WO2005073702A1

WO2005073702A1 - Decomposed gas sensor for gas-insulated apparatus, insulating gas decomposition detector, and decomposed gas detecting method

Info

Publication number: WO2005073702A1
Application number: PCT/JP2005/001234
Authority: WO
Inventors: Junya Suehiro
Original assignee: Kyushu Tlo Company, Limited
Priority date: 2004-01-29
Filing date: 2005-01-28
Publication date: 2005-08-11
Also published as: JP2005214788A; JP4500993B2

Abstract

A decomposed gas sensor for gas-insulated apparatuses responds to a decomposed gas of an insulating gas with high sensitivity and at high speed and is easily produced at low cost. An insulating gas decomposition detector for detecting decomposition and a decomposed gas detecting method are also disclosed. A decomposed gas sensor (1) for gas-insulated apparatuses for detecting a decomposed gas of the insulating gas sealed in a high-voltage electric apparatus. The decomposed gas sensor (1) is characterized mainly in that it comprises a detecting unit made of a semiconductor carbon nano material (2), and when a decomposed gas is adsorbed on the semiconductor carbon nano material (2) and reacts, the detection unit outputs an impedance variation.

Description

Specification

Decomposition gas sensor for gas insulation equipment, insulation gas decomposition detection device, and decomposition gas detection method

Technical field

The present invention provides an inexpensive, high-speed response, high-accuracy detection, and easy-to-manufacture decomposition gas sensor for gas-insulated equipment of a carbon nano material, and installing the decomposition gas sensor at a plurality of locations to determine the generation position of the decomposition gas. The present invention relates to an insulation gas decomposition detection device capable of detection and a method for detecting a decomposition gas of an insulating gas.

Background art

[0002] Since the late 1960s, sulfur hexafluoride gas (hereinafter referred to as SF gas) with excellent insulation properties has been used as substation equipment.

6) Gas-insulated switchgear (GIS), gas circuit breaker (GCB), etc. in which gas-filled switches are enclosed are being introduced. SF gas is equal

6

It is a non-toxic, odorless, and inert gas that has insulation resistance about three times that of air at the same pressure in an electric field. This substation equipment needs to be subjected to equipment diagnosis, for example, equipment diagnosis for partial discharge and ground fault, etc. This diagnosis is indispensable especially for equipment that has been used for a long time after introduction. In order to detect the occurrence of partial discharge, etc. in such equipment diagnosis, a detection tube (gas checker) that can detect the decomposition gas in which SF has been decomposed by discharge has been used.

6

. However, it is difficult to detect partial discharges in real time using detector tubes, which have poor quantitativeness and sensitivity. Not available for online control. It becomes detectable only when the partial discharge spreads. The management had to be kept in the refrigerator, which was disposable and costly. Therefore, SF decomposition using solid electrolyte

6 A gas sensor has been proposed (see Patent Document 1).

[0003] This SF decomposition gas sensor has a detection electrode, a fluorine ion conductive solid electrolyte, a counter electrode,

6

It consists of electrodes, and both electrodes are provided in close contact with a solid electrolyte interposed therebetween. When performing detection, install in the atmosphere of the gas to be detected so that the detection electrode contacts the SF decomposition gas, and perform the detection.

6

A DC voltage is applied between the output electrode and the counter electrode. The application of this DC voltage causes an electrode reaction at the detection electrode to electrolyze the fluorine-containing gas, which is generated by the electrolysis at this time. The current based on the electromotive voltage is detected as a signal output by an ammeter, and the concentration of fluorine-containing gas is known from the current value. However, this SF decomposition gas sensor has a large variation in reaction sensitivity.

6

Due to lack of reliability, the sensitivity was limited to about 0.2 ppm. There was also a weak point that force and response were slow. Therefore, it was difficult to detect partial discharge at an early stage by the gas detector using the solid electrolyte.

[0004] In addition, there has been proposed a technique for detecting a partial discharge by utilizing leakage of an electromagnetic wave to the outside when a partial discharge occurs in a GIS (see Patent Document 2). In this method, a leaked electromagnetic wave is detected by an antenna, passed through a bandpass filter, compared with a comparator after amplification, and a buzzer or the like is sounded when the reference level is exceeded. However, there was a high possibility that erroneous judgments would occur in substation equipment because noise was likely to occur.

[0005] As described above, many types of sensors for detecting the decomposition of insulating gas of high-voltage electrical equipment have been proposed, but a sensor with high sensitivity and high reliability has not yet been proposed. In addition, since such high-sensitivity sensors do not exist, the decomposition gas generated only in a very small amount in the GIS actually has what composition and what kind of reaction occurs in partial discharge etc. There is a situation in which the power has risen and the power of the power has been poorly understood.

[0006] In recent years, research on carbon nanotubes has attracted attention for applying carbon nanotubes (hereinafter, CNT) to gas sensors. When gas molecules are adsorbed on semiconductor CNTs, charge transfer occurs between them and the electrical characteristics (conductance, capacitance) of the semiconductor CNTs change. The CNT gas sensor detects gas using this phenomenon. However, among the gases, only the gas that transfers a large amount of charge to and from the semiconductor CNT is actually effective as a sensor. Currently, only a few types of gases, such as NH, N〇, steam, ethanol, C〇, CO, and CH, have been reported to be detectable by CNT.

3 2 2 6 6

Absent.

[0007] However, regarding the structure of the CNT sensor, since such difficulties are relatively small, for example, a CNT sensor in which a large number of semiconductor CNTs are directly grown on a sensor electrode or a large number of semiconductor CNTs generated in advance are dispersed in a solvent. There has been proposed a CNT sensor or the like which is applied between electrodes, dried and randomly integrated (see Patent Document 3). However, since both sensors cannot freely manipulate nanosized semiconductor CNTs, they are directly grown on electrodes and coated. ing.

[0008] As a method of operating such a minute object, the present inventor has conventionally proposed a DEPIM (Dielectrophoretic Impedance Measurement Method) method for producing a minute object such as a microorganism (Patent Document 4). In the DEPIM method, a minute object polarized by an uneven electric field is collected on a microelectrode by electrophoretic force.

