality of laser devices for generating a plurality of laser lights having wavelengths equal to the respective infrared absorption spectra, and reference signals set to predetermined values respectively corresponding to the plurality of laser lights. With a different carrier frequency to generate a modulation signal, and a plurality of laser drive circuits for respectively driving the laser device by the modulation signals, and a plurality of lasers provided at one end of the optical fiber. Note that the light is superimposed An optical coupler, a photodetector provided at the other end of the optical fiber for converting the plurality of laser lights into electric signals, and the electric signals are detected and demodulated at the different carrier frequencies to obtain demodulated signals. A plurality of detection circuits that generate and detect the attenuation amount of the laser light from the demodulated signal are provided.

A third aspect of the present invention is an oil-in-gas separation / capturing means which is attached to a connection box or the like for connecting an OF cable to separate and capture in-oil gas contained in insulating oil. A pair of optical fibers optically inserted at a predetermined interval in the gas-in-oil separation / capture means provided through the separation-capture means from the outside, and a plurality of in-oil gases separated from the insulating oil A plurality of laser devices that generate a plurality of laser lights having wavelengths equal to the respective infrared absorption spectra, and a laser drive circuit that drives the laser devices based on a predetermined value, An optical coupler provided at one end of the optical fiber to superimpose and inject the plurality of laser lights, and a spectroscopic device provided at the other end of the optical fiber to disperse the plurality of laser lights into respective wavelengths. And the plurality of laser beams split into A plurality of light detecting devices for converting into electrical signals Re, each of les than the electrical signal - is constituted by a plurality of detection circuits for detecting the laser light attenuation.

Further, a fourth aspect of the present invention is a device for monitoring a gas in insulating oil of an OF cable according to the third aspect, wherein a plurality of laser devices are provided side by side and separated from the insulating oil. A laser device that generates a reference laser beam having a wavelength that does not absorb gas in oil, and a photodetector that converts the reference laser beam dispersed by the spectroscopic device into an electric signal, And a comparator circuit for comparing the electric signals converted from the plurality of laser beams with the electric signals converted from the reference laser beam to detect the attenuation of each laser beam. ing.

[0017]

With the above construction, in the first invention, the OF
The in-oil gas separation / capture means attached to a connection box or the like for connecting the cables separates and captures the in-oil gas consisting of a plurality of components contained in the insulating oil from the insulating oil. The optical transmission path provided in the oil-in-oil separation and capturing means is formed by passing through an atmosphere in which the in-oil gas composed of a plurality of captured components is mixed. On the other hand, the light emitting means generates light having different wavelengths that match the absorption spectra of each of the plurality of components contained in the oil-in-gas, and superimposes light having these different wavelengths. The light on which the different wavelengths are superimposed is guided to the optical transmission line by the transmission means. Since the optical transmission line is formed by penetrating through an atmosphere in which the in-oil gas consisting of a plurality of components trapped in the oil-in-gas separating and capturing means is mixed, the in-oil gas has an absorption spectrum of each component. Absorb matching light. Therefore, in the downstream of the optical transmission line, the amount of transmitted light is reduced according to the concentration of each component contained in the oil-in-gas. The transmitted light is guided to the light receiving means by the transmitting means. The light guided to the light receiving means is separately extracted and photoelectrically converted into a light component having a single wavelength that matches the absorption spectrum. The magnitude of this photoelectrically converted signal is obtained according to the concentration of each component contained in the gas in oil. That is, it is possible to specify the type of gas contained in the insulating oil and detect the concentration thereof.

