| Title of Invention | "A DISSOLVED GAS ANALYZER OF INSULATING OIL" |
|---|---|
| Abstract | A dissolved gas analyzer of insulating oil comprising: a gas extractor 3 to draw insulating oil 2 from an oil- filled equipment 1, a gas detector 15 having a plurality of semiconductor sensors sl-S7 for detecting concentration of a component gas from a plurality of component gases included in the insulating oil 2 drawn into the gas extractor 3; a sample gas supply system for sampling the plurality of component gases in the insulating oil 2 drawn into the gas extractor 3 and supplying to the gas detector 15 as the sample gas for measuring; a reference gas supply system for supplying a reference gas to be a reference for the detection values of the semiconductor sensors sl-s7 to the gas detector 15; a switch means 10 for switching between the sample gas supply system and the reference gas supply system and supplying the component gases or the reference gas to the gas detector 15; and a calculation device 201-205 for calculating the concentration of the plurality of component gases dissolved in the insulating oil 2 based on the detection values measured by the plurality of semiconductor sensors sl-s7 in the gas detector 15 for the sample gas and the reference gas. |
| Full Text | - 1 - TITLE OF THE INVENTION DISSOLVED GAS ANALYZER OF INSULATING OIL AND METHOD FOR ANALYZING DISSOLVED GAS ANALYZER OF INSULATING OIL BACKGROUND OF THE INVENTION [Field of the Invention] The present invention relates to a dissolved gas analyzer of insulating oil such as an insulating oil-filled transformer and a method for analyzing dissolved gas analyzer of insulating oil. [Prior Art] One of the prior art of the dissolved gas analyzer of insulating oil relating to insulating oil in the transformer which is oil-filled or oil-sealed equipment is disclosed in the Japanese Patent Application Laid-Open Publication No. Sho 59 (1984)-160745. In this prior art, a gas permeable material is used to separate the gas in the insulating oil, and the separated gas is detected by a plurality of semiconductor sensors which react with various types of gases. A plurality of calculation formulas which show the relationship between gas concentration and reactivity as a simultaneous algebraic equation is used to solv the gas concentration, thereby the concentration of hydrogen, carbon monoxide, carbon dioxide, methane, ethane, ethylene, and acetylene are obtained. - 2 - Another prior art relating to a dissolved gas analyzer is disclosed in the Japanese Patent Application Laid-Open Publication No. Hei 5 (1990)-52787. In this prior art, gases dissolved in the oil are extracted by various extraction methods and hydrogen or acetylene in the gases is detected respectively by using a semiconductor sensor such a sensor which reacts only with hydrogen or acetylene without the step of separation into single gas. Similarly, an other prior art relating to a dissolved gas analyzer is disclosed in the Japanese Patent Application Laid-Open Publication No. Hei 6 (1991)-160329. In this prior art, gases dissolved in the oil are extracted by various extraction methods and hydrogen, carbon monoxide or combustible gases is detected respectively by using semiconductor sensors such as sensors which reacts only with hydrogen, carbon monoxide, or total combustible gases such as hydrogen, carbon monoxide, methane, ethane, ethylene or acetylene without the step of separation into single gas. In addition, if abnormalities such discharging or overheating occurs inside the oil-immersed transformer, insulating oil is resolved and gas is generated in the oil. The amount of gas generated in the oil and the pattern of gas generation varies depending on the type of abnormality occurring inside the transformer. As a result, by referring - 3 - to past examples and adjusting the amount of gas generated and the pattern of gas generation, it is possible to determine abnormal types or levels. Thus, in the past, one method of deterioration or abnormality detection in the oil-immersed transformer has been analysis of the gases dissolved in the insulating oil (simply called dissolved gas analysis hereinafter). Patent Document 1: Japanese Patent Application Laid- Open Publication No. Sho 59 (1984)-160745 Patent Document 2: Japanese Patent Laid-Open No. Hei 5 (1990)-52787 [Patent Document 3] Japanese Patent Application Laid- Open Publication No. Hei 6 (1991)-160329 Patent Document 4: Japanese Patent Laid-Open No. Hei 5 (1990)-346414 SUMMARY OF THE INVENTION A semiconductor sensor formed from metallic oxides such as tin oxide, tungsten oxide, and zirconium oxide which is a general use semiconductor which detects gas using a dissolved gas analyzer based on various gas detection methods reacts with various gases, but on the other hand, there is a problem in that the concentration of a particular gas cannot be accurately detected. Furthermore, another property of the semiconductor sensor is that the - 4 - sensor output is not fixed even for a fixed concentration of a particular gas and this is problematic in that the sensor output changes. This is caused by the effect of water particles or contaminants which adhere to the surface of the semiconductor sensor. In the method for detecting gas described in Patent Document 1 and Patent Document 4, only the gas in the insulating oil is measured using the semiconductor sensor, but even in that case, the output is not fixed and there is a problem in that measurement repeatability cannot be obtained. In the gas detection method of Patent Document 2 and Patent Document 3 also, gas concentration is obtained using a semiconductor which has gas sensitivity, but the sensor output is not fixed and measurement repeatability is not obtained. In addition, in the gas detection method of Patent Document 2 and Patent Document 3, gas concentration is obtained by using a semiconductor sensor which has gas selectivity, but the semiconductor sensors that have gas sensitivity can only detect hydrogen, carbon monoxide and acetylene and cannot detect the gas component concentrations for methane, ethane and ethylene. The object of the present invention is to provide a dissolved gas analyzer of insulating oil and a method for - 5 - analyzing dissolved gas analyzer of insulating oil to detect the concentration of various gases with high detection repeatability using a general-use semiconductor. The dissolved gas analyzer of insulating oil in the present invention comprising: a gas extractor to draw insulating oil from an oil-filled equipment, a gas detector having a plurality of semiconductor sensors for detecting concentration of a component gas from a plurality of component gases included in the insulating oil drawn into the gas extractor; a sample gas supply system for sampling the plurality of component gases in the insulating oil drawn into the gas extractor and supplying to the gas detector as the sample gas for measuring; a reference gas supply system for supplying a reference gas to be a reference for the detection values of the semiconductor sensors to the gas detector; a switch means for switching between the sample gas supply system and the reference gas supply system and supplying the component gases or the reference gas to the gas detector; and a calculation device for calculating the concentration of the plurality of component gases dissolved in the insulating oil based on the detection values measured using the plurality of semiconductors in the gas detector for the sample gas and the reference gas. In addition, the method of analyzing dissolved gas of - 6 - insulating oil comprising the steps of: drawing insulating oil stored in an oil-filled equipment and supplying the insulating oil to a gas extractor; sampling a plurality of component gases included in the insulating oil drawn in the gas extractor and then allowing supply to a gas detector via a sample gas supply system as a sample gas to be measured; allowing a reference gas to be the detection value of the plurality of semiconductor sensors provided in a gas detector to be supplied to the gas detector via the reference gas supply system; switching between the sample gas to be supplied via the sample gas supply system and the reference gas to be supplied via the reference gas supply system and supplying to the gas detector; detecting the concentration of component gas from the plurality of components gas Included in the sample gas and the concentration of the reference gas by the plurality of semiconductors provided in the gas detector; and calculating the concentration of the plurality of component gases included in sample gas based on each of the detection values measured by the plurality of semiconductor sensors in the gas detector for the sample gas and the reference gas. According to the present invention, a dissolved gas analyzer of insulating oil and a method for analyzing dissolved gas analyzer of insulating oil enable to detect - 7 - the concentration of various gases with high detection repeatability using a general-use semiconductor is realized. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a general schematic view to show a dissolved gas analyzer of insulating oil according to an embodiment of the present invention. Fig. 2 is a flow chart to show the dissolved gas analysis steps in the dissolved gas analyzer of insulating oil shown in Fig. 1. Fig. 3 is a general schematic view to show opened and closed states of the four-way valve at the time of dissolved gas extraction in the dissolved gas analyzer of insulating oil according to the embodiment of the present invention shown in Fig. 1. Fig. 4 is a general schematic view to show opened and closed states of the four-way valve at the time sample gas measurement in the dissolved gas analyzer of insulating oil according to the embodiment of the present invention shown in Fig. 1. Fig. 5 is a characteristic chart to show the output of the semiconductor sensors of the gas detector for detecting the gas concentrations of the various gases dissolved in the insulating oil in the dissolved gas analyzer of insulating oil according to the embodiment of the present - 8 - invention shown in Fig. 1. Fig. 6 is a block diagram for calculating the gas concentration of the various dissolved gases dissolved in the insulating oil in the dissolved gas analyzer of insulating oil according to the embodiment of the present invention shown in Fig. 1. Fig. 7 is a general schematic view to show a portable dissolved gas analyzer of insulating oil according to another embodiment of the present invention. Fig. 8 is a flow chart to show the dissolved gas analysis steps in the dissolved gas analyzer of insulating oil shown in Fig. 7. Fig. 9 is a general schematic view to show opened and closed states of the four-way valve at the time of dissolved gas extraction in the dissolved gas analyzer of insulating oil according to the another embodiment of the present invention shown in Fig. 7. Fig. 10 is a general schematic view to show opened and closed states of the four-way valve at the time sample gas measurement in the dissolved gas analyzer of insulating oil according to the embodiment of the present invention shown in Fig. 7. Fig. 11 is a block diagram for calculating the gas concentration of the various dissolved gases dissolved in the insulating oil in the dissolved gas analyzer of - 9 - insulating oil according to the another embodiment of the present invention shown in Fig. 7. Fig. 12 is a general schematic view to show a monitoring device of the transformer including a dissolved gas analyzer of insulating oil as an embodiment of the present invention. FIG. 13 is a sectional view to show a structure of a gas extractor in a dissolved gas analyzer of insulating oil according to one of other embodiment of the present invention. FIG. 14 is a plain view to show a grooved flange of a gas