Patent Document 1: Japanese Patent Application Laid-Open No. 2003-66001

Patent Document 2: Japanese Patent Application Laid-Open No. 2002-116235

Patent Document 3: Japanese Patent Application Laid-Open No. 2003-227808

Patent Document 4: JP-A-2003-224

Disclosure of the invention

Problems to be solved by the invention

[0010] As described above, some sensors have been proposed as sensors for detecting the decomposition of insulating gas in high-voltage electrical equipment. However, gas sensors with high sensitivity and high reliability that are easy to manufacture are proposed. Not yet proposed. Since such a sensor does not exist, the composition of the decomposed gas, which is generated only in a very small amount, is actually what kind of reaction occurs due to partial discharge in high-voltage electrical equipment. The power of the power is not fully understood.

[0011] The SF decomposition gas sensor, one of the proposals, uses raw materials and raw materials in the production process.

6

Even if the production process is adequately controlled, large variations occur in performance, especially in the sensitivity to hydrogen fluoride gas at a certain concentration. Since this variation is unavoidable in production, the amount of fluorine gas cannot be accurately measured until that time, and the production yield is extremely low in order to obtain a reaction sensitivity that passes the standard. Therefore, it is not possible to perform system control that delays difficult responses such as detection of the location where partial discharge occurs. In addition, sensors that detect electromagnetic waves also make erroneous decisions due to noise, and there is a limit to obtaining a sensor with high sensitivity and high reliability.

[0012] Further, it is not clear whether or not the semiconductor CNT can detect the decomposition gas of the insulating gas and whether or not the semiconductor CNT can output at a higher sensitivity than other gas sensors. Regarding the manufacture of semiconductor CNT sensors, conventional CNT gas sensors are not easy to manufacture and costly. The In addition, the CNT gas sensor in which CNTs generated in advance are dispersed and applied in a solvent has a problem that the directions of the CNTs are random and uneven, so that there is much variation and accurate detection cannot be performed.

[0013] Accordingly, an object of the present invention is to provide a low-cost, easy-to-manufacture decomposed gas sensor for gas-insulated equipment that responds to decomposed gas of insulating gas with high sensitivity and high speed.

[0014] Another object of the present invention is to provide a highly sensitive and inexpensive insulating gas decomposition detection device that can immediately identify the position of an insulating gas when the insulating gas is decomposed by partial discharge or the like in a high-voltage electric device. I do.

[0015] An object of the present invention is to provide a method for detecting a decomposition gas that responds to a decomposition gas of an insulating gas with high sensitivity and high speed.

Means for solving the problem

[0016] The present invention is a decomposed gas sensor for a gas insulated device capable of detecting a decomposed gas of an insulated gas sealed in a high-voltage electric device, comprising: a detection unit made of a semiconductor carbon nano material; The main feature is that the detector outputs impedance change by adsorbing and reacting with the semiconductor carbon nanomaterial.

The invention's effect

According to the decomposed gas sensor for a gas insulated device of the present invention, it responds to the decomposed gas of the insulating gas with high sensitivity and high speed, is inexpensive, and is easy to manufacture. Further, according to the insulating gas decomposition detection device of the present invention, when the insulating gas is decomposed in the high-voltage electric device, the position can be immediately specified. According to the decomposition gas detection method of the present invention, it is possible to respond with high sensitivity and high speed.

Brief Description of Drawings

FIG. 1 is an explanatory view of a decomposed gas sensor for a gas insulated device according to a first embodiment of the present invention.

FIG. 2 is a schematic view of a carbon nanomaterial integrated between electrodes by dielectrophoresis in the present invention observed by scanning electron microscope (SEM).

FIG. 3 is a graph showing the temperature dependence of the conductance of the integrated carbon nanomaterial according to the present invention.

(FIG. 4) (a) A gas was installed by mounting the decomposition gas sensor for gas-insulated equipment in Example 1 of the present invention. Configuration diagram of the gas measurement device to be detected, (b) Explanatory diagram in which a plurality of decomposition gas sensors for gas insulation equipment are installed in the gas measurement device in (a)

FIG. 5 is an explanatory view of a cracked gas generation simulation device according to Embodiment 1 of the present invention.

FIG. 6 shows a change with time of conductance with respect to discharge generated in SF in the present invention.

6

Graph

FIG. 7 (a) shows a change in conductance of the carbon nanomaterial according to the present invention with respect to NH.

Three

Graph, (b) Capacity of integrated carbon nanomaterial in the present invention for NH

Three

Graph showing the change in the distance

FIG. 8 (a) shows a change in conductance of carbon nanomaterial to NO in the present invention.

2

Graph, (b) Change in capacitance of carbon nanomaterial to NO in the present invention

2

Graph showing

[FIG. 9] (a) Relationship between NH conductance change and concentration of carbon nanomaterial in the present invention

Three

A graph showing the relationship, (b) a change in the conductance of NO of the carbon nanomaterial in the present invention.

2

Graph showing the relationship between density and concentration

[Fig. 10] Comparison of response between the cracked gas sensor for gas insulation equipment and the HF detector tube according to the present invention.

[FIG. 11] A response comparison between a decomposition gas sensor for gas insulation equipment and an SO detection tube according to the present invention.

2

H

[FIG. 12] The emission of carbon nanomaterials in the present invention in SF gas, N gas and air

6 2

Graph showing the change in conductance with respect to electricity

FIG. 13 is a graph of a change with time during discharge measured at each point from the electrode of the present invention.

FIG. 14 is a configuration diagram of a gas sensor manufacturing apparatus according to Embodiment 1 of the present invention.

Explanation of symbols

1 Decomposition gas sensor for gas insulation equipment

la, lb electrode

2 Carbon nanomaterial

3a, 3b Edge for electric field concentration

4 Insulating board 5a, 5b connection terminal

6 Gas measurement device

6a Gas measurement / dielectrophoresis controller

7 Device to be detected

11, 21 Power supply

12, 22 Measuring unit

13, 23 Operation control unit

14, 24 Display

15, 25 Memo part

15a Calibration data section

16, 26 timekeeping 咅 B

25a Data section

27 Electrophoresis chamber

28 Contents

29 pump

30 Stirrer

31, 32 Solenoid valve

41 electrodes

42 High voltage power supply

BEST MODE FOR CARRYING OUT THE INVENTION

A first aspect of the present invention is a decomposition gas sensor for a gas insulating device capable of detecting a decomposition gas of an insulating gas sealed in a high-voltage electric device, wherein the detection unit comprises a semiconductor carbon nano material. This is a decomposed gas sensor for gas insulated equipment that outputs the change in impedance of the detection unit resulting from the reaction of the decomposed gas to the semiconductor carbon nanomaterial as it reacts.It can be used at room temperature, has high sensitivity, and has extremely fast response. It is easy, inexpensive, small, easily obtains electrical output, and can be used repeatedly.