According to the second aspect of the invention, the in-oil gas composed of a plurality of components contained in the insulating oil is separated by the in-oil gas separating and capturing means attached to the connection box or the like for connecting the OF cable. It is separated from the insulating oil and captured. A pair of optical fibers, which are inserted from the outside into the oil-in-oil content capturing means and are provided at a predetermined interval, pass through an atmosphere in which the in-oil gas consisting of a plurality of captured components is mixed and optically. Will be combined. On the other hand, the plurality of laser devices generate a plurality of laser lights having a wavelength equal to the infrared absorption spectrum of each of the plurality of oil-in-gas separated from the insulating oil. At this time, the plurality of laser drive circuits modulate the reference signals set to predetermined values corresponding to the plurality of laser lights with different carrier frequencies to generate modulated signals. Each of the laser devices is driven by this modulated signal. The plurality of laser lights thus modulated are superimposed by the optical coupler provided at one end of the optical fiber and injected into the optical fiber. The laser light injected into the above-mentioned optical fiber is transmitted through the atmosphere in which the in-oil gas consisting of a plurality of captured components is mixed and is injected into the other optical fiber. During this time, the gas in oil absorbs light that matches the absorption spectrum of each component. A photodetector provided at the other end of this optical fiber converts the laser light into an electric signal. Since this electric signal is modulated, it is detected and demodulated by the plurality of detection circuits at the different carrier frequencies to generate a demodulated signal. From this demodulated signal
The light attenuation can be detected. It is possible to specify the type of gas contained in the insulating oil and detect its concentration.

Further, in the third aspect of the invention, the oil-in-gas consisting of a plurality of components contained in the insulating oil is removed by the oil-in-gas separating / capturing means attached to the connection box or the like for connecting the OF cable. It is separated from the insulating oil and captured. A pair of optical fibers, which are inserted from the outside into the oil-in-oil content capturing means and are provided at a predetermined interval, pass through an atmosphere in which the in-oil gas consisting of a plurality of captured components is mixed and optically. Will be combined. On the other hand, the plurality of laser devices generate a plurality of laser lights having a wavelength equal to the infrared absorption spectrum of each of the plurality of oil-in-gas separated from the insulating oil. At this time, the laser drive circuit drives the laser device based on a predetermined value. The plurality of laser lights driven in this way are superposed by an optical coupler provided at one end of the optical fiber and injected into the optical fiber. The laser light injected into the above-mentioned optical fiber is transmitted through the atmosphere in which the in-oil gas consisting of a plurality of captured components is mixed and is injected into the other optical fiber. During this time, the gas in oil absorbs light that matches the absorption spectrum of each component. A spectroscopic device provided at the other end of the optical fiber disperses the plurality of laser lights into respective wavelengths. The plurality of photo detectors respectively convert the plurality of dispersed laser lights into electric signals. The detection circuit can detect the attenuation amount of each laser light from the electric signal. It is possible to specify the type of gas contained in the insulating oil and detect its concentration.

According to the fourth aspect of the invention, the in-oil gas composed of a plurality of components contained in the insulating oil is separated by the in-oil gas separating and capturing means attached to the connection box or the like for connecting the OF cable. It is separated from the insulating oil and captured. A pair of optical fibers, which are inserted from the outside into the oil-in-oil content capturing means and are provided at a predetermined interval, pass through an atmosphere in which the in-oil gas consisting of a plurality of captured components is mixed and optically. Will be combined. On the other hand, a plurality of laser devices have a plurality of laser lights having a wavelength equal to the infrared absorption spectrum of each gas in oil separated from the insulating oil, and a plurality of laser lights separated from the insulating oil. And a reference laser light having a wavelength that does not absorb the gas in the oil. At this time, the laser drive circuit drives the laser device based on a predetermined value. The plurality of laser lights driven in this way are superposed by an optical coupler provided at one end of the optical fiber and injected into the optical fiber. The laser light injected into the above-mentioned optical fiber is transmitted through the atmosphere in which the in-oil gas consisting of a plurality of captured components is mixed and is injected into the other optical fiber. During this time, the gas in oil absorbs light that matches the absorption spectrum of each component. A spectroscopic device provided at the other end of the optical fiber disperses the plurality of laser lights and the reference laser light into respective wavelengths. The plurality of photo detectors respectively convert the plurality of dispersed laser light and the reference laser light into electric signals. The detection circuit detects the attenuation amount of each laser light from the electric signal. The comparison circuit compares the electric signal converted from the plurality of laser lights with the electric signal converted from the reference laser light to obtain a laser.
The light attenuation is corrected. This makes it possible to identify the type of gas contained in the insulating oil and detect its concentration. Further, the influence of the transmission loss on the measurement can be corrected from the attenuation amount of the reference laser light.