extractor in a dissolved gas analyzer of insulating oil according to the one of other embodiment of the present invention shown in Fig. 13. FIG. 15 is a plain view to show a grooved flange of a gas extractor with an arc-shaped gas reservoir in a dissolved gas analyzer of insulating oil according to the one of other embodiment of the present invention shown in Fig. 13. FIG. 16 is a plain view to show a grooved flange of a gas extractor with a zigzag shape gas reservoir in a dissolved gas analyzer of insulating oil according to the one of other embodiment of the present invention shown in Fig. 13. FIG. 17 is a plain view to show a grooved flange of a - 10 - gas extractor with a spiral shape gas reservoir in a dissolved gas analyzer of insulating oil according to the one of other embodiment of the present invention shown in Fig. 13. DETAILED DESCRIPTION OF THE INVENTION Next, a dissolved gas analyzer of insulating oil which is an embodiment of the present invention is explained by referring drawings. [Embodiment 1 of the invention] Fig. 1 shows the structure of the dissolved gas analyzer 20 of insulating oil installed in the insulating oil immersed transformer as the first embodiment of the present invention and this is the type of dissolved gas analyzer of insulating oil that is attached to the transformer, inside of which is filled or sealed with insulating oil. The dissolved gas analyzer of insulating oil is installed in the oil immersed transformer of this embodiment of the present invention performs dissolved gas analysis in the insulating oil for hydrogen, carbon monoxide, acetylene, ethylene, methane and ethane. In Fig. 1, the inside of the oil immersed transformer 1 is filled with insulating oil 2. The dissolved gas analyzer 20 is provided with the gas extractor 3 which causes insulating oil to flow into and out of the oil immersed - 11 - transformer 1 connected to the oil immersed transformer 1 via the pipe 25A and the pipe 25B, and the gas generated in the insulating oil 2 filled or sealed in the oil immersed transformer 1 is extracted by using the bubbling method in the gas extractor 3. The main body of the gas extractor 3 has an open and close valve 4. The pipe 25A and 25B have an oil feed pump 5A and 5B respectively and the oil feed pump 5A supplies a prescribed amount of the insulating oil from the oil immersed transformer 1 to the gas extractor 3. In addition, the oil feed pump 5B returns the insulating oil 2 from the gas extractor 3 to the oil immersed transformer 1 after the gas has been extracted. There is a nitrogen pump 6 which supplies nitrogen and the nitrogen is led from the nitrogen pump 6 to the four- way switching valve 10 which is described hereinafter via the nitrogen supply pipe 18A. There is also an oxygen pump 7 which supplies oxygen and the oxygen is led from the oxygen pump 7 to the gas regulator 13 which is described hereinafter, via the oxygen supply pipe 18B. The oxygen supply pipe 18A and the nitrogen supply pipe 18B have the regulators 8A and 8B respectively, and the pressure of the nitrogen and oxygen supplied from the oxygen pump 6 and the nitrogen pump 7 to the four-way switching valve 10 and the gas regulator 13 can be - 12 - regulated. Similarly, the oxygen supply pipe 18A and the nitrogen supply pipe 18B have flow meters 9A and 9B respectively and the flow rate of nitrogen and oxygen supplied from the nitrogen pump 6 and the oxygen pump 7 to the four-way switching valve 10 and the gas regulator 13 respectively can be measured. The four-way switching valve 10 is connected to the nitrogen supply pipe 18A for supplying nitrogen from the nitrogen pump 6 and the gas extraction pipe 18C1 which leads the nitrogen supplied via the nitrogen supply pipe 18A to the gas extractor 3. By switching the four-way switching valve 10, the nitrogen gas forms a path for supplying nitrogen gas from the nitrogen pump 6 to the gas extractor 3 via the air supply pipe 18A and the gas extraction pipe 18C1. The four-way switching valve 10 connects the gas extraction valve 18C2 which leads the gas mixture of dissolved gas generated in the insulating oil 2 which is included inside the oil immersed transformer 1 and dissolved gas mixture supply pipe 18D which leads the gas mixture of dissolved gases led via the gas extraction pipe 18C2 to the gas regulator 13. By switching the four-way switching valve 10, a flow path is formed which supplies gas mixture of dissolved - 13 - gases from the gas extractor 3 to the gas detector 15 described hereinafter via the gas extraction pipe 18C2 and the dissolved gas mixture supply pipe 18D. The gas extraction pipe 18C1 has an air pump 11, and when this air pump 11 is operated, bubbling occurs. In addition, the gas extractor 3 has a filter 12 and when the gas mixture of dissolved gases generated in the insulating oil included inside the oil immersed transformer 1 that is led to the gas extractor 3 is led out to the four-way switching valve 10 from the gas extractor 3 via the gas extraction pipe 18C2, the insulating oil that is mixed into the gas mixture of dissolved gases in an atomized state is removed. The gas mixture of dissolved gases generated in the insulating oil included inside the oil immersed transformer 1 that is led to the gas extractor 3 is supplied to the gas detector 15 via the gas extraction pipe 18C2, the dissolved gas mixture supply pipe 18D and the sample gas supply pipe 18E. The connection portion of the dissolved gas mixture supply pipe 18D and the sample gas supply pipe 18E has a gas regulator 13 and the oxygen supply pipe 18B which supplies oxygen from the oxygen pump 7 is connected to the gas regulator 13. In addition, oxygen is mixed with the gas mixture of - 14 - dissolved gases supplied to the gas detector 15 in a prescribed proportion using the gas regulator 13. The sample gas generated at the gas regulator 13 is supplied to the thermostat 14 via the sample gas supply pipe 18E, and the temperature of the sample gas which is a gas mixture in which nitrogen, oxygen and dissolved gas are mixed in the gas regulator 13 is regulated to a prescribed temperature by the thermostat 14. The gas detector 15 has semiconductor sensors formed from metal oxides such as tin oxide, tungsten oxide, zirconium oxide and the gas mixture of nitrogen and oxygen and the gas mixture of nitrogen, oxygen and gas dissolved in the insulating oil respectively which are the reference gases, are measured using the semiconductor sensor and these measured values are output to the computer 16 as output signals. At the computer 16, the concentration of the gas component of the gas dissolved in the insulating oil is calculated by computations based on the output signal from the semiconductor sensor in the gas detection section 15 and the calculated concentration of the gas composition of the gas in the dissolved in the insulating oil is displayed on a monitor or the like. In addition the computer 16 sends commands to the elements comprising the dissolved gas analyzer disposed in - 15 - the insulating oil immersed transformer in the embodiment of this invention which include the ON and OFF for the pumps and the switching operations and open and close operations for the switch valve and the exhaust valves. The gas composition of the sample gas in which nitrogen, oxygen and gas dissolved in the insulating oil that was detected by the semiconductor sensor disposed in the gas detector 15 are sent to the outside via the exhaust pipe 18G after the concentration of each of the gas components is detected, but the exhaust pipe 18G has a check valve 17 which prevents the air from outside from flowing into the gas detector 15. Of the aforementioned pipes, the gas extraction pipe 18C1 is a pipe which runs from the four-way switching valve 10 via the air pump 11 that is installed in the gas extraction pipe 18C1, the gas extractor 3, the filter 12 installed in the gas extractor 3 and the gas extraction pipe 18C2 and returns once again to the four-way switching valve 10. Also, the dissolved gas mixture supply pipe 18D is a pipe which leads the gas mixture of nitrogen and gas dissolved in the insulating oil to the thermostat 14 and the gas detector 15. The sample gas supply pipe 18E is a pipe which leads the gas mixture of gas dissolved in the insulating oil, nitrogen and oxygen that is generated at - 16 - the gas regulator 13 to the thermostat 14 and the gas detector 15. Next, the steps of the dissolved gas analyzer for the dissolved gas analyzer of insulating oil installed in the oil immersed transformer which is shown in Fig. 1 as the embodiment of the present invention are shown in Fig. 2. In Fig. 2, in the measuring operation, first the measurement preparation step 101 is performed. Next, dissolved gas extraction step 102 is performed. Dissolved gas extraction step 102 is performed in parallel with the nitrogen and oxygen gas mixture measurement step 103. Finally, sample gas measurement step 104 is performed. The gas concentration calculation step 105 in which the concentration of each component gas is measured based on the measurement results from the step 103 of measuring the nitrogen and oxygen gas mixture and the step 104 of measuring the sample gas is performed. Each of the steps in the measurement operation is repeated. To explain more specifically, in the step 101 of measurement preparation, the four-way switching valve 10 is operated as shown in Fig. 1 and nitrogen from the nitrogen pump 6 is supplied to the four-way switching valve 10 via the nitrogen supply pipe 18A. The supplied nitrogen flows from the nitrogen supply pipe 18A via the four-way switching valve 10 and into the gas extractor 3 from the - 17 - gas extraction pipe 18C. Subsequently, nitrogen passes through the gas extractor 3 and flows downstream to the gas extraction pipe 18C2 and the dissolved gas mixture supply pipe 18D, and the inside of the devices and the flow paths which reach the dissolved gas mixture supply pipe 18D from the nitrogen supply pipe 18A are displaced with nitrogen. In addition, oxygen is supplied to the gas regulator 13 from the oxygen pump 7 via the oxygen supply pipe 18B, and the supplied oxygen is mixed with nitrogen gas in the gas regulator 13 and forms the gas mixture of nitrogen and oxygen which will become the reference gas. Subsequently, the gas mixture of nitrogen and oxygen which is the reference gas generated at the gas regulator 13 flows down to the thermostat 14 and the gas detector 15 via the sample gas supply pipe 18E and the inside of the devices and the flow paths are replaced with the gas mixture of nitrogen and oxygen which is the reference gas. Next, in step 102 of dissolved gas extraction, as shown in Fig. 3, the four-way switching valve 10 is operated and switching is done. In addition, by switching the four-way switching valve 10, the flow path A which forms a closed system of the gas extraction pipe 18C1, the gas extraction pipe 18C2, and the gas extractor 3, as well as the flow path B which supplies nitrogen from the nitrogen pump 6 to - 18 - the gas regulator 13 via the nitrogen supply pipe 18A and the four-way switching valve 10. In addition, by supplying oxygen from the oxygen pump 7 to the gas regulator 13 via the oxygen supply pipe 18B, the gas mixture of nitrogen and oxygen which is the reference gas in which oxygen, is mixed with the nitrogen that flows down the flow path B in the gas regulator 13. This gas mixture of nitrogen and oxygen which is the reference gas is supplied to the thermostat 14 and the gas detector 15 via the sample gas supply pipe 18E. The gas extraction operation is performed in the flow path A. That is to say, the gas extraction operation in the flow path A is one in which first, the release valve 4 provided in the gas extractor 3 is put in the release state and the oil feed pump 5A in the pipe 25A is actuated and the insulating oil 2 