A second aspect of the present invention is the decomposition gas sensor for gas insulated equipment according to the first aspect, wherein the insulating gas is any one of (1) SF gas, (2) nitrogen gas, and (3) air. Mainly one kind A mixture of two or more gases, or a mixture of two or more gases containing an insulating gas other than (1), (2), and (3), and the detection unit decomposes the gas. A gas detection gas sensor for insulating equipment that can detect gas, which is not normally generated, locally and with high sensitivity.

6 6 2, gas mixture with CO gas, etc.

2

In many cases, nitrogen gas, air, etc. are sealed, but such abnormalities in GIS etc. can be easily detected in advance.

A third mode of the present invention is a mode subordinate to the first mode or the second mode, and is a decomposition gas sensor for gas insulated equipment that outputs a change in conductance as a change in impedance, and has a high sensitivity and extremely high response. It can be a fast sensor.

A fourth mode of the present invention is a mode dependent on the first mode or the second mode, and is a decomposition gas sensor for a gas insulated device that outputs a capacitance change as an impedance change, and is similar to an output of a conductance change. A highly sensitive and extremely fast sensor can be obtained.

A fifth aspect of the present invention is a form dependent on any one of the first to fourteenth aspects, wherein the semiconductor carbon nanomaterial has a pair of electrodes, and a detection unit is bridged between the electrodes. This is a decomposition gas sensor for gas insulated equipment, which responds at high speed by the cross-linked structure of carbon nanomaterial, and has high detection accuracy. It can be used at room temperature, is highly sensitive, has a fast response, is easy to manufacture and is inexpensive, can easily obtain an electrical output, and can be used repeatedly.

[0025] A sixth aspect of the present invention is a form subordinate to the fifth aspect, wherein the electrode is provided with an electric field concentration edge for generating an uneven electric field when an AC voltage is applied, and the detection unit is a dielectrophoretic device. This is a decomposed gas sensor for gas insulation equipment formed by the method described above.Electrodynamically operated by dielectrophoresis by providing an electric field concentration edge on the electrode, it can be manufactured at low cost, and the carbon nanomaterial is oriented in the direction of the electric field. Basically, this cross-linked structure provides a high-speed response and high detection accuracy.

A seventh aspect of the present invention is a form subordinate to the sixth aspect, wherein the electrode is a thin-film electrode provided on an insulating substrate, and an edge for electric field concentration is provided on each of the electrodes. This is a decomposition gas sensor for gas insulated equipment, which is the edge of the formed protrusion. Can be manufactured easily.

An eighth aspect of the present invention is a decomposition gas sensor for a gas insulated device, which is a form subordinate to any one of the first to seventeenth aspects, and is a semiconductor carbon nanomaterial 材料 type semiconductor. The conductance decreases for reducing gases and increases for oxidizing gases.

[0028] A ninth aspect of the present invention is a decomposition gas sensor for a gas-insulated device, wherein the semiconductor carbon nanomaterial is an n-type semiconductor, which is a form subordinate to any one of the first to seventeenth aspects. The conductance increases for reducing gases and decreases for oxidizing gases.

[0029] A tenth aspect of the present invention is a decomposition gas sensor for a gas insulated equipment, which is disposed in an insulating gas of a high-voltage electric device in a plurality of positions, and a decomposed gas sensor for a gas insulated equipment. A power supply for applying a voltage to each of the sensors, a measuring unit for detecting a change in impedance of each of the decomposition gas sensors for each gas-insulated device when the voltage is applied, and a change in the impedance detected by the measuring unit to a predetermined reference value. A control section for comparing, and the control section determines the position of the cracked gas sensor for gas insulation equipment that has output an impedance change equal to or greater than the reference value as the position at which the cracked gas is generated. It is a device that can respond to cracked gas with high sensitivity and high speed, and can be installed at multiple locations to detect the location of cracked gas generation, and to detect abnormalities in high-voltage electrical equipment. The ability to discover in advance S

[0030] In an eleventh aspect of the present invention, a decomposed gas sensor for a gas insulated device including a detection unit made of a semiconductor carbon nano material is disposed in an insulating gas of a high-voltage electric device, and a decomposed gas generated from the insulating gas is provided. Is a method for detecting cracked gas by changing the impedance of the detection section to detect cracked gas.The method can respond to cracked gas with high sensitivity and high speed. Output can be obtained, and the power can be repeatedly used.

Example

Hereinafter, a decomposition gas sensor for a gas insulation device, an insulation gas decomposition detection device, and a decomposition gas detection method according to a first embodiment of the present invention will be described. This decomposition gas sensor for gas insulation equipment, Insulating gas decomposition detection equipment can detect unusual decomposition gas as soon as it is generated, and can detect abnormalities that have occurred locally in GIS etc. before they spread to the whole. Since a plurality of decomposed gas sensors for gas-insulated equipment are distributed and arranged in the GIS, decomposed gas sensors for gas-insulated equipment installed near partial discharges etc. can detect them and detect partial discharges etc. at an early stage. It is.

FIG. 1 is an explanatory view of a decomposed gas sensor for a gas-insulated device in Example 1 of the present invention, FIG. 2 is an SEM photograph of carbon nanomaterials integrated between electrodes by dielectrophoresis in the present invention, and FIG. FIG. 4A is a graph showing the temperature dependence of the conductance of the integrated carbon nanomaterial according to the present invention, and FIG. 4A is a configuration of a gas measuring apparatus for detecting a gas by mounting the decomposition gas sensor for a gas insulating device according to the first embodiment of the present invention. Fig. 4 (b) is an explanatory view of installing a plurality of decomposed gas sensors for gas insulating equipment in the gas measuring apparatus of (a), and Fig. 5 is an explanatory view of a decomposed gas generation simulating apparatus in Example 1 of the present invention. . Fig. 6 shows the results in SF in the present invention.