[0021]

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the present embodiment, acetylene and methane of the insulating oil gas were monitored. It is said that acetylene is mainly generated when a partial discharge occurs in insulating oil, and methane is mainly generated when the insulating oil is heated. Therefore, by monitoring these two types of gas in oil, The deterioration of the bull can be detected.

Hydrocarbon gas such as acetylene and methane has a property of absorbing light of a specific wavelength due to rotation and vibration of molecules, and such a specific wavelength is called an absorption spectrum. The absorption spectrum is unique to the gas, and one type of gas discretely has absorption spectra of a plurality of wavelengths. Further, it is known that the absorption amount depends on the gas concentration. Therefore, at the wavelength corresponding to the absorption spectrum, if the intensity of the light irradiated into the gas and the distance of transmission are known, the concentration of the gas can be measured by measuring the intensity of the light after the transmission. Further, even if two or more kinds of gases are mixed, since the absorption spectra of the gases are different from each other, they do not optically affect each other, so that they can be measured independently.

Further, as the light which efficiently generates such a specific wavelength and has little attenuation in the transmission line,
Since the laser light is effective, in this embodiment, the infrared laser light is used and the optical fiber is used as the transmission path of the infrared laser light.

As shown in FIG. 1, a power line 2 formed by using an OF cable 1 made by coating a conductor with insulating oil has a long distance, although not shown in the figure,
A large number of F cables 1 are connected to each other. The connection box 3 provided at the end of the OF cable 1 for connecting the OF cables 1 to each other is butted against and joined to the connection box 3 of the adjacent OF cable 1 for electrical connection. In addition to achieving the above, an insulating oil seal is applied. A sealed container 4 is provided in the outer shell of the connection box 3, and the connection box 3 and the sealed container 4 are connected by a joint 5. Container 4
Is divided into two sections by a filter 6 provided so as to partition the inside thereof. Of the two compartments, the compartment provided with the joint 5 and communicating with the connection box 3 forms a liquid phase chamber 7 for introducing the insulating oil L. The filter 6 is formed by fusing a polymer film on a porous metal.
It has the property of passing oil but not gas. That is, when the insulating oil L filled in the liquid phase chamber 7 contains a gas, only this gas can pass through the filter 6. The other section partitioned by the filter 6 forms a gas phase chamber 8 for trapping the gas G passing through the filter 6. As described above, the container 4 provided with the filter 6 that selectively passes only the gas is
This means that the in-oil gas separation / capturing means 9 for separating and capturing the gas G contained in the insulating oil L is constituted.
Gas G separated by the filter 6 and trapped in the gas phase chamber 8
Include hydrogen generated by decomposing the insulating oil L, hydrocarbon gas (methane, acetylene, etc.), carbon monoxide, carbon dioxide, and the like.

Of the gas-in-oil separation / capture means 9, the gas phase chamber 8 which is responsible for gas capture is provided with optical fibers 10 and 11 constituting a transmission means 26, which will be described later, inserted therein. Each of the ends 12 and 13 has a vapor phase chamber 8
They are arranged facing each other at a predetermined interval.
The ends 12 and 13 of the optical fibers 10 and 11 form an optical transmission line 14 that transmits through an atmosphere in which an in-oil gas composed of a plurality of components trapped in the gas phase chamber 8 is mixed.

A monitoring box 15 provided at a monitoring station or the like, apart from the connection box 3 to which the means for capturing and separating gas in oil 9 is attached, absorbs each of a plurality of components contained in the gas G in oil. Light emitting means 1 for generating light having different wavelengths matching a spectrum and superimposing light having these different wavelengths
6 is provided. Specifically, the light emitting means 16 includes a laser device 17 for generating laser light having a wavelength equal to the infrared absorption spectrum of acetylene, and a laser light having a wavelength equal to the infrared absorption spectrum of methane. A laser device 18 for generating and a reference signal S1 set to a predetermined value are modulated at a predetermined carrier frequency C1 to generate a modulation signal M1 and a laser device 17 is driven by the modulation signal M1. The drive circuit 19 and a reference signal S2 set to a predetermined value are modulated at a carrier frequency C2 different from C1 to obtain a modulation signal M.
2 and the modulation device M2 produces a laser device 18
And a laser drive circuit 20 for driving the laser, and an optical coupler 21 for superimposing the laser lights generated by the laser device 17 and the laser device 18 and injecting them into one optical fiber. There is. The optical coupler 21 is connected to the end of the optical fiber 10 that constitutes the transmission means 26. As described above, the other end 12 of the optical fiber 10 is the gas-in-oil separation / capture means 9,
It is inserted into the gas phase chamber 8 that is in charge of capturing the gas, and forms one end of the optical transmission line 14 that is transmitted through the atmosphere in which the gas G in oil consisting of a plurality of components trapped in the gas phase chamber 8 is mixed. Therefore, the laser lights generated by the laser devices 17 and 18 are superposed by the optical coupler 21 and injected into the optical fiber 10, so that the end 12 of the optical fiber 10 irradiates the optical transmission line 14. Will be configured in.