included inside the oil immersed transformer 1 is supplied to the gas extractor 3. Next, after the pouring of the insulating oil 2 into the gas extractor 3 is complete, the release valve closes simultaneously and the air pump 11 which is in the gas extraction pipe 18C1 which forms the flow path A is activated and the nitrogen inside the flow path A is circulated and sampling of the dissolved gas that is dissolved in the insulating oil 2 that is poured into the gas extractor 3 due to bubbling is performed. - 19 - Bubbling refers to a sampling method for sample gas in which, in a sealed system, an inert gas such as nitrogen and the like is blown into a liquid in which a gas for sampling is dissolved and after the gas dissolved in the liquid and the gas above the liquid surface are brought to equilibrium, the gas above the liquid surface is sampled. Nitrogen is used as the inert gas for performing bubbling because it prevents oxygen from mixing in the insulating oil. The insulating oil after dissolved gas is sampled from the insulating oil 2 that is included in the transformer 1 is returned to the transformer 1 from the gas extractor 3 and then re-used, but in the case where oxygen is mixed in the insulating oil 2, there is the concern that the insulating oil 2 and the insulating paper will deteriorate due to oxygen. For this reason, oxygen or inert gases such as helium, argon and the like are used for bubbling. At the time of bubbling, the relationship between the bubbling time and the gas concentration in nitrogen of the inert gas which circulates inside the sealed system is examined before hand so that an appropriate time is selected. The relationship between the concentration of the dissolved gas in insulating oil and the concentration of gas extracted as the sample gas by bubbling is different - 20 - depending on the gas composition. As a result, the correlation between the amount of dissolved gas in the insulating oil and the amount of gas extracted by bubbling can be obtained in advance. Next, step 103 of measuring the gas mixture of nitrogen and oxygen which is the reference gas, measurement of the gas mixture of nitrogen and oxygen which is the reference gas is performed in the gas detector 15 via the flow path B which is formed by the switching operation of the four-way switching valve 10. That is to say, nitrogen from the nitrogen pump 6 is supplied to the gas regulator 13 via the nitrogen supply pipe 18A and the four-way switching valve 10, and oxygen from the oxygen pump 7 is supplied to the gas regulator 13 via the nitrogen supply pipe 18B and the gas mixture of nitrogen and oxygen (oxygen 20%, nitrogen 80%) which is the reference gas in which the composition proportions of both are adjusted at the gas regulator 13 is supplied to the gas detector 15 via the sample gas supply pipe 18E and the thermostat 14. When the detected output of the reference gas that is detected at the semiconductor sensors SI- S7 disposed in the gas detector section 15 becomes stable, the detected output is input into the computer 16 as the sensor output for the gas mixture of nitrogen and oxygen which is the - 21 - reference gas. Next, in step 104 of measuring sample gas, as shown in Fig. 4, the four-way switching valve 10 is switched and nitrogen from the nitrogen pump 6 is supplied to the gas extractor 3 via the nitrogen supply pipe 18A, the four-way switching valve 10 and the gas extraction pipe 18C1, and the supplied nitrogen flows down to the gas regulator 13 from the gas extractor 3 via the gas extraction pipe 18C2 and the dissolved gas mixture supply pipe 18D. According to this operation, the gas mixture of nitrogen and oxygen which was sampled from the flow path A is pushed out by the nitrogen supplied from the nitrogen pump 6 and led to the gas regulator 13. The oxygen supplied from the oxygen pump 7 via the oxygen supply pipe 18B is added to the gas mixture of dissolved gas led to the gas regulator 13 at the gas regulator 13 and the sample gas is generated. In addition, the sample gas generated at the gas regulator 13 is supplied to the gas detector 15 and the concentration of the components of the sample gas is detected. Here, the sample gas is formed by adding oxygen to the gas mixture of dissolved gases in the regulator 13 because oxygen is necessary for measurement of the sample gas using the semiponductor sensors S1 - S7 provided in the gas detector 15. - 22 - By switching the gas supplied to the semiconductor sensors S1 - S7 provided in the gas detector 15 from the gas mixture of nitrogen and oxygen which is the reference gas to the sample gas, there is a great change in the sensor output of the sample gas detected at the semiconductor sensor S1 - S7 around the time of switching of the supplied gas. When the sensor output is substantially fixed to be stable after the change in the sensor output, the sensor outputs are input into the computer 16 as the sensor outputs of the semiconductor sensors S1 - S7 for the sample gas. After the sample gas is measured by the semiconductor sensors S1 - S7 of the gas detector 15, nitrogen from the nitrogen pump 6 is supplied to the gas extractor 3 while actuating the oil feed pump 5B provided in the pipe 25B and the insulating oil 2 supplied to the gas extractor 3 is returned to the oil immersed transformer 1. The series of operations is performed automatically upon receiving commands from the computer 16. Fig. 5 is a pattern diagram showing the sensor output of the gas detected at the semiconductor sensors S1 - S7 of the gas detector 15 and the horizontal axis shows time t while the vertical axis shows the electrical resistance R of the sensor output detected at the semiconductor sensors S1 - S7, and the sensor output is shown by the curve in the - 23 - drawing. In Fig. 5, the measurement time from time t = to to t = tl shows the sensor output when the gas mixture of oxygen and nitrogen (oxygen 20%, nitrogen 80%) which is the reference gas. In addition, the measurement time from time t = tl to t = t2 shows the sensor output when the sample gas is measured and the measurement time from time t = t2 to t = t3 shows the sensor output when the gas mixture of oxygen and nitrogen which is the reference gas is measured a second time. First, at the measurement time t = to to t = tl, the electrical resistance R which is the sensor output of the reference gas at the time t = tl shows R0. The sensor output from time t = 0 to t = tl changes mildly because the sensor output is drifting. The measurement time from time t = tl to t = t2 shows the sensor output when the sample gas supplied by switching from the reference gas by the operation of the four-way switching valve 10 is measured. By starting supply of the sample gas at time t = tl and doing measurement, the sensor output is suddenly reduced and then immediately, the changes in the sensor output become mild and the sensor output becomes stable at time t = t2. The electrical resistance R which is the sensor output - 24 - of the sample gas at the time t = t2 shows Rl. The measurement time from time t = t2 to t = t3 shows the sensor output when there is a switch once again from supply of the sample gas to the reference gas by the switching operation of the four-way switching valve 10 and the gas mixture of nitrogen and oxygen which is the reference gas is measured. By starting supply of the gas mixture of nitrogen and oxygen which is the reference gas at time t = t2 and doing measurement, the sensor output is suddenly increased and then the changes in the sensor output become mild and the sensor output becomes stable at time t = t3. The electrical resistance R which is the sensor output of the reference gas at the time t = t3 shows R2. The sensor output from the time t = 3 to the t = 4 does not change much and is in a stable state. In this case, the electrical resistance R0 of the sensor output is detected in advance for the gas mixture of nitrogen and oxygen which is the reference gas using the semiconductor sensors and registered at the computer 16. In addition, the sample gas will be the gas component for analysis, and the electric resistance Rl which is RCO1 of the sensor output using the semiconductor sensors in the case of a specific concentration such a gas concentration of 10 ppm for carbon monoxide gas is detected in advance - 25 - and registered at the computer 16. Similarly, the value for the electric resistance R of the sensor output using the semiconductor sensors in the case of a specific concentration can be detected in advance and registered at the computer 16 for hydrogen, acetylene, ethylene, methane and ethane respectively which are other gases for detection. In addition, as described above, by measuring the reference gas and the sample gas using the semiconductor sensors SI - S7 provided in the gas detector 15, the electrical resistance RO of the sensor output for the reference gas and the electrical resistance Rl of the sensor output for a gas in the sample gas that is to be measured, such as carbon monoxide for example, are measured and the sensor output proportion R0/R1 for the carbon monoxide gas is calculated. The sensor output ratio R0/RCO1 is calculated based on the electrical resistance RCO1 of the carbon monoxide gas of a gas concentration of 10 ppm which is detected in advance at the computer 16, and if the ratio R0/R1 of the sensor outputs are compared, the gas concentration of the carbon monoxide in the sample gas can be accurately calculated. By measuring the reference gas and the sample gas using the semiconductor sensors SI - S7 provided in the gas detector 16, if the ratio R0/R1 for the sensor output for - 26 - hydrogen, acetylene, ethylene, methane and ethane which are other gases for detection are calculated and compared, the gas concentration of specific components in the sample gas can be correctly calculated. In order to prevent measurement error due to drifting, the measurement value for the gas mixture of nitrogen and oxygen which is the reference gas uses RO which is the sensor output for the reference gas at time t = tl immediately before switching to the sample gas and R2 which is the sensor output for the reference gas at time t = t3 at which the output is stable after switching to the gas mixture of nitrogen and oxygen which is the reference gas once again. If the measurement value for the sample gas uses Rl which is the sensor output of sample gas at the time t = t2 immediately before switching to the gas mixture of nitrogen and oxygen, measurement error due to drifting is prevented. In this case, the ratio R2/R1 rather than the ratio R0/R1 for the sensor output is to be calculated. In addition, assuming that after the time t = tl, measurement of the gas mixture of nitrogen and oxygen which is the reference gas, the sensor output RO' for the gas mixture of nitrogen and oxygen at time t = t2 is estimated and the output corresponding to the concentration of the gas for detection in the sample gas may be calculated as - 27 - the sensor output RO'/Rl. Fig. 6 shows a block diagram for calculating the gas concentration of the various dissolved gases dissolved in the sample gas detected by the semiconductor sensors S1 - S7 disposed in the gas detector 15 in the dissolved gas analyzer of insulating oil in the first embodiment of the present invention shown in Fig. 1 to Fig. 5 and the sensor output for the sample gas are input into the computer 16 and the gas concentration of each gas in the sample gas to be detected are calculated. As described above, the electrical resistance R which is the sensor output from the semiconductor sensors S1 - S7 for each gas to be detected at a specific concentration is obtained in advance to correspond with the reference gas and each gas to be detected. In Fig. 6, the concentration of the gas components to be measured that are included in the sample gas are