6 A graph showing the change over time in the conductance with respect to the generated discharge, FIG. 7 (a) is a graph showing the change in the conductance of the carbon nanomaterial to NH in the present invention, and FIG.

Three

Fig. 4 shows the change in capacitance of integrated carbon nanomaterial with respect to NH in the invention.

Three

Fig. 8 (a) shows the conductance of carbon nanomaterial to NO in the present invention.

2

FIG. 8 (b) is a graph showing the change, and FIG.

2

FIG. 9 (a) is a graph showing the change in pacitance, and FIG.

3 A graph showing the relationship between the change in conductance and the concentration, and FIG. 9 (b) is a graph showing the relationship between the change in the conductance of NO in the carbon nanomaterial and the concentration in the present invention. Figure 1

2

0 is a response comparison graph of the cracked gas sensor for gas-insulated equipment and the HF detector tube of the present invention, and FIG. 11 is a response ratio of the cracked gas sensor for gas-insulated equipment and the s〇 gas sensor of the present invention.

2

FIG. 12 shows the carbon nanomaterial of the present invention in SF gas, N gas, and air.

6 2

FIG. 13 is a graph showing the change in conductance with respect to the generated discharge, FIG. 13 is a graph showing the change over time during discharge measured at each point from the electrode of the present invention, and FIG. 14 is a configuration diagram of the gas sensor manufacturing apparatus in Example 1 of the present invention. It is.

[0033] In Fig. 1, reference numeral 1 denotes SF gas, N gas, and air enclosed in high-voltage electrical equipment such as GIS.

6 Chip-shaped decomposition gas sensor for gas-insulated equipment to detect decomposition gas such as 2 and la, lb Is a pair of electrodes that constitute a disassembled gas sensor for gas-insulated equipment having a shape such as a castle wall-type electrode or comb-tooth-type electrode.1 is a pair of electrodes such as CNT, carbon nanohorn, carbon nano-one, carbon nanofiber, and fullerene. Semiconductor carbon nanomaterial (hereinafter, carbon nanomaterial), 3a and 3b are electric field concentration edges such as bent edges (hereinafter, edges) that generate uneven electric fields that enable dielectrophoresis, and 4 is insulating The substrates 5a and 5b are connection terminals for the electrodes la and lb. The carbon nanomaterial 2 corresponds to the detection unit in the first embodiment of the present invention.

[0034] The insulating gas is SF gas in Example 1, but is used in GIS and the like.

6

The above-mentioned N gas, air, and mixed gas of SF gas and N gas and / or C〇 gas etc.

2 62 2 gas. Therefore, one of SF gas, N gas and air, or this one as the main component

6 2

Or a mixture of SF gas and N gas and / or CO gas

6 2 2

Gases such as N2 and CO gas, such as gas, can be used as insulating gas.

twenty two

[0035] However, what kind of reaction and what composition the decomposition gas of such an insulating gas is generated by partial discharge or the like has been sufficiently clarified experimentally and theoretically at present. Not. Therefore, accurate explanations that support the decomposition gas are difficult to explain only for the outline, but it is assumed that the decomposition gas of SF gas is as follows.

6

Is done. The first is the gas generated by the reaction between SF gas and metal, the second is the reaction with moisture

6

Is the gas generated by The first reaction varies depending on the metal of the partner, but for example, SF + Cu → SF + CuF, 3SF + W → WF + 3SF, etc. can be considered. Second reaction

6 4 2 6 6 4

For example, SF + H〇 → SOF + 2HF, SOF + H0 → SO + 2HF

4 2 2 2 2 2

. Therefore, the decomposition gas of SF gas includes gases such as SOF, HF, SF, SO, etc.

6 2 4 2

It is speculated that When the insulating gas is N gas or air, the components such as 〇, N〇, N〇

2 3 2

It is thought to form degassed gas.

Next, the carbon nanomaterial 2 in Example 1 will be described. The force nanomaterial 2 used in the present invention is a general term for carbon nanotubes (CNT), carbon nanohorns, carbon nano onions, carbon nanofibers, fullerenes, etc., and various carbon atoms including spherical, cylindrical, conical, etc. It refers to all substances that combine in shape to form a structure on the nanometer (Ιθη) scale. Note that “nano” is simply This is a name when attention is paid to the position, and even if a plurality of these are in a micron scale ( ^10_b m) state due to aggregation or the like, they can be included in the carbon nanomaterial 2. The main constituent element is carbon, but a substance containing an element other than carbon is also included in the carbon nanomaterial for the purpose of controlling its structure and physical properties. The carbon nanomaterial 2 is mixed with a solvent such as ethanol, and an alternating voltage is applied to the electrodes la and lb in the suspension, and the electric field intensity is the highest among the uneven electric fields generated by this. It is integrated by electrophoresis between the growing electric field concentration edges 3a and 3b. The production method by dielectrophoresis will be described later in detail. After the accumulation, the solvent is evaporated and physically adsorbed on the insulating substrate 4 in a crosslinked state (see the photograph in FIG. 2). According to the experiment, the carbon nanomaterial 2 shows temperature dependence as shown in FIG. 3, and although not shown, the voltage-current characteristic also has non-linearity, and has properties as a semiconductor. I have. It is known that the carbon nanomaterial 2 exhibiting semiconductivity has a p-type in which a main current carrier is a hole and an n-type in which an electron is an electron, similarly to a silicon semiconductor. Which type is used can be controlled by the structure of the carbon nanomaterial and the doping of other elements. For example, an n-type semiconductor can be obtained by doping with K or Rb. The carbon nanomaterial 2 may be manufactured by any manufacturing method such as a CVD method and a thermal decomposition method. When carbon nanomaterials can be grown directly on electrodes la and lb by these methods, integration by dielectrophoresis is not always necessary. Decomposed gas such as SF gas is placed on the surface of the aggregate of such carbon nanomaterials 2.

6

Adsorbs and exchanges electrons, and appears as an impedance change between the electrodes la and lb. Note that an aggregate of the carbon nanomaterials 2 corresponds to the detection unit of the present invention.