In this embodiment, the laser device 17 has a wavelength of 1.53 .mu.m and the laser device 18 has a wavelength of 1.66 .mu.m.
It is set to m. This is selected from many absorption spectra of acetylene and methane, and is provided in the infrared region in consideration of transmission through an optical fiber. That is, 1.53 μm is the absorption spectrum of acetylene, and 1.66 μm is the absorption spectrum of methane. Since these have different wavelengths, they do not affect each other.

The monitoring box 15 is provided with a light receiving means 22 for separately extracting and photoelectrically converting a light component of a single wavelength that coincides with the absorption spectrum from light in which different wavelengths are superimposed. The light receiving means 22 is provided by being connected to the end of another optical fiber 11 which constitutes the transmitting means 26.
The photodetector 23 for converting the light into an electric signal M, and the electric signal M output by the photodetector 23 are detected and demodulated at the different carrier frequencies C1, C2 to generate demodulated signals D1, D2 and demodulated. It is composed of a plurality of detection circuits 24 and 25 for detecting the amount of laser light attenuation from the signals D1 and D2. As described above, the other end 13 of the optical fiber 11 is inserted into the gas phase chamber 8 which is in charge of gas trapping in the oil-in-oil separation and capture means 9, and the oil composed of a plurality of components trapped in the gas phase chamber 8 is used. Since one end portion of the optical transmission line 14 that transmits through the atmosphere in which the medium gas is mixed is formed, the laser light emitted from the end portion 12 of the optical fiber 10 to the optical transmission line 14 is the end portion of the optical fiber 11. It is configured such that the light enters the portion 13, is transmitted, and is guided to the light detection device 23. The photodetector 23 has continuous spectral characteristics in the infrared region, and corresponds to the sum of the amount of laser light having a wavelength of 1.53 μm and the amount of laser light having a wavelength of 1.66 μm. Generate an electrical signal M.

The optical fibers 10 and 11 are provided by connecting the oil-in-gas separating / capturing means 9 and the monitoring box 15 which are provided at a distance from each other, and the light emitting means 16 and the light receiving means 22 are provided.
And the optical transmission line 14 are connected to form a transmission means 26 for guiding light. Since the transmission means 26 is composed of the optical fibers 10 and 11, the transmission loss is small even when the distance is large, and the degree of freedom of wiring is large. Also, OF cable 1
Therefore, it is installed without taking a large space and is not affected by a large current flowing through the OF cable 1.

Next, the operation of the embodiment will be described.

When the insulating oil L filled in the liquid phase chamber 7 of the gas-in-oil separation / separation means 9 contains a gas G such as acetylene or methane, these gases pass through the filter 6 and pass through the gas phase chamber. 8 is captured.

In the light emitting means 16, the laser drive circuit 1
Reference numeral 9 modulates a reference signal S1 set to a predetermined value with a predetermined carrier frequency C1 to generate a modulation signal M1. Since the laser device 17 is driven by the modulation signal M1, the laser having a wavelength of 1.53 .mu.m amplitude-modulated in proportion to the modulation signal M1.
The light is obtained. On the other hand, the laser drive circuit 20 modulates the reference signal S2 set to a predetermined value with a predetermined carrier frequency C2 to generate a modulation signal M2. Since the laser device 18 is driven by the modulation signal M2, laser light having a wavelength of 1.66 .mu.m that is amplitude-modulated in proportion to the modulation signal M2 can be obtained. These two laser lights are superposed by the optical coupler 21 and injected into the transmission means 26, that is, the optical fiber 10,
The optical transmission line 14 is irradiated from the end 12 of the optical fiber 10.