calculated by the calculators 201 to 205 that are installed in the computer 16 based on the output detected by the plurality of semiconductor sensors SI - S7 which have different properties for the gas mixture of nitrogen and oxygen which is the reference gas and the sample gas. The semiconductor sensor used is preferably which reacts with few types of gases. In the step for calculating the gas concentration of - 28 - each type of gas included in the sample gas to be measured, first the gas concentration of gas components for which the concentration can be obtained using the output detected at a small number of semiconductor sensors from among the semiconductor sensors S1 - S7. Next, by substituting the concentration of the gas components that were obtained first into a calculation formula that shows the relationship between the reaction properties and gas concentration, an unknown gas concentration is calculated using the output detected using the remaining semiconductor sensors. This calculation is repeated to obtain the other unknown gas concentrations and the number of unknown gas concentrations is gradually decreased until the concentration of all the gas components are finally obtained. In this embodiment of the present invention, the concentrations are calculated in the order of hydrogen, carbon monoxide, acetylene, ethylene, methane and then ethane. Of the semiconductor sensors S1 - S7, by first obtaining the gas concentration of gas components for which the concentration can be obtained using a small number of semiconductor sensors from among the semiconductor sensors S1 - S7, the amount of calculations for the gas concentration computations can be reduced and the detection - 29 - accuracy for the gas to be detected is increased.. In addition, in the block diagram for calculating the gas concentration of the various dissolved gases shown in Fig. 6, the calculation values for the gas concentrations of hydrogen, carbon monoxide, acetylene, ethylene, methane and ethane for detection that are included in the sample gas and calculated using the calculators 201 to 205 are input in the monitoring device 210 and can be monitored at all times. In this case, if the permissible values for gas concentrations to be detected are input from the setting device 220 to the monitoring device 210, it becomes possible for a warning to be given at the monitoring device 210 for gas concentrations to be detected which exceed the permissible values. In addition, the gas concentrations to be detected and the warning displays from the monitoring device 210 can be displayed at the display device 230. Next, in this embodiment of the present invention, the gas concentration calculation method is described for the case where there is linearity between the concentrations of the gas for detection and the detection properties of the semiconductor sensors. In Fig. 6, the gas concentration calculations are described for the case where detection is done for the gas mixture of nitrogen and oxygen which is the reference gas - 30 - and for the sample gas. First, in the case where the hydrogen concentration NH2 is obtained from the sample gas, the calibration curve (ratio of electrical resistance for detection concentration and sensor output) for the output Gl detected by the sensor SI and the concentration NH2 of the hydrogen which is the gas to be detected, is shown by the functional equation (equation 1) which is registered at the calculator 201. Gl = 1 + A11-(NH2)B11 .................................. (Equation 1) Here All and Bll are constants obtained by measuring a gas mixture of hydrogen and air using the sensor S1. The hydrogen concentration NH2 is obtained by calculations by substituting output detected by the sensor S1 for Gl in Equation 1 of calculator 201. Next, in the case where the concentration of carbon monoxide NCO is obtained from the sample gas, the calibration curve for the output G2 detected by the sensor S2, the hydrogen concentration NH2, and the carbon monoxide concentration NCO is shown by Equation 2 which is the functional Equation registered in the calculator 202. G2=1+NH2/(NH2+NCO)A21(NH2)B21+NCO/(NH2+NCO)A22-(NCO)B22 ..............................................(Equation 2) Here A21, A22, B21 and B22 are constants obtained by measuring a gas mixture of hydrogen and air and a gas mixture of carbon monoxide and air using the sensor S2. - 31 - The carbon monoxide concentration NCO is obtained by calculations by substituting output detected by the sensor S2 for the hydrogen concentration NH2 first obtained in G2 in Equation 2 of calculator 202. Next, in the case where the acetylene concentration NC2H2 is obtained from the sample gas, the calibration curve for the output G3 detected by the sensor S3, the carbon monoxide concentration NCO and the acetylene concentration NC2H2 is shown by Equation 3 which is the functional equation registered in the calculator 203. G3=1+NCO/(NCO+NC2H2)-A31-(NCO)B31+NC2H2/(NCO+NC2H2)A32-(NC 2H2)B32............................................................. (Equation 3) Here A31, A32, B31 and B32 are constants obtained by measuring a gas mixture of carbon monoxide and air and a gas mixture of acetylene and air using the sensor S3. The acetylene concentration NC2H2 is obtained by calculations by substituting output detected by the sensor S3 for the carbon monoxide concentration first obtained in G3 in Equation 3 of calculator 203. Next, in the case where the ethylene concentration NC2H4 is obtained from the sample gas, the calibration curve for the output G4 detected by the sensor S4, the acetylene concentration NC2H2, and the ethylene concentration NC2H4 is shown by Equation 4 which is the functional equation registered in the calculator 204. - 32 - G4 = 1+NC2H2/(NC2H2+NC2H4)-A41-(NC2H2)B41+NC2H4/ (NC2H2+NC2H4) A42-(NC2H4 )B42................................ (Equation 4) Here A41, A42, B41 and B42 are constants obtained by measuring a gas mixture of acetylene and air and a gas mixture of ethylene and air using the sensor S4. The ethylene concentration NC2H2 is obtained by calculations by substituting the output of the sensor S4 for the acetylene concentration first obtained in G4 in equation 4 of the calculator 204. Next, in the case where the methane concentration NCH4 and the ethane concentration NC2H6 are obtained from the sample gas, the calibration curve for the output G5 of the sensor S5, the hydrogen concentration NH2, the carbon monoxide concentration NCO, the acetylene concentration NC2H2, the ethylene concentration NC2H4 and the ethane concentration NC2H6 is shown by Equation 5 which is the functional equation recorded in the calculator 205. G5=1+A51-NH2/(NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4)-(NH2)B51 +A52-NCO/(NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4)(NCO)B52 +A53-NC2H2/(NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4)-(NC2H2)B53 +A54-NC2H4/(NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4)-(NC2H4)B54 +A55-NCH4/ (NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4) -(NCH4 )B55 +A56-NC2H6/(NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4)-(NC2H6)B56 ..............................................(Equation 5) Here A51, A52, A53, A54, A55, A56, B51, B52, B53, B54, - 33 - B55, and B56 are constants obtained by measuring a gas mixture of hydrogen and air, a gas mixture of carbon monoxide and air, a gas mixture of acetylene and air, a gas mixture of ethylene and air, a gas mixture of methane and air, and a gas mixture of ethane and air using the sensor S5. In addition, in the case where the methane concentration NCH4 and the ethane concentration NC2H6 are obtained from the sample gas, the calibration curve for the output G6 of the sensor S6, the hydrogen concentration NH2, the carbon monoxide concentration NCO, the acetylene concentration NC2H2, the ethylene concentration NC2H4, the methane concentration NCH4, and the ethane concentration NC2H6 is shown by Equation 6 which is a separate functional equation recorded in the calculator 205. G6 = 1+A61-NH2/(NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4)-(NH2)B61 +A62-NCO/(NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4)-(NCO)B62 +A63-NC2H2/(NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4)-(NC2H2)B63 +A64-NC2H4/(NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4)-(NC2H4)B64 +A65-NCH4/ (NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4 )• (NCH4 )B65 +A66NC2H6/(NH2+NCO+NC2H2+NC2H4+NC2H6+NCH4)-(NC2H6)B66 ..................................................................... (Equation 6) Here A61, A62, A63, A64, A65, A66, B61, B62, B63, B64, B65, and B66 are constants obtained by measuring a gas mixture of hydrogen and air, a gas mixture of carbon - 34 - monoxide and air, a gas mixture of acetylene and air, a gas mixture of ethylene and air, a gas mixture of methane and air, and a gas mixture of ethane and air using the sensor S6. The output from sensor S5 and sensor S6 respectively are substituted for the previously obtained gas concentrations of NH2, NCO, NC2H2, NC2H4 in Equation 5 and Equation 6 in G5 of Equation 5 of the calculator 205 and G6 of Equation 6 of calculator 205 respectively to give simultaneous equations. By solving for NCH4 and NC2H6, the concentrations of methane and ethane can be obtained by calculation. The concentrations of hydrogen, carbon monoxide, methane, ethane, ethylene and acetylene are obtained by calculations as shown above. According to the embodiment of the present invention, a dissolved gas analyzer of insulating oil and a method for analyzing dissolved gas analyzer of insulating oil enable to detect the concentration of various gases with high detection repeatability using a general-use semiconductor is realized. [Embodiment 2 of the invention] Fig. 7 shows the structure of the dissolved gas analyzer of insulating oil of second embodiment of the present invention and this is a portable type of dissolved - 35 - gas analyzer of insulating oil which is used in a device that has insulating oil sealed inside. The dissolved gas analyzer of this embodiment performs dissolved gas analysis for hydrogen and acetylene. The dissolved gas analyzer 30 of insulating oil in this embodiment which is shown in Fig. 7 shares the same basic structure as the first embodiment shown in Fig. 1, Fig. 3 and Fig. 4, and thus descriptions of the component parts that are the same will be omitted and only the parts that are different will be described. In Fig. 7, the inside of the device (not shown) that is required for dissolved gas analysis in the portable dissolved gas analyzer is filled with insulating oil 2. The dissolved gas analyzer 30 has an insulating oil injector 501, and by installing a gas extractor 3 which is connected to the insulating oil injector 501 via pipe 25C which has a valve 503, the gas generated in the insulating oil 2 that is sampled with the insulating oil injector 501 is extracted by using the bubbling method in the gas extractor 3. The insulating oil injector 501 has a cylinder shape and the insulating oil that is sealed in the device for analysis of dissolved gas is sampled and only a prescribed amount of the sampled insulating oil is supplied to the gas extractor 3. The bottom portion of the gas extractor 3 has - 36 - an oil discharge port 504 which includes a valve 502 and the insulating oil 2 from which the dissolved gas for analysis is extracted is discharged to the outside. There is an air purifier 31 which removes organic gases from the air that is taken from the atmosphere and pure air which is the sample gas and which has been purified and the humidity has been adjusted is led to the four-way switching valve 10 via the air supply pipe 18F. By switching the four-way switching valve 10, a flow path is formed which supplies pure air to the gas extractor 3 as inert gas from the air purifier 31 via the