Explaining the electrodes la and lb, the castle wall type electrode shown in Fig. 1 has a large number of rectangular projections formed at every other pitch (for example, 50 μm-100 μm) on the sides of the electrodes la and lb facing each other. They are arranged at a distance of one pitch from each other, for example, at a distance of 5 xm-10 zm. The edges of the protruding portions of the electrodes la and lb are the electric field concentration edges 3a and 3b, and the electric field is particularly concentrated between the electric field concentration edges 3a and 3b. Many shapes, such as a comb shape and a saw-tooth shape, are not limited to a rectangular shape. Note that a comb-shaped comb-shaped electrode has a pair of electrodes having teeth (for example, 30 μηι-μm width) formed like a comb and nested in a groove and combined with each other to form a narrow gap ( For example, electrodes facing each other at 5 xm—10 zm width An unequal electric field is mainly formed between edges in the thickness direction, whereby a large number of carbon nanomaterials 2 are integrated.

[0038] The electrodes la and lb are formed as thin-film electrodes of chromium, platinum, or the like, formed on an insulating substrate 4 of glass, plastic, silicon oxide, or the like by sputtering, vapor deposition, plating, or the like, and then etched by photolithography or the like. Formed. It is desirable that the thickness of the thin film be about 50 nm to 200 nm. The materials of the electrodes la and lb are not limited to chromium and platinum. Electrolytic decomposition does not occur when an AC voltage is applied, and metals with a low ionization tendency can be used. When a large number of identical gas sensors are installed as in the insulated gas decomposition detection device of the present invention, it is preferable to provide a dedicated connection terminal that can be connected to the connection terminals 5a and 5b.

Subsequently, when the insulating gas is decomposed due to partial discharge or the like in the high-voltage electrical equipment, the decomposition position can be immediately specified by using a plurality of the above-mentioned decomposed gas sensors 1 for gas insulating equipment. The gas decomposition detection device will be described with reference to FIGS. In Fig. 4 (a), 6 is a gas measuring device of an isolated gas decomposition detection device that detects a decomposition gas by installing a decomposition gas sensor 1 for gas insulation equipment, and 7 is a gas detector that detects the decomposition gas with a gas measurement device 6. AC or DC high-voltage electrical equipment such as AC and GCB. As shown in FIG. 4 (b), the decomposition gas sensor 1 for gas insulated equipment includes a large number of decomposition gas sensors 1 for gas insulated equipment. In addition, the gas measuring device 6 of Example 1 can be used as it is for a carbon nano material swimming device that performs dielectrophoresis of the carbon nano material 2 at the time of producing the decomposition gas sensor 1 for gas insulation equipment that can be used only at the time of measurement. It is.

[0040] Reference numeral 11 denotes a power supply unit that applies an AC voltage for measurement between the electrodes la and lb, 12 denotes a measurement unit that can measure the impedance between the electrodes la and lb, and 13 includes a microprocessor and the like, and includes a program. Control unit (control unit of the present invention) that functions by reading data and data and controls at least the power supply unit 11 and the measurement unit 12, 14 is a display unit, 15 is a memory unit that stores programs and data Reference numeral 15a denotes a calibration data section storing calibration data of the change in conductance of the decomposition gas, and 16 denotes a clock section. The power supply unit 11 is a DC or AC power supply, and the voltage and frequency are controlled by the arithmetic and control unit 13. In the first embodiment, the voltage amplitude IV can be adjusted to 10 V, and in the case of AC, the frequency can be further adjusted to 1 kHz to 10 MHz. In the first embodiment, a sine wave is applied as an AC voltage, but is substantially constant. Means the voltage of the triangular wave, square wave, etc., which changes the direction of the flow in the cycle of, and the average value of the current on both the positive and negative sides is equal.

The measuring unit 12 is provided with a current detecting resistor of about lk Q, and is connected in series to the voltage application circuit shown in FIG. 4 (a). The impedance between electrodes la and lb is calculated in real time by measuring the phase difference between the two. As a result, the conductance component (the reciprocal of resistance) and the capacitance component of the impedance change generated by the reaction of the carbon nanomaterial 2 with the decomposition gas are calculated. As will be described later, either the conductance or the capacitance may be used to detect the decomposition gas.In Example 1, however, the case where the capacitance is not used and the detection by the conductance is performed will be described. . On the other hand, when a DC voltage is used, only the magnitude of the current is measured by the resistance for current detection, and the conductance between the electrodes la and lb is calculated in real time. Using the conductance thus measured, the gas concentration is obtained from the calibration data in the calibration data section 15a.

[0042] Actually, the measured value of the conductance detected by the measuring unit 12 fluctuates, and a fluctuation exceeding the limit means generation of a decomposition gas. Therefore, a reference value which is a limit of the impedance change (in this case, the conductance change) when partial discharge can be confirmed is obtained in advance and stored in the memory unit 15. The detected impedance change is compared with the reference value, and when the reference value is exceeded, it is determined that decomposition gas has been generated.

By the way, in the insulating gas decomposition detection apparatus according to the first embodiment, a plurality of decomposition gas sensors 1 for gas insulation equipment are arranged at predetermined intervals in a container of a high-voltage electric equipment as shown in FIG. 4 (b). In FIG. 4 (b), decomposition gas sensors 1 for gas insulation equipment are arranged at several points, such as points A, B, C,. Decomposition gas detection is continued at points A, B, C, etc., and at some point, the deviation force, the impedance change measured at one point, for example, point A, exceeds the reference value. Then, the arithmetic and control unit 13 determines that a partial discharge or the like has occurred in the vicinity of the point A, and notifies the display unit 14 or a notifying means such as a buzzer (not shown) of the abnormality. As a result, abnormalities such as partial discharge occurring in high-voltage electrical equipment can be immediately avoided.

The above description relates to the configuration of the decomposition gas sensor 1 for gas insulation equipment and the configuration of the insulation gas decomposition detection device. Hereinafter, the operation when the decomposition gas sensor 1 for gas insulation equipment detects the decomposition gas will be described. Since the measurement of cracked gas is difficult with an actual machine, the measurement is performed using the cracked gas generation simulator shown in Fig. 5. In Fig. 5, 7a is a gas-filled tank, 41 is a corona discharge electrode that simulates partial discharge, discharge due to ground fault or short circuit, and 42 is a 60Hz high voltage power supply for discharging from electrode 41. Department. Decomposed gas sensors 1 for gas insulation equipment are provided at points A, B, and C at different distances from the corona discharge electrode. The high-voltage power supply unit 42 can adjust the voltage between 10 kV and 50 kV. Fig. 6 shows the force S, which is the time-dependent change in conductance at point A when discharging at the electrode 41, and the period (period) A is the period during which the voltage supplied from the high-voltage power supply 42 to the electrode 41 is 〇N, and the period (period) ) B represents a period in which the voltage supplied to the electrode 41 is turned off, and period (period) C represents a period in which the voltage supplied to the electrode 41 is ΔN. It can be seen that the higher the discharge voltage is, the higher the conductance of the disassembled gas sensor 1 for each gas insulating device is.