Since the optical transmission line 14 is formed in an atmosphere in which the in-oil gas G such as acetylene or methane is mixed, laser light having a wavelength of 1.53 μm and a wavelength of 1.66 μm is transmitted through the optical transmission line 14. As it does so, it will be absorbed and attenuated according to the concentration of acetylene and methane, respectively. In this way, the laser light transmitted through the optical transmission line 14 and attenuated according to the concentrations of acetylene and methane is transmitted to the optical fiber 11.
The light is incident on the end portion 13 of the light source, is transmitted, and is guided to the light detection device 23 that constitutes the light receiving means 22.

In the photo-detecting device 23, an electric signal M proportional to the sum of the amounts of laser light having a wavelength of 1.53 μm and a wavelength of 1.66 μm is obtained by photoelectric conversion. Since the electric signal M is still amplitude-modulated by the carrier frequencies C1 and C2, the detection circuits 24 and 25 detect and demodulate the signals, respectively, to generate demodulated signals D1 and D2. These demodulated signals D
By comparing the values of 1 and D2 with the reference signals S1 and S2, the concentrations of acetylene and methane can be measured. Alternatively,
The values of the demodulation signals D1 and D2 may be compared with the values stored in advance as the demodulation signal when the gas G does not exist, or may be obtained by comparing the harmonic wave associated with the modulation and the fundamental wave.

In this way, by measuring the concentrations of acetylene and methane, respectively, the presence and extent of heating and partial discharge in the insulating oil L are detected, and OF
The deterioration of the cable 1 will be indirectly detected.

FIG. 2 shows another embodiment based on the third and fourth aspects of the present invention. In the embodiment of FIG. 2, the light emitting means 16 has a wavelength of 1.53 μm and a wavelength of 1.66.
In addition to the laser light of .mu.m, infrared laser light that does not belong to any absorption spectrum of acetylene or methane is used. For this purpose, the laser device 27 and the laser drive circuit 2
8 are installed side by side. Further, the laser devices 17, 18, 2
A laser drive circuit 19 for driving 7 based on a predetermined value,
20 and 28 have no modulation function. Therefore, three types of laser light having a constant light quantity are injected into the optical fiber 10. Further, in the embodiment of FIG. 2, the light receiving means 2
Reference numeral 2 denotes a spectroscopic device 29 which disperses a plurality of laser lights into respective wavelengths, and three photodetector devices 23, 23 and 23 which respectively convert the dissociated three kinds of laser lights into electric signals.
And are provided. Three photo detectors 23, 23, 2
3 are detection circuits 24, 25, which have no demodulation function,
It is connected to 30. These detection circuits 24, 25, 3
0 is connected to one comparison circuit 31.

In the embodiment of FIG. 2, the laser light having the wavelength of 1.53 μm and the laser light of 1.66 μm is absorbed by the gas G and attenuated in the optical transmission line 14, and another laser is emitted. Light is hardly attenuated. These laser lights are spectrally separated by the spectroscopic device 29 and processed by different photodetecting devices 23. That is, the light receiving means 22 is provided with a spectroscopic device 29 for separating and extracting light components of a single wavelength, and instead, electric modulation and demodulation are not required. Further, the infrared laser light which does not belong to any absorption spectrum of acetylene or methane is used as a reference signal for measurement, and the comparison circuit 31 compares the detection results of the respective wavelengths. Thereby, the optical fibers 10, 1
Of the optical fiber 10 forming the optical transmission line 14
(12), 11 (13) It is possible to correct the influence of transmission loss due to dirt or the like adhering to the end faces on the measurement, and it is possible to perform accurate measurement for calculating the absolute value of the gas concentration and the like.

[0039]

The present invention exhibits the following excellent effects.

(1) Since a plurality of gasses in oil can be constantly monitored, deterioration of the cable insulation can be detected early and reliably, and a cable breakdown accident can be prevented in advance.

(2) Monitoring can be automatically performed,
Human resources are saved.