air supply pipe 18F and the gas extraction pipe 18C1. It is to be noted that an air pump which stores purified air may be used in place of the air purifier 31. Also, the four-way switching valve 10 is formed so as to connect the gas extraction pipe 18C2 which leads the gas mixture of dissolved gas generated in the insulating oil 2 from the gas extractor 3 with the dissolved gas mixture supply pipe 18D which leads dissolved gas mixture led via the gas extraction pipe 18C2 to the gas regulator 13. In addition, by switching the four-way switching valve 10, a flow path is formed in which a gas mixture of dissolved gases is caused to flow from the gas extractor 3 down to the thermostat 14 described hereinafter via the gas extraction pipe 18C2 and the dissolved gas mixture supply - 37 - pipe 18D and regulated at a prescribed temperature and then supplied to the gas detector 15. The gas extraction pipe 18C1 has an air pump 11 and by actuating the air pump 11, bubbling which is the same as that of the foregoing first embodiment of the present invention is performed. In addition, the gas extractor 3 has a filter 12 and when the gas mixture of dissolved gases generated in the insulating oil 2 is led from the gas extractor 3 to the four-way switching valve 10, the gas mixture of dissolved gases that has become atomized and mixed in the insulating oil is removed by the filter 12. The gas detector 15 has semiconductor sensors formed from metal oxides such as tin oxide, tungsten oxide, zirconium oxide and the gas mixture of nitrogen and oxygen which is the sample gas and the gas mixture of nitrogen, oxygen and the dissolved gases respectively are measured using the semiconductor sensors, and the measured values are output to the computer 16 as output signals. At the computer 116, the concentration of the gas components of the dissolved gas is calculated by computations based on the output signals from the semiconductor sensors disposed in the gas detector 15 and the calculated concentration of the gas components of the dissolved gas are displayed on a monitor and the like. The - 38 - computer 16 sends commands to the elements comprising the dissolved gas analyzer disposed in the insulating oil immersed transformer in the embodiment of this invention which include the ON and OFF for the pumps and the switching operations and open and close operations for the switch valve and the exhaust valves. Next, each of the steps in dissolved gas analysis of the portable dissolved gas analyzer of insulating oil which is the second embodiment of this invention shown in Fig. 7 is shown in Fig. 8. In the measuring operation in Fig. 8, first the measurement preparation step 111 is performed. Next, step 112 of dissolved gas extraction is performed. Step 112 of dissolved gas extraction is performed in parallel with the step 113 of measuring air gas which is the reference gas. Finally, step 114 of measuring the sample gas is performed. Step 115 of gas concentration calculation in which the concentration of each component gas is measured based on the measurement results from the step 113 of measuring air gas and the step 104 of measuring the sample gas is performed. Each of the steps in the measurement operation is repeated. To explain more specifically, in the step 111 of measurement preparation, the four-way switching valve 10 is operated as shown in Fig. 7 and purified air from the air purifier 31 is supplied to the four-way switching valve 10 - 39 - via the air supply pipe 18F. The purified air that is supplied flows from the air supply pipe 18F into the gas extractor 3 from the gas extraction pipe 18C1 via the four-way switching valve 10. Subsequently, purified air passes through the gas extractor 3 and flows down to the gas extraction pipe 18C2 and the dissolved gas mixture supply pipe 18D, and the inside of the devices and the flow paths which reach the dissolved gas mixture supply pipe 18D from the air supply pipe 18F are displaced with pure air. Next, in step 112 of dissolved gas extraction, as shown in Fig. 9, the four-way switching valve 10 is operated and switching is done. In addition, by switching the four-way switching valve 10, the flow path A forms a closed system with the gas extraction pipe 18C1, the gas extraction pipe 18C2, and the gas extractor 3. Also, by switching the four-way switching valve 10, a flow path B is formed which supplies purified air from the air purifier 31 to the thermostat 14 via the air supply pipe 18F and the four-way switching valve 10. In addition, the purified air which flows down the flow path B in the thermostat 14 is adjusted to a set temperature and forms the purified air which will become the reference gas and the purified air which becomes the reference gas is supplied to the gas detector 15. - 40 - The gas extraction operation is performed in the flow path A. In the gas extraction in the flow path A, first the release valve 4 in the gas extractor 3 is put in the release state and the insulating oil 2 is injected by the insulating oil injector 201. Next, when injection of the insulating oil 2 into the gas extractor 3 is complete, the release valve 4 closes simultaneously and the air pump 11 in the gas extraction pipe 18C1 which forms the flow path A is actuated and the purified air in the flow path A is circulated and the dissolved gas that is dissolved in the insulating oil 2 that is injected in the extractor 3 by bubbling is extracted to the purified air and sampled to form the sample gas. Next, in the step 113 of measuring the air gas which is the reference gas, the purified air which is the reference gas is supplied from the air purifier 31 to the thermostat 14 via the flow path B formed by switching the four-way switching valve 10 and the temperature is adjusted and measurement is done at the gas detector 15. That is to say, purified air is supplied to the thermostat 14 from the air purifier 31 via the air supply pipe 18F and the four-way switching valve 10 and purified air which is the reference gas, and whose set temperature has been adjusted at the thermostat 14 is formed and - 41 - supplied to the gas detector 15. When the detected output becomes stable for the purified air which is the reference gas detected by the semiconductor sensors SI - S7 in the gas detector 15, the detected output is input to the computer 16 as sensor output for the purified air which is the reference gas. Next, in the sample gas measurement step 114, as shown in Fig. 10, the four-way switching valve 10 is switched and purified air from the air purifier 31 is supplied to the gas extractor 3 via the air supply pipe 18F, the four-way switching valve 10 and the gas extraction pipe 18C1 and the supplied purified air flows down to the thermostat 14 from the gas extractor 3 via the gas extraction pipe 18C2 and the dissolved gas mixture supply pipe 18D. According to this operation, the gas mixture of dissolved gases which was sampled from the flow path A is pushed out by the purified air supplied from the purifier 31 and led to the thermostat 14 via the four-way switching valve 10. The gas mixture of the dissolved gases that is led to the thermostat 14 forms the sample gas whose set temperature is adjusted at the thermostat 14. In addition, the generated sample gas is supplied to the gas detector 15 and the concentration of the sample gas is detected. By switching from the gas that is supplied to the - 42 - semiconductor sensor S1, S3 and S4 in the gas detector 15 from air which is the reference gas to the sample gas, the sensor output of the sample gas detected by the semiconductor sensors S1, S3 and S4 changes significantly around the time the supplied gas is switched. When the sensor output is substantially stable after the changes in sensor output, the output of these sensors is input to the computer 16 as the sensor outputs for the semiconductor sensors S1, S3 and S4 for the sample gas. The sensor output for the reference gas and sample gas detected by the semiconductor sensor S1, S3 and S4 provided in the gas detector 15 is not shown in the drawing, but it is the same as that in Fig. 5. In addition, if the electrical resistance RO of the sensor output for the reference gas and the electrical resistance Rl of the sensor output for the gas for measurement in the sample gas and if the proportion R0/R1 of both sensor outputs at computer 16 are compared, the gas concentration of the gases to be measured in the sample gas can be accurately calculated. Fig. 11 shows a block diagram for calculating the gas concentration of the various dissolved gases dissolved in the sample gas detected by the semiconductor sensors S1, S3 and S4 disposed in the gas detector 15 in the dissolved gas analyzer of insulating oil in the second embodiment of the - 43 - present invention shown in Fig. 7 to Fig. 10 and the sensor output for the sample gas are input into the computer 16 and the gas concentration of each gas in the sample gas to be detected are calculated. As is the case in the first embodiment of the present invention, the electrical resistance R which is the sensor output from the semiconductor sensors S1, S3 and S4 for the reference gas and each gas to be detected at a specific concentration is obtained in advance to correspond with the reference gas and each of the gases to be detected. In Fig. 11, the concentration of the gas components to be measured that are included in the sample gas are calculated by the calculator 301, calculator 303 and calculator 304 that are installed in the computer 16 based on the output detected by the plurality of semiconductor sensors SI, S3 and S4 which have different properties for the purified air which is the reference gas and the sample gas. The semiconductor sensor used is preferably which reacts with few types of gases. In the step for calculating the gas concentration of each type of gas included in the sample gas to be measured, first the gas concentration of gas components for which the concentration can be obtained using the output detected with a small number of semiconductor sensors from among the semiconductor sensors S1, S3 and S4. - 44 - Next, by substituting the concentration of the gas components that were obtained first into a calculation formula that shows the relationship between the reaction properties and gas concentration, an unknown gas concentration is calculated from the output detected using the remaining semiconductor sensors. This calculation is repeated to obtain the other unknown gas concentrations and the number of unknown gas concentrations is gradually decreased until the concentration of all the gas components are finally obtained. In this embodiment of the present invention, the concentration are calculated in the order of hydrogen, acetylene, and ethylene are calculated in that order. Of the semiconductor sensors S1, S3 and S4, by first obtaining the gas concentration of gas components for which the concentration can be obtained using a small number of semiconductor sensors from among the semiconductor sensors S1, S3 and S4, the amount of calculations for the gas concentration computations can be reduced and the detection accuracy for the gas to be detected is increased. In addition, in the block diagram for calculating the gas concentration of the various dissolved gases shown in Fig. 11, the calculation values for the gas concentrations of hydrogen, acetylene and ethylene, that are included in the sample gas and calculated using the calculator 301, - 45 - calculator 303 and calculator 304 are input in the monitoring device 310 and can be monitored at all times. In this case, if the permissible values for gas concentrations to be detected are input from the setting device 320 to the monitoring device 310, it becomes possible for a warning to be given at the monitoring device 310 for gas concentrations to be detected which exceed the permissible values. In addition, the gas concentrations to be detected and the warning displays from the monitoring device 310 can be displayed at the display device 330. Next, in this embodiment of the present invention, the gas concentration calculation method is described for the case where there is linearity between the concentrations of the gas for detection and the detection properties of the semiconductor sensors. In Fig. 11, the gas concentration calculations are described for the case where detection is done for purified air which is the reference gas and for the sample gas. First, in the case where the hydrogen concentration NH2 is obtained from the sample gas, the calibration curve (ratio of electrical resistance for detection concentration and sensor output) for the output Gl detected by the sensor SI and the concentration NH2 of the hydrogen which is the gas to be detected, is shown by the functional equation (Equation 7) which is registered at the calculator 301. - 46 - G1=1+A11-(NH2)B11 ........................................ (Equation 7) Here All and Bll are constants obtained by measuring a gas mixture of hydrogen and air using the sensor SI. The hydrogen concentration NH2 is obtained by substituting output detected by the sensor SI for Gl in Equation 7 of calculator 301. Next, in the case where the acetylene concentration NC2H2 is obtained from the sample gas, the calibration curve for the output G3 detected by the sensor S3, the acetylene concentration NC2H2, and the ethylene concentration NC2H4 is shown by Equation 8 which is the functional equation registered in the calculator 303. G3=1+NC2H2/ (NC2H2+NC2H4 )-A31-(NC2H2 )B31+NC2H4/ (NC2H2+NC2H 4)A32-(NC2H4)B32................................(Equation 8) Here A31, A32, B31 and B32 are constants obtained by measuring a gas mixture of acetylene and air and a gas mixture of ethylene and air using the sensor S3. Also, the calibration curve for the output G4 of the sensor S4, the acetylene concentration NC2H2, the ethylene concentration NC2H4 is shown by Equation 9 which is the functional equation registered in the calculator 304. G4 = 1+NC2H2/ (NC2H2+NC2H4) -A41-(NC2H2 )B41+NC2H4/ (NC2H2+NC2H 4)A42-(NC2H4)B42................................................ (Equation 9) Here A41, A42, B41 and B42 are constants obtained by measuring a gas mixture of acetylene and air and a gas - 47 - mixture of ethylene and air using the sensor S4. The output from each of sensor S3 and sensor S4 is substituted for G3 in Equation 8 which is the functional equation for the calculator 303 and for G4 in Equation 9 which is the functional equation for the calculator 304. By solving for NCH4 and NC2H6, the concentration of the ethylene and acetylene are obtained by calculation. The concentration of hydrogen and acetylene respectively can be obtained by calculations as shown above. [Embodiment 3 of the invention] The third embodiment of the present invention is a dissolved gas monitoring system which monitors analysis of the dissolved gas sealed in an insulating oil-immersed transformer by monitoring multiple oil immersed transformers all at once. Fig. 12 shows the dissolved gas monitoring system in this embodiment of the present invention where a plurality of insulating oil immersed transformers is monitored at once. The dissolved gas analyzer of insulating oil with communication means 401, 402 and 403 and the central monitoring device 420 can communicate via the telephone circuit 430, the cellular phone circuit 450 and/or the wireless 440. The dissolved gas analyzers of insulating oil with communication means 401, 402 and 403 each comprises an - 48 - insulating oil immersed transformer 1; dissolved gas analyzers of insulating oil 20 and 30 for sampling each kind of gas included in the insulating oil 2 sealed in the oil immersed transformer 1 and monitoring devices 210 and 310 for monitoring each type of gas detected at the dissolved gas analyzer of insulating oil 20 and 30. In addition, the dissolved gas analyzers of insulating oil with communication means 401, 402 and 403 are connected by a LAN to a HUB and the concentration of each of the gases sampled and analyzed at the dissolved gas analyzers of insulating oil 20 and 30 as well as the monitoring results data are transmitted to the central monitoring device 420. It is not usually necessary to send and receive the transmitted data since the data should be sent and received periodically. In the case where the reproducibillty of the data that is sent is to be checked, or the case where diagnostic results by monitoring is received and monitoring is to be strengthened, the central monitoring device 420 instructs dissolved gas analysis by re-measuring or reducing the measuring interval. In addition, if there is any abnormality in the diagnostic results, a more precise gas analysis may be performed or the insulating oil immersed transformer may be stopped. In addition, operation of the dissolved gas - 49 - analyzers of insulating oil with communication means 401, 402 and 403 or residual air amount in the air pump can be checked at the central monitoring device 420. This dissolved gas monitoring system is effective for a remotely set insulating oil immersed transformer or for monitoring insulating oil immersed transformers that are scattered over an area all at once. In addition, this system may be one in which the dissolved gas analyzers of insulating oil with communication means 401, 402 and 403 and the central monitoring device 420 are directly connected using LAN or a system in which each of the dissolved gas analyzers of insulating oil with communication means 401, 402 and 403 communicate directly with the central monitoring device 420 via a telephone circuit or cellular telephone circuit. In addition, the detection outputs of the semiconductors which detect gas concentration for each type of gas are received at the central monitoring device 420 and the gas concentration of each type of gas is calculated at the central monitoring device 420. According to this embodiment of the present invention, a dissolved gas analyzer of insulating oil and a method for analyzing dissolved gas analyzer of insulating oil enable to detect the concentration of various gases with high detection repeatability using a general-use semiconductor - 50 - is realized. [Embodiment 4 of the invention] The dissolved gas analyzer of insulating oil based on the membrane permeation method as the fourth embodiment of the present invention is provided with the insulating oil immersed transformer. In this embodiment, the dissolved gas analyzer with the membrane permeation method is applied to the insulating oil immersed transformer in stead of the gas extractor 3 of the dissolved gas analyzer which is shown in the first embodiment of invention. The connection method of this embodiment is as followings. That is, the gas extraction pipe 18C1 is connected to the carrier gas supply port described hereinafter and the gas extraction pipe 18C2 is connected to the carrier gas discharge port described hereinafter. The dissolved gas analyzer of insulating oil with the membrane permeation method of the fourth embodiment is explained referring the drawings as followings. In the dissolved gas analyzer of insulating oil with the membrane permeation method in this embodiment, time t until the concentration of decomposition gases in a gas reservoir in the dissolved gas analyzer reaches an equilibrium can be represented as in equation 10 below in which V, d and A are taken as the volume of the gas - 51 - reservoir, the thickness of the permeable membrane, and the area of the permeable membrane, respectively. P is a transmission coefficient and C is a constant. According to equation 10, when the thickness d of the gas permeable membrane and the volume V of the gas reservoir are made small and the area A of the gas permeable membrane is made large, the time t until an equilibrium is reached can be shortened. To shorten the time t until the equilibrium is reached, the thickness d of the permeable membrane is preferably made small. However, the gas permeable membrane is often attached to the oil discharge port of the oil immersed transformer, and the insulating oil applies a pressure about 0.2 MPa to the position at which the gas permeable membrane is attached. If the gas permeable membrane is too thin, it is broken. Suppose that a gas permeable membrane with a thickness of dl is used for a discoidal hollow gas reservoir in a groove shape with an outer radius of R1 + r and an inner radius of R1 - r. A pressure p applied to the gas permeable membrane and a shear stress tl applied to the circumference of the gas permeable membrane can be represented as in equation 11 below. - 52 - When the pressure p applied to the gas permeable membrane is 0.2 MPa and an allowable shear stress is x, the relation between the width 2r of the groove and the thickness d of the gas permeable membrane is determined by equation 12 below. r Accordingly, it is preferable in tis embodiment of the invention that the thickness of the gas permeable membrane is thinned by determining the width of the groove-shaped gas reservoir so that the relation among the allowable maximum shear stress x (MPa) of the material of the gas permeable membrane, the width 2r of the groove, and the thickness d of the gas permeable membrane satisfies equation 12. To increase precision in gas measurement, it is preferable that the sample gas, which is held in the gas reservoir and used for analysis, can be supplied to a gas detector without being diluted by nitrogen gas or a carrier gas as inert gas. Accordingly, this embodiment of the invention proposes that the cross sectional area of the groove of the gas reservoir is equal to or smaller than the - 53 - cross sectional area of the carrier gas inlet port, thereby preventing the gas in the gas reservoir from being diluted by the carrier gas. When the volume of the groove, which is the gas reservoir, is equal to the amount of sample gas needed for the gas measurement by the gas detector, it is possible to measure a fixed amount of gas in the gas reservoir, enabling a predetermined amount of sample gas to be always supplied without having to provide a fixed-volume measurement pipe. In this case, the carrier gas supply port and carrier gas discharge port are preferably disposed at ends of the groove-shaped gas reservoir to supply the predetermined amount of sample gas. The dissolved gas analyzer in this embodiment of the invention preferably has an oil flow means for having oil flow by agitating or vibrating the insulating oil. When the decomposition gases included in the insulating oil are transmitted to the gas reservoir, the concentration of the decomposition gases included in the insulating oil becomes locally low near the gas permeable membrane, lowering the efficiency of the gas permeation. When the insulating oil is agitated or vibrated so that it flows, the concentration of the decomposition gases in the insulating oil can be made uniform, increasing the efficiency of the gas permeation. The time t until an equilibrium is reached can - 54 - be thus shortened. A high-molecular organic compound membrane or high- molecular organic compound porous membrane can be used as the material of the gas permeable membrane. A porous plate, perforated plate, or wire mesh can be integrated with the high-molecular organic compound membrane or high-molecular organic compound porous membrane as a reinforcing member. In this embodiment of the invention, a dissolved gas analyzer for an oil immersed transformer will be described. FIG. 13 shows the structure of a gas extracting unit 3 in the dissolved gas analyzer of insulating oil. The gas extracting unit 3 comprises a grooved flange 1101, a gas permeable membrane 1102, a groove-shaped gas reservoir 1103, a carrier gas supply port 1104, a carrier gas