When the insulating gas is decomposed, a decomposed gas containing various oxidizing or reducing gases is generated. The composition differs for each insulating gas. Therefore, if at least a gas showing oxidizing or reducing properties can be detected, the decomposed gas sensor 1 for gas insulated equipment can detect the generation of decomposed gas. Therefore, in order to measure the decomposition gas whose composition is not clear, the oxidizing gas and the reducing gas whose properties are clearly measured are measured in advance, and the response and output as a reference for determining the power of the oxidizing gas or the reducing gas. You have to know.

[0046] This measurement is performed on lOppm of NH (reducing gas) and NO (oxidizing gas) at room temperature.

3 2

It was. A high frequency sine wave voltage with a frequency of 100 kHz and an amplitude of 4 V was applied to the decomposition gas sensor 1 for gas insulation equipment. Ar is housed in the chamber as an initial state, and NH is used for measurement.

Replace with 3 or N〇.

2

At this time, as shown in FIGS. 7 (a) and (b), and FIGS. 8 (a) and (b), the conductance of NH sharply decreases.

Three

On the contrary, the capacitance rises sharply. On the other hand, with NO, the conductance is

2

Increases and the capacitance decreases. This is probably because the carbon nanomaterial 2 is a p-type semiconductor. That is, when the reducing NH molecules are adsorbed on the carbon nanomaterial 2,

Three

Electrons move from the NH molecule to the carbon nanomaterial 2, and the hole density of the carbon nanomaterial 2

Three

, Which leads to lower conductance and higher capacitance. In contrast When the oxidizing NO molecules are adsorbed, electrons move from the carbon nanomaterial 2 to NO, and

This is because the density of the conductor increases, the conductance increases, and the capacitance decreases. An n-type semiconductor is considered to show the opposite tendency.

As described above, when the p-type semiconductor carbon nanomaterial 2 is used, the conductance increases when the decomposition gas is an oxidizing gas, and the conductance decreases when the decomposition gas is a reducing gas. Although a change in capacitance can be used, it is preferable to measure a change in conductance because of the presence of stray capacitance and the like. Therefore, although both are described as impedance changes, the following description focuses on conductance changes.

[0049] Further, the same measurement is repeated while changing the gas concentration, and the relationship between the conductance change until the conductance saturates in a stable state and the gas concentration is obtained. By using this as a calibration curve as shown in FIG. By measuring the change in conductance, it can be converted into a gas concentration. Note that N〇

In Fig. 2, since the conductance does not saturate, data after 9 minutes, which can be considered as stabilized after gas introduction, is used as an alternative value (see Figs. 8 (a) and (b)). Detection lower limit is NO force SlOppb

2

, NH power is OOppb.

Three

[0050] Therefore, when the decomposition gas is detected with the carbon nanomaterial 2 of the p-type semiconductor, if the conductance decreases, it indicates that the reducing gas is strong and the decomposition gas is generated, and if the conductance increases. Indicates that a decomposition gas having a strong oxidizing power was generated. Also, by measuring the conductance change at a predetermined time such as saturation, it can be seen that the gas concentration can be calculated from the calibration curve in FIG.

Next, using the cracked gas generation simulation device shown in FIG. 5 and the cracked gas sensor 1 for gas insulation equipment, one of the insulating gases (1) SF gas, (2) N gas, and (3) air Discharge within

6 2

The change in the conductance of the decomposition gas generated when this is performed will be described. In the experiment, the tank 7a of the decomposition gas generation simulator and the electrode 41 were used, (1) SF gas, (2) N gas, and (3) air

6 2

Each insulating gas was sealed at room temperature, and discharged by the electrode 41 to detect a decomposed gas. Among them, (1) when detecting SF gas, the same as decomposition gas sensor 1 for gas insulation equipment

6

In addition, the HF detector tube (gas checker) and the S〇 detector tube are used to detect HF and S〇 in the decomposition gas.

22 I made a knowledge and compared.

[0052] Fig. 10 shows the results of both the decomposition gas sensor 1 for gas insulation equipment and the HF detector tube. It is. As shown in FIG. 10, the decomposed gas sensor 1 for gas insulated equipment immediately responds to a weak discharge near the corona start voltage (effective value: 9 kV). Power that continued to discharge for about 1.2 hours thereafter The HF detector tube did not respond. After that, once lower the voltage, SF gas

When the applied voltage was increased to 30 kV to promote the decomposition of 6, the decomposition gas sensor 1 for gas-insulated equipment immediately started the reaction and changed to about 10 times the initial conductance change. In response to this discharge, the HF detector tube remained unresponsive for a long time, and responded only after 2 hours, when the decomposition gas increased considerably.

[0053] At this time, the response of the decomposed gas sensor 1 for gas-insulated equipment was a conductance change A G = 3 µs, and the HF concentration detected by the HF detector tube was about 1.8 ppm. Since the measurement accuracy of the conductance of this measuring device is 1 μS, the decomposition gas sensor for gas insulation equipment 1 detects oxidized decomposition gas generated simultaneously with HF with a gas concentration of 1.8 ppm / 30 = 0.06 ppm = 60 ppb. See what you can do. Thus, when converted to HF, it is considered possible to detect decomposed gases on the order of ppb (several ppb or more, at least lOppb).

Similarly, according to FIG. 11, the decomposition gas sensor 1 for gas insulation equipment immediately reacts near the corona start voltage (effective value: 9 kV). 1. SO detection even when discharging for about 5 hours

2 Tubes do not react. Then, when the applied voltage was lowered and increased to 30 kV again, the decomposition gas sensor for gas-insulated equipment 1 immediately reacted and changed to about 10 times the initial change in conductance. The SO detector tube remains non-responsive for a long time, and responds two hours after the decomposition gas increases.

2

I am responding.