(3) Since remote monitoring is possible, it is not necessary for an inspector to enter a cave or a manhole.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 OF cable 3 Connection box 9 Gas separation and capture means in oil 10, 11 Optical fiber 14 Optical transmission line 16 Light emitting means 17, 18, 27 Laser device 19, 20, 28 Laser drive circuit 21 Optical coupler 22 Light receiving means 23 Photodetector 24, 25, 30 Detection circuit 26 Transmission means 29 Spectroscopic device 31 Comparison circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shin Osawa 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Hidaka Plant (72) Inventor Nobuo Ando 3550 Kidayomachi, Tsuchiura City, Ibaraki Prefecture Address Inside Hitachi Cable's Advanced Research Center

Claims (4)

[Claims] 1. An OF case in which a conductor is coated with insulating oil.
And a gas-in-oil separation / capturing means for separating and capturing in-oil gas consisting of a plurality of components contained in the insulating oil from the insulating oil, which is attached to a connection box or the like for connecting the OF cable. An optical transmission line formed by passing through an atmosphere in which an in-oil gas composed of a plurality of components trapped in the separation capturing means is mixed, and an absorption spectrum of each of the plurality of components contained in the oil-in-gas A light emitting unit that generates lights having different matching wavelengths and that superimposes lights having these different wavelengths, and separates and extracts a light component having a single wavelength that matches the absorption spectrum from the light on which the different wavelengths are superimposed. An OF-cable insulation gas monitoring device comprising: a light-receiving means for converting; and a light-transmitting means for connecting the light-emitting means and the light-receiving means to the light-transmitting path to guide light. 2. An OF case in which a conductor is covered with insulating oil.
In the cable, an oil-in-gas separation / capturing means, which is attached to a connection box or the like for connecting the OF cable and separates and captures the in-oil gas contained in the insulating oil, and the gas-in-oil content capturing means is externally inserted. A pair of optical fibers optically provided at a predetermined interval in the gas-in-oil separation / capture means and infrared absorption spectra of a plurality of gas-in-oil separated from the insulating oil. A plurality of laser devices that generate a plurality of laser lights having equal wavelengths, and a reference signal set to a predetermined value corresponding to each of the plurality of laser lights is modulated with a different carrier frequency. A plurality of laser drive circuits for generating a modulated signal and driving the laser device by the modulated signal, and for injecting the plurality of laser lights provided at one end of the optical fiber in a superposed manner. Optical coupler and the above light A photodetector provided at the other end of the fiber for converting the plurality of laser lights into electric signals; and detecting and demodulating the electric signals at the different carrier frequencies to generate demodulated signals and from the demodulated signals. An insulating gas monitoring device for an OF cable, comprising: a plurality of detection circuits for detecting the amount of attenuation of laser light. 3. An OF case formed by coating a conductor with insulating oil.
In the cable, an in-oil gas separation / capturing means, which is attached to a connection box or the like for connecting the OF cable, separates and captures the in-oil gas contained in the insulating oil, and is inserted into the oil-in-gas separation / capturing means from the outside. A pair of optical fibers optically provided at a predetermined interval in the gas-in-oil separation / capture means and infrared absorption spectra of a plurality of gas-in-oil separated from the insulating oil. Multiple rays with equal wavelength
A plurality of laser devices that generate laser light, a laser drive circuit that drives the laser devices based on a predetermined value, and a plurality of laser lights that are provided at one end of the optical fiber. An optical coupler for superimposing and injecting, a spectroscope provided at the other end of the optical fiber for dispersing the plurality of laser lights into respective wavelengths, and an electric signal for each of the plurality of dispersed laser lights. And a plurality of photodetectors for converting the laser light into a plurality of photodetectors, and a plurality of detector circuits for detecting the amount of attenuation of each laser light from the electric signal. .. 4. A laser device which is provided in parallel with the plurality of laser devices and generates a reference laser light having a wavelength that is not absorbed by a plurality of gasses in oil separated from the insulating oil. A photodetector for converting the reference laser light dispersed by the spectroscopic device into an electric signal, an electric signal converted from the plurality of laser lights, and an electric signal converted from the reference laser light 4. An OF-cable gas monitoring device in an OF cable according to claim 3, further comprising: a comparison circuit for detecting the attenuation amount of each laser light by comparing with the above.