discharge port 1105, a valve 1106a, and another valve 1106b. An oil discharge port 1201 and an oil discharge valve 1202 are both disposed on the oil immersed transformer side. Although the oil discharge port 1201 and oil discharge valve 1202 are originally used as a port for discharging unnecessary insulating oil, they are used to attach the gas extracting unit 3 in this embodiment. When a gas is extracted, the oil discharge valve 1202 is left open and the gas permeable membrane 1102 is in close contact with an insulating oil 1203. When the grooved flange 1101 is fastened to the oil - 55 - discharge port 1201, the gas extracting unit 3 is attached to an oil immersed transformer 1 and the gas permeable membrane 1102 is fixed by being supported from the circumference thereof. The gas permeable membrane 1102 seals the insulating oil 1203 into the insulating oil immersed transformer or an external container of the insulating oil immersed transformer, and allows decomposition gases to transmit to the groove-shaped gas reservoir 1103. The material of the gas permeable membrane 1102 is a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, with a thickness of 0.1 mm. Preferable materials of the gas permeable membrane 1102 include tetrafluoro copolymer membranes, high-molecular organic compound membranes made of polyethylene and fluorine rubber, high-molecular organic compound porous membranes, porous plates coated with high- molecular organic compounds, and high-molecular organic compound membranes reinforced by perforated plates or wire meshes. The groove-shaped gas reservoir 1103 is a grooved- shaped recession formed in the grooved flange 1101. The groove-shaped gas reservoir 1103 is a space defined by the gas permeable membrane 1102 and is used to extract and store a sample gas. When the sample gas is supplied, the groove-shaped gas reservoir 1103 serves as a path through - 56 - which the carrier gas flows. The carrier gas supply port 1104 communicates with an end of the groove-shaped gas reservoir 1103 and serves as an inlet port through which the carrier gas enters in the groove-shaped gas reservoir 1103. The area of the cross section of the groove-shaped gas reservoir 1103 perpendicular to the streamline of the carrier gas is smaller than the area of the cross section of the carrier gas supply port 1104 perpendicular to the streamline of the carrier gas. The carrier gas discharge port 1105 communicates with the other end of the groove-shaped gas reservoir 1103 and serves as an outlet port through which the extracted and stored sample gas and the carrier gas supplied through the carrier gas supply port 1104 are discharged. The valve 1106a and valve 1106b are closed when the sample gas is extracted and stored; they are opened when the sample gas in the gas reservoir is replaced with the carrier gas. A packing 1107 is inserted into a joint between the grooved flange 1101 and the gas permeable membrane 1102 and another packing 1107 is inserted into a joint between the oil discharge port 1201 and the gas permeable membrane 1102. The packings 1107 contribute to the sealing of the insulating oil into the insulating oil immersed transformer - 57 - or its external vessel. FIG. 14 shows the structure of the grooved flange of the dissolved gas analyzer of insulating oil. The groove- shaped gas reservoir 1103 in the drawing is linearly structured. The area of the cross section of the groove- shaped gas reservoir 1103 perpendicular to the streamline of the carrier gas is preferably equal to or smaller than the area of the cross section of the carrier gas supply port so that the carrier gas is supplied without turbulence or the sample gas is not mixed with the carrier gas. FIG. 16 shows a procedure for analyzing gases dissolved in the insulating oil. Steps for dissolved gas analysis include preparation for extracting a sample gas, the extraction and storage of the sample gas, preparation for measurement, supply of the sample gas, and sample gas measurement. In the step of preparing for extracting a sample gas, a carrier gas is substituted in the groove-shaped gas reservoir 1103. Specifically, the carrier gas is supplied from the carrier gas supply unit with the valve 1106a and valve 1106b open. The sample gas is then extracted and stored. When the carrier gas has been substituted in the groove-shaped gas reservoir 1103, the valve 1106a and valve 1106b are closed. Discomposed gases dissolved in the insulating oil transmit - 58 - through the gas permeable membrane 1102 and diffuse in the groove-shaped gas reservoir 1103. It is awaited until an equilibrium between the concentration of the gas in the groove-shaped gas reservoir 1103 and the concentration of the decomposition gases in the insulating oil is reached. A time for the gas concentration to reach the equilibrium is obtained in advance by performing measurement test. When the constant C in equation 10 is known, the time to reach the equilibrium may be estimated from equation 10. Preparation for measurement is then made. A carrier gas is supplied from the carrier gas supply unit to the gas detector unit. The next step is to supply a sample gas. The valve 1106a and valve 1106b are opened and a carrier gas is then supplied from the carrier gas supply unit through the gas extracting unit to the gas detector unit. The carrier gas is substituted in the groove-shaped gas reservoir 1103, supplying the sample gas that has been in the groove-shaped gas reservoir 1103 to the gas detector unit, where the types and concentrations of gases are measured. [Embodiment 5 of the invention] In this embodiment of the present invention, a case in which the sample gas is extracted, stored, measured, and - 59 - supplied in the groove-shaped gas reservoir 103 will be described with reference to FIGs. 14 to 16. Since a fixed volume of sample gas is measured in the groove-shaped gas reservoir 1103, a fixed-volume measurement pipe does not need to be prepared separately, saving the volume of the fixed-volume measurement pipe itself and the pipe to the fixed-volume measurement pipe. Accordingly, in equation 10, the volume V of the gas reservoir can be made small and the time t to reach the equilibrium can be shortened. The carrier gas supply port 1104 in FIG. 14 is cylindrical, the radius being r. The groove-shaped gas reservoir 1103 is a rectangular parallelepiped with a length of L, a width of 2r, and a groove depth of h. Both end of the groove-shaped gas reservoir 1103 are semi- cylindrical column with a radius of r and a depth of h. The volume of the groove-shaped gas reservoir 1103 is thereby 2rLh + πr2h. The volume of the groove-shaped gas reservoir 1103 is equal to the volume of the supplied sample gas. Accordingly, the volume of the groove-shaped gas reservoir 1103 was made equal to the volume of a sample gas required for measurement. The area 2rh of the cross section of the groove-shaped gas reservoir 1103 perpendicular to the streamline of the carrier gas is 10 mm2, which is smaller than the cross - 60 - sectional area jtr2 of the carrier gas supply port 1104 which measures 19.6 mm2. According to the dissolved gas analysis procedure, a carrier gas was first substituted in the groove-shaped gas reservoir 1103, as preparation for gas extraction. Specifically, the carrier gas was supplied from the carrier gas supply unit with the valve 1106a and valve 1106b open. The sample gas was then extracted and stored. After the carrier gas has been substituted in the groove-shaped gas reservoir 1103, the valve 1106a and valve 1106b are closed and left in that state. Discomposed gases dissolved in the insulating oil transmit through the gas permeable membrane 1102 and diffuse in the groove-shaped gas reservoir 1103. It was awaited until the concentration of the gas in the groove-shaped gas reservoir 1103 reached an equilibrium. A time for the gas concentration to reach the equilibrium was obtained in advance by performing measurement test, which was preset to 70 hours. When a fixed-volume measurement pipe was provided separately, not according to the present embodiment of the invention, the time for the gas concentration to reach the equilibrium was 138 hours. Accordingly, the time taken for gas extraction could be halved. After the gas concentration reached the equilibrium. - 61 - preparation for measurement was then made. A carrier gas was supplied from the carrier gas supply unit to the gas detector unit. The next step was to supply a sample gas. The 1106a and valve 1106b were opened and a carrier gas was supplied from the carrier gas supply unit through the gas extracting unit to the gas detector unit. The carrier gas was substituted in the groove-shaped gas reservoir 1103, supplying the sample gas that had been in the groove-shaped gas reservoir 1103 to the gas detector unit. [Embodiment 6 of the invention] In the Fifth embodiment of the present invention, a case in which the width of the groove-shaped gas reservoir 1103 is adjusted so as to reduce the thickness of the gas permeable membrane will be described. FIG. 15 shows the structure of a grooved flange having an arc-shaped gas reservoir. This embodiment of the present invention is compared with the conventional structure based on the conventional method; in the embodiment of the present invention, the groove-shaped gas reservoir 1103 is a cylindrical reservoir with an external radius of R1 + r, an internal radius of R1 - r, and a height of h, and the width of the gas permeable membrane 1102 is dl; in the conventional structure, the gas reservoir is a columnar - 62 - reservoir with a radius of R2 and a height of h, and the width of the gas permeable membrane 1102 is d2. In this embodiment of the present invention, it is assumed that a shear stress is uniformly applied to the circumference of the gas permeable membrane 1102. The shear stress t1 applied to the circumference of the gas permeable membrane 1102 is obtained from equation 11, as described above. Let t be an allowed shear stress. The thickness dl of the gas permeable membrane 1102 is then determined by equation 14. By comparison, in the conventional structure, the shear stress %2 applied to the circumference of the gas permeable membrane 1102 is determined by equation 15. Let t be an allowed shear stress. The thickness d2 of the gas permeable membrane 1102 is then determined by equation 16. A ratio dl/d2 between the membrane thicknesses is - 63 - represented as in equation 17; the ratio is determined by r and R2, independently of R1. Since V = A x h, equation 10 can be rewritten as equation 18. In the present embodiment of the invention, time tl to reach the equilibrium is represented as in equation 19. In the conventional structure, time t2 to reach the equilibrium is represented as in equation 20. A ratio tl/t2 between the times to reach the equilibrium is represented as in equation 21 from equations 17, 19, and 20; the ratio is determined by r and R2. When the area of the gas permeable membrane 1102 in the present embodiment of the invention is equal to the area of - 64 - the gas permeable membrane 1102 in the conventional structure, for example, R1, r, and R2 are respectively 50 mm, 2 mm, and 20 mm, the time tl to reach the equilibrium in the present embodiment of the invention can be reduced to one-fifth the time t2 to reach the equilibrium in the conventional structure. FIG. 16 shows the structure of a grooved flange having a gas reservoir in a zigzag shape as one of other embodiment of the invention. FIG. 17 shows the structure of a grooved flange having a gas reservoir in a spiral shape as one of other embodiment of the invention. The flange having a gas reservoir in a zigzag or spiral shape may be used instead of the grooved flange having an arc-shaped gas reservoir shown in FIG. 15. Since the gas reservoir is formed in a groove shape in the dissolved gas analyzer of insulating