[0055] At this time, the response of the decomposed gas sensor 1 for gas insulation equipment is A G = 45 / i S,

2 The SO concentration detected by the Shiretoko was about 1.2 ppm. Since the measurement accuracy is l S,

2

It can be seen that the decomposed gas sensor 1 for gas insulation equipment was able to detect oxidized decomposed gas generated simultaneously with S〇 at a gas concentration of 1.2 ppm / 45 = 0.02 ppm = 20 ppb. Thus, SO

2

When converted to, it is considered possible to detect a gas concentration of about lppb.

2

[0056] Further, Fig. 12 shows the change in conductance for (1) SF gas, (2) N gas, and (3) air.

6 2

These are shown in comparison. Applied voltage l lkV for SF gas, 8k for N gas

6 2

LlkV is applied to V and air. According to the results in Fig. 12, the SF gas conductor

6

The conductance change is the lowest, but the conductance change of N gas and air decomposition gas is also a positive change. It has a similar shape. Therefore, it is generated by discharge in N gas and air.

2

The decomposed gas is oxidizing, just like the decomposed gas generated by the discharge in SF gas.

6

If the calibration curve is created, the gas concentration can be calculated by measuring the change in conductance. Similarly, (1) SF gas, (2) N gas, (3) air insulation

6 2

An insulating gas containing one type of gas as a main component and another gas as a subcomponent, or an insulating gas such as N gas or C〇 gas as a subcomponent, is included in this Mixed

twenty two

Even in such a case, the detection and the calculation of the concentration can be similarly performed.

By the way, as shown in points A, B and C in FIG. 4 (b), the insulation gas decomposition detection device has a plurality of decomposition gas sensors 1 for gas insulation equipment arranged in the insulation gas of a high-pressure electric equipment. Here, we explain how the response of the cracked gas sensor for gas-insulated equipment 1 changes as the distance from the position of partial discharge, etc., was measured using the cracked gas generation simulation device shown in Fig. 5.

In this measurement, from electrode 41 in FIG. 5, point A was placed at 5 cm, point B at 20 cm, and point C at 40 cm. An irregular pitch is used to increase the number of measurement points around the discharge. According to FIG. 13, it can be seen that the decomposition gas generated near the electrode 41 diffuses as the distance from the electrode 41 increases, and the conductance to the decomposition gas decreases. Therefore, when the discharge occurs at the electrode 41, the decomposition gas sensor 1 for gas insulated equipment at point A reacts promptly, then the decomposition gas sensor 1 for gas insulation equipment at point B and finally C. At any point, the conductance increases in proportion to the duration of the discharge.

[0059] As described above, when a large number of the decomposition gas sensors 1 for gas insulation equipment of the insulation gas decomposition detection device are arranged, the one having the shortest distance reacts to the partial discharge. If the position is determined, abnormality diagnosis of high-voltage electrical equipment such as GIS can be performed quickly. In addition, when the conductance of the decomposition gas sensor 1 for gas-insulated equipment at two locations sequentially exceeds the reference value using diffusion, it can be determined that partial discharge has occurred somewhere between the two locations. In this case, it is also possible to reduce the number of decomposed gas sensors 1 for gas insulation equipment by utilizing the time difference.

Incidentally, the above-described decomposition gas sensor for gas-insulated equipment of Example 1 is produced by dielectrophoresis. Therefore, a carbon nanomaterial migration apparatus for producing the decomposition gas sensor 1 for a gas insulating device according to the first embodiment will be described. In FIG. 14, reference numeral 21 denotes a power supply unit for dielectrophoresis that applies an AC voltage to generate dielectrophoresis between the electrodes la and lb, and 22 can measure the impedance between the electrodes la and lb. The measurement unit 23 comprises a microprocessor or the like, reads and operates programs and data, controls the power supply unit 21 and the measurement unit 22 and performs calculations at the same time, 24 denotes a display unit, and 25 denotes a program And 25a is a data section that stores the amount of integration and time, and 26 is a clock section. The power supply section 21 must be an AC power supply for performing dielectrophoresis. The control configuration of the carbon nano material migration apparatus described above is basically the same as that of the gas measurement apparatus 6, and in the first embodiment, the gas measurement apparatus 6 is shared as the gas measurement / dielectrophoresis control apparatus 6a. I have.

Next, reference numeral 27 denotes an electrophoresis chamber for introducing a suspension solvent in which the carbon nanomaterial 2 is suspended in a solvent such as ethanol for electrophoresis. 28 is a container containing the suspended suspension solvent, 29 is a pump that sends the suspension solvent to the electrophoresis chamber 27, 30 is ultrasonic vibration provided to suspend the force nanomaterial 2 in the solvent And a stirring device 31 for supplying the container 28 to the container 28, and electromagnetic valves 31 and 32.

[0063] A process for producing the decomposition gas sensor 1 for gas insulation equipment using this carbon nanomaterial migration apparatus will be described. The electrodes la and lb of the thin-film electrode are formed on the insulating substrate 4, and the carbon nanomaterial 2 previously prepared in, for example, ethanol having a concentration of about 1 μg / ml in a container 28, for example, a diameter of 20 nm and a length of 5 nm— Pour 20nm multi-walled CNT (purity 95%). The arithmetic control unit 23 operates the stirrer 30 for about 60 minutes to disperse the carbon nanomaterial 2. In this state, the data section opens the solenoid valves 31 and 32 and operates the pump 29 to send the suspension into the electrophoresis chamber 27 having a volume of about 15 / il. Next, a high-frequency voltage is applied between the electrodes la and lb, and dielectrophoresis is started by the generated uneven electric field. At this timing, the timer 26 starts counting. The current is measured by the measuring unit 22 together with the time measurement by the timer unit 26. The arithmetic control unit 23 reads out a predetermined time corresponding to the planned accumulation amount of the decomposition gas sensor 1 for gas insulation equipment from the data unit 25a, stops the power supply unit 21 after counting out, stops the pump 29, and Close solenoid valves 31 and 32. Air is circulated in the electrophoresis chamber 27 at room temperature to evaporate ethanol in a relatively short time. After drying, the decomposition gas sensor for gas-insulated equipment 1 in which carbon nanomaterials 2 are integrated and cross-linked Take out. By controlling the time of dielectrophoresis in this way, the amount of accumulation of the carbon nanomaterial 2 can be controlled, and the highly sensitive decomposition gas sensor 1 for gas insulating equipment can be easily manufactured.

By the way, the dielectrophoretic force F is represented by a complex number represented by F = 2πε * a ³ ′ Re [K] VE ²

DEP DEP m

it can. Where, ε: dielectric constant of the suspension, a: half of the carbon nanomaterial when approximated by a sphere

m

Diameter, Re [K]: a parameter that depends on the complex permittivity of the minute object and suspension, E: electric field strength. This Re [K] changes to positive or negative as the frequency i¾r parameter of the electric field used for dielectrophoresis. Positive dielectrophoretic force works in a specific frequency range, for example, 10 kHz and 1 MHz, and negative dielectrophoretic force works in other cases. Therefore, it is necessary to select the frequency and apply the maximum positive dielectrophoretic force F to accumulate the carbon nanomaterial 2.

DEP

[0065] The carbon nanomaterial 2 has a force that can approximate a sphere such as fullerene. The force is generally a nano-sized and long fibrous material. However, according to the experiments, all can be operated in the same manner, and the carbon nanomaterial migration apparatus can move the polarized object to the region where the electric field is maximized by using the positive dielectrophoretic force. The frequency may be determined experimentally. In Example 1, dielectrophoresis was performed at a frequency of 100 kHz and a voltage amplitude of 5 V. In addition, such a frequency and a voltage amplitude are set for each carbon nanomaterial 2, and the relationship between the dielectrophoresis time and the accumulation amount is stored in the data section 25a.

As described above, the decomposed gas sensor 1 for gas-insulated equipment of Example 1 easily integrates the carbon nanomaterial 2 on the microelectrode using electrophoresis, which is an electrodynamic phenomenon, so that the electrode la, lb Thus, the crosslinked gas sensor 1 for gas-insulated equipment can be easily manufactured at low cost. The decomposition gas sensor 1 for gas-insulated equipment of Example 1 can detect a gas of 10 ppb or less at a high speed and a high accuracy at a normal temperature.

[0067] Then, the decomposed gas sensor 1 for gas-insulated equipment can detect a decomposed gas that does not normally exist in a GIS or the like as soon as it is generated, and can detect an abnormality in the GIS or the like in advance. is there. Conventional gas sensors using solid electrolytes must be used by heating to about 400 ° C with a heater that has poor detection sensitivity at room temperature, and the response is very slow. The gas decomposition equipment sensor 1 for gas-insulated equipment can be used at room temperature, is highly sensitive, has a very fast response, is easy to manufacture, is inexpensive, and is small and can easily obtain an electrical output. It can be used repeatedly.

[0068] Further, the insulating gas decomposition detection device of the present invention can immediately specify the position where the insulating gas is decomposed when the insulating gas is decomposed in the high-voltage electrical equipment.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. is there.

This application is based on a Japanese patent application filed on January 29, 2004 (Japanese Patent Application No. 2004-021531), the contents of which are incorporated herein by reference.

Industrial applicability

The present invention can be applied to a gas sensor that is inexpensive, responds at high speed, has high detection accuracy, and is easy to manufacture, and is particularly applicable to a decomposition gas sensor for gas insulated equipment that detects an abnormality in a substation facility in advance. It can be applied to an insulation gas decomposition detection device that can use it to diagnose abnormalities in high voltage electrical equipment such as GIS.

Claims

The scope of the claims

[1] A decomposed gas sensor for a gas insulating device capable of detecting a decomposed gas of an insulating gas sealed in a high-voltage electric device, comprising a detection unit that also has a semiconductor carbon nanomaterial power, wherein the decomposed gas is the semiconductor A decomposed gas sensor for a gas insulation device, which outputs a change in impedance of the detection unit by adsorbing and reacting with a carbon nanomaterial.

[2] The decomposition gas sensor according to claim 1, wherein the insulation gas is (1) SF.

6 Gas, (2) Nitrogen gas, (3) One of the forces of air or a mixture of two or more with the one as the main component, or (1) (2) 2. The decomposed gas sensor for gas-insulated equipment according to claim 1, wherein the detection section detects a decomposed gas of the gas including an insulating gas other than (3).

3. The method according to claim 1, wherein a change in conductance is output as the change in impedance.

3. The decomposition gas sensor for gas-insulated equipment according to 1 or 2.

[4] A capacitance change is output as the impedance change.

[5] The gas-insulated equipment according to any one of [14] to [14], further comprising a pair of electrodes, wherein the detection unit is made of a semiconductor carbon nano material bridged between the electrodes. Decomposition gas sensor.

6. The gas insulating device according to claim 5, wherein the electrode has an electric field concentration edge for generating an uneven electric field when an AC voltage is applied, and the detection unit is formed by dielectrophoresis. For decomposition gas sensor.

7. The electrode according to claim 6, wherein the electrode is a thin film electrode provided on an insulating substrate, and the electric field concentration edge is an edge of a protrusion formed on each of the electrodes. Decomposition gas sensor for gas insulation equipment.

[8] The decomposition gas sensor for gas-insulated equipment according to any one of claims 117, wherein the semiconductor carbon nanomaterial is a semiconductor.

[9] The decomposed gas sensor for gas-insulated equipment according to any one of claims 117, wherein the semiconductor carbon nanomaterial is an n-type semiconductor.

[10] The gas-insulated equipment decomposition gas sensor according to any one of [11] to [9], wherein a plurality of the gas-insulation equipment decomposition gas sensors are arranged in an insulating gas of the high-voltage electric equipment, and a power supply for applying a voltage to the gas insulation equipment decomposition gas sensor. A measuring unit that detects a change in impedance of each of the decomposition gas sensors for gas-insulated equipment when the voltage is applied, and a control unit that compares the impedance change detected by the measuring unit with a predetermined reference value. And a controller configured to determine a position of the cracked gas sensor for a gas insulating device that has output an impedance change equal to or greater than a reference value as a position where the cracked gas is generated.

[11] A decomposed gas sensor for a gas insulated device provided with a detection unit made of a semiconductor carbon nano material in an insulating gas of a high-voltage electric device, and a decomposed gas generated from the insulating gas is provided in the decomposed gas sensor for a gas insulated device. And reacting the gas with the semiconductor carbon nanomaterial, and detecting the decomposed gas by the impedance change of the detection section.