oil based on the membrane permeation method in this embodiment of the invention, the volume of the gas reservoir can be lessened and the thickness of the gas permeable membrane can be reduced. Accordingly, time until the concentration of the decomposition gases in the gas reservoir reaches an equilibrium state can be shortened and thus time taken to extract the decomposition gases in the gas reservoir can be shortened. According to the present embodiment of the - 65 - invention, a time interval can be shortened for the dissolved gas analyzer, enabling the transformer to undergo a real-time check for abnormality. This invention can be used in a dissolved gas analyzer of insulating oil for equipment such as an oil-filled transformer and a method for analyzing dissolved gas of insulating oil in equipment such as an oil-filled transformer - 66 - WHAT IS CLAIMED IS Claim 1. A dissolved gas analyzer of insulating oil comprising: a gas extractor to draw insulating oil from an oil-filled equipment, a gas detector having a plurality of semiconductor sensors for detecting concentration of a component gas from a plurality of component gases included in the insulating oil drawn into the gas extractor; a sample gas supply system for sampling the plurality of component gases in the insulating oil drawn into the gas extractor and supplying to the gas detector as the sample gas for measuring; a reference gas supply system for supplying a reference gas to be a reference for the detection values of the semiconductor sensors to the gas detector; a switch means for switching between the sample gas supply system and the reference gas supply system and supplying the component gases or the reference gas to the ,gas detector; and a calculation device for calculating the concentration of the plurality of component gases dissolved in the insulating oil based on the detection values measured using the plurality of semiconductor sensors in the gas detector for the sample gas and the reference gas. Claim 2. The dissolved gas analyzer of insulating oil according to Claim 1, wherein the calculation device calculates each of the concentrations of the component gases included in the sample gas based on the detection - 67 - value of the sample gas measured by the plurality of semiconductor sensors and the detection value for the reference gas measured using the plurality of semiconductor sensors. Claim 3. The dissolved gas analyzer of insulating oil according to Claim 2, wherein the calculation device calculates the concentrations of the component gases included in the sample gas based on the proportion of the detection value of the sample gas and the detection value for the reference gas measured by the plurality of semiconductor sensors. Claim 4. The dissolved gas analyzer of insulating oil according to Claim 1 or Claim 2, wherein a gas mixture of oxygen and inert gas or air is used as the reference gas supplied by the reference gas supply system. Claim 5. The dissolved gas analyzer of insulating oil according to Claim 1 or Claim 2, further comprising a gas regulator for generating the sample gas to be supplied to the gas detector by adding oxygen to the gas mixture of the inert gas and dissolved gas sampled from the insulating oil by leading inert gas into the insulating oil in the gas extractor by bubbling Claim 6. The dissolved gas analyzer of insulating oil according to Claim 1 or Claim 2, further comprising an adjustor for ajusting the temperature of the sample gas and - 68 - the reference gas at a prescribed value. Claim 7. The dissolved gas analyzer of insulating oil according to Claim 1 or 2, wherein the calculation device calculates the gas concentration of a specific component gas in the sample gas from the detection value detected by the first sensor group of the plurality of semiconductor sensors disposed in the gas detector, and calculates the gas concentration of the remaining component gas in the sample gas from the detection value detected by the second sensor group of the plurality of semiconductor sensors disposed in the gas detector and the gas concentration of the specified component gas detected by the first sensor group, thereby obtaining the concentration of the plurality of component gases in the sample gas. Claim 8. The dissolved gas analyzer of insulating oil according to Claim 1 or 7, further comprising a monitoring device for monitoring the concentration of the plurality of component gases dissolved in the insulating oil, which was calculated by the calculation device. Claim 9. The dissolved gas analyzer of insulating oil according to Claim 8, further comprising a communication means for transmitting the state of monitoring of the concentration of the plurality of component gases dissolved in the insulating oil in the monitoring device. Claim 10. A method of analyzing dissolved gas of - 69 - insulating oil comprising the steps of: drawing insulating oil stored in an oil-filled equipment and supplying the insulating oil to a gas extractor; sampling a plurality of component gases included in the insulating oil drawn in the gas extractor and then allowing supply to a gas detector via a sample gas supply system as a sample gas to be measured; allowing a reference gas to be the detection value of the plurality of semiconductor sensors provided in a gas detector to be supplied to the gas detector via the reference gas supply system; switching between the sample gas to be supplied via the sample gas supply system and the reference gas to be supplied via the reference gas supply system and supplying to the gas detector; detecting the concentration of component gas from the plurality of components gas included in the sample gas and the concentration of the reference gas by the plurality of semiconductor sensors provided in the gas detector; and calculating the concentration of the plurality of component gases included in sample gas based on each of the detection values measured by the plurality of semiconductor sensors in the gas detector for the sample gas and the reference gas. Claim 11. The method of analyzing dissolved gas of insulating oil according to Claim 10, wherein the each of the calculations for the concentrations of the component - 70 - gases included in the sample gas is obtained based on the detection values of the sample gas measured by the plurality of semiconductor sensors and the detection values for the reference gas measured by the plurality of semiconductor sensors. Claim 12. A dissolved gas analyzer of insulating oil according to Claim 1, further comprising a gas permeable membrane attached to an oil discharge port of the the gas extractor, a gas reservoir provided in contact with the gas permeable membrane to store a gas therein transmitted through the gas permeable membrane, a carrier gas supply port and a carrier gas discharge port provided with the gas reservoir respectively so that the gas stored in the gas reservoir is discharged from the gas reservoir to the gas detector by supplying a carrier gas, and the gas reservoir is formed with a groove shape. Claim 13. The dissolved gas analyzer of insulating oil according to claim 12, wherein the gas reservoir is a grooved-shaped path to interconnect the carrier gas supply port and the carrier gas discharge port. Claim 14. The dissolved gas analyzer of insulating oil according to claim 12, wherein the cross sectional area of the groove of the gas reservoir with a groove shape is equal to or smaller than the cross sectional area of the carrier gas supply port. - 71 - Claim 15. The dissolved gas analyzer of insulating oil according to claim 12, wherein the volume of the gas reservoir is equal to the amount of sample gas required for a gas measurement by the gas detector. Claim 16. The dissolved gas analyzer of insulating oil according to claim 12, further comprising a pipe communicating between the carrier gas exhaust port disposed in the gas reservoir and the gas detector so that a sample gas discharged from the carrier gas exhaust port is supplied to the gas detector. Claim 17. The dissolved gas analyzer of insulating oil according to claim 16, wherein the groove of the gas reservoir has one of a straight line shape, an arc shape, a zigzag shape, or a spiral shape, and the carrier gas supply port is disposed at one end of the groove and the carrier gas exhaust port is disposed at the other end of the groove. Claim 18. The dissolved gas analyzer of insulating oil according to claim 12, wherein the calculation device calculates each of the concentrations of the component gases included in the sample gas based on the detection value of the sample gas measured by the plurality of semiconductor sensors and the detection value for the reference gas measured by the plurality of semiconductor sensors. A dissolved gas analyzer of insulating oil comprising: a gas extractor 3 to draw insulating oil 2 from an oil- filled equipment 1, a gas detector 15 having a plurality of semiconductor sensors sl-S7 for detecting concentration of a component gas from a plurality of component gases included in the insulating oil 2 drawn into the gas extractor 3; a sample gas supply system for sampling the plurality of component gases in the insulating oil 2 drawn into the gas extractor 3 and supplying to the gas detector 15 as the sample gas for measuring; a reference gas supply system for supplying a reference gas to be a reference for the detection values of the semiconductor sensors sl-s7 to the gas detector 15; a switch means 10 for switching between the sample gas supply system and the reference gas supply system and supplying the component gases or the reference gas to the gas detector 15; and a calculation device 201-205 for calculating the concentration of the plurality of component gases dissolved in the insulating oil 2 based on the detection values measured by the plurality of semiconductor sensors sl-s7 in the gas detector 15 for the sample gas and the reference gas. |
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00747-kol-2007-correspondence others 1.1.pdf
00747-kol-2007-correspondence others 1.2.pdf
00747-kol-2007-correspondence others 1.3.pdf
00747-kol-2007-correspondence others 1.4.pdf
00747-kol-2007-correspondence others.pdf
00747-kol-2007-description complete.pdf
00747-kol-2007-priority document 1.1.pdf
00747-kol-2007-priority document.pdf
747-KOL-2007-(02-09-2013)-CORRESPONDENCE.pdf
747-KOL-2007-(02-09-2013)-OTHERS.pdf
747-KOL-2007-(24-07-2012)-CORRESPONDENCE.pdf
747-KOL-2007-(24-07-2012)-FORM-6-1.pdf
747-KOL-2007-(24-07-2012)-FORM-6.pdf
747-KOL-2007-(24-07-2012)-OTHERS.pdf
747-KOL-2007-(24-07-2012)-PA.pdf
747-KOL-2007-(25-04-2013)-CORRESPONDENCE.pdf
747-KOL-2007-(25-04-2013)-FORM 1.pdf
747-KOL-2007-(25-04-2013)-FORM 13.pdf
747-KOL-2007-(25-04-2013)-FORM 2.pdf
747-KOL-2007-(25-04-2013)-FORM 3.pdf
747-KOL-2007-(25-04-2013)-FORM 5.pdf
747-KOL-2007-(25-04-2013)-OTHERS.pdf
747-KOL-2007-(25-04-2013)-PETITION UNDER SECTION 8(1).pdf
747-KOL-2007-(30-08-2013)-CORRESPONDENCE.pdf
747-KOL-2007-(30-08-2013)-OTHERS.pdf
747-KOL-2007-CORRESPONDENCE.pdf
| Patent Number | 263132 | |||||||||||||||
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| Indian Patent Application Number | 747/KOL/2007 | |||||||||||||||
| PG Journal Number | 41/2014 | |||||||||||||||
| Publication Date | 10-Oct-2014 | |||||||||||||||
| Grant Date | 08-Oct-2014 | |||||||||||||||
| Date of Filing | 14-May-2007 | |||||||||||||||
| Name of Patentee | JAPAN AE POWER SYSTEMS CORPORATION | |||||||||||||||
| Applicant Address | 8-3, NISHI-SHIMBASHI 3-CHOME, MINATO-KU, TOKYO | |||||||||||||||
Inventors:
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| PCT International Classification Number | G01N33/28 | |||||||||||||||
| PCT International Application Number | N/A | |||||||||||||||
| PCT International Filing date | ||||||||||||||||
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