CN105866055A - Method for diagnosing oil-filled electrical equipment - Google Patents
Method for diagnosing oil-filled electrical equipment Download PDFInfo
- Publication number
- CN105866055A CN105866055A CN201610181130.9A CN201610181130A CN105866055A CN 105866055 A CN105866055 A CN 105866055A CN 201610181130 A CN201610181130 A CN 201610181130A CN 105866055 A CN105866055 A CN 105866055A
- Authority
- CN
- China
- Prior art keywords
- gas
- detected
- oil
- spectrum
- single spectrum
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000001228 spectrum Methods 0.000 claims abstract description 38
- 238000003745 diagnosis Methods 0.000 claims description 9
- 239000011521 glass Substances 0.000 claims description 9
- 238000012545 processing Methods 0.000 claims description 6
- 238000002329 infrared spectrum Methods 0.000 claims description 5
- 230000003287 optical effect Effects 0.000 claims description 4
- 239000007789 gas Substances 0.000 abstract description 40
- 239000003921 oil Substances 0.000 abstract description 31
- 238000009413 insulation Methods 0.000 abstract description 4
- 239000002480 mineral oil Substances 0.000 abstract description 2
- 235000010446 mineral oil Nutrition 0.000 abstract description 2
- 238000012844 infrared spectroscopy analysis Methods 0.000 abstract 1
- 239000000126 substance Substances 0.000 abstract 1
- 238000000411 transmission spectrum Methods 0.000 abstract 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N Acetylene Chemical compound C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 14
- 229930195733 hydrocarbon Natural products 0.000 description 11
- 150000002430 hydrocarbons Chemical class 0.000 description 11
- 239000004215 Carbon black (E152) Substances 0.000 description 10
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 6
- 229910002091 carbon monoxide Inorganic materials 0.000 description 6
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 5
- 239000001257 hydrogen Substances 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 5
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 238000002835 absorbance Methods 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000011088 calibration curve Methods 0.000 description 1
- VTVVPPOHYJJIJR-UHFFFAOYSA-N carbon dioxide;hydrate Chemical compound O.O=C=O VTVVPPOHYJJIJR-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000002828 fuel tank Substances 0.000 description 1
- 230000013632 homeostatic process Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
A method for diagnosing oil-filled electrical equipment comprises the following steps: 1, determining insulation oil extracted from the oil-filled electrical equipment in a running state through adopting an infrared spectroscopic analysis system; 2, placing a gas to be detected in a Michelson interference light path, and moving a moveable mirror to obtain intensity changing interference waves on a detector in order to obtain a gas-to-be-detected interferogram; 3, carrying out Fourier transform on a background interferogram and the gas-to-be-detected interferogram to obtain a background single spectrum and a gas-to-be-detected spectrum in order to obtain a gas-to-be-detected transmission spectrum; and 4, obtaining a ratio of the background single spectrum to the gas-to-be-detected single spectrum according to results obtained in step 3. The oil-filled electrical equipment in a running state is analyzed, and the concentrations of various gases contained in mineral oil at the running beginning moment and used as reasonable substances are estimated, so the fault reasons of the oil-filled electrical equipment can be analyzed and checked.
Description
Technical field
The present invention is mainly fault diagnosis technical field, the method refering in particular to the diagnosis of a kind of oil-filled electric equipment.
Background technology
Under normal circumstances, the insulating oil of charging inside electric appliance and organic insulation are in heat with under the effect of electricity, and meeting is the most aging and decomposes a small amount of various low molecular hydrocarbons of generation and the gas such as carbon dioxide, carbon monoxide.These gas major parts are dissolved in oil.When having that latency is overheated or during discharge fault, the generation speed of these gases will be accelerated.Along with the development of fault, the bubble that the gas decomposited is formed, in oil back warp convection current, diffusion, is constantly dissolved in oil.The order of severity of the component of failure gas and mass fraction and fault has substantial connection.Therefore, in oil-filled electric equipment running, the gas in periodic analysis dissolved oil, can the internal Hidden fault existed of discovering device grasp the development of fault at any time as early as possible.Meanwhile, different with quantity according to the component producing gas, sentence the character knowing fault, with the generation of Accident prevention.
Summary of the invention
According to langbobier law, absorbance A and gas concentration c to be detected, Dewar bottle optical length l, GAS ABSORPTION rate a to be detected is directly proportional, i.e. A=acl.Utilize pure gas to be detected to set up the absorbance A calibration curve relative to concentration c at selected wave number, then can solve the content of unknown component according to the absorbance of gas to be detected to be measured.For accurate recovery spectrum, the present invention is provided with a set of infrared spectrum analysis system according to according to langbobier law, and according to the method that this system provides the diagnosis of a kind of oil-filled electric equipment.
Technical scheme is as follows:
The method of a kind of oil-filled electric equipment diagnosis, is characterized in that comprising the steps:
The step 1) insulating oil to extracting from operating oil-filled electric equipment uses the operation that infrared spectrum analysis system is measured；
Step 2) gas to be measured is placed in michelson interferometer optical path, will obtain the interference wave that intensity is continually changing during mobile index glass on detector；Obtain gas interference pattern to be detected；
Step 3) background interference figure and gas interference pattern to be detected are fourier transformed；Obtain background single spectrum and gas single spectrum to be detected, thus obtain gas transmitted spectrum to be detected；
Step 4) obtains background single spectrum and the ratio relation of gas single spectrum to be detected according to the result in step 3).
Method as above, in described step 4), the ratio relation of background single spectrum and gas single spectrum to be detected obtains according to gas transmitted spectrum to be detected.
Method as above, described step 2) mid-infrared light analysis of spectrum system is made up of data acquisition processing system, detector, Dewar bottle, beam splitter, horizontal glass, light source, index glass, and Dewar bottle connects detector, and detector connects data acquisition processing system.
Method as above, draws the content transformed value of each gas, thus judges fault and the fault type of oil-filled electric equipment according to the ratio relation of background single spectrum and gas single spectrum to be detected.
Method as above, in described step 1), insulating oil is placed in Dewar bottle under vacuum, and heats the gas to be detected in Dewar bottle, and keeps constant temperature 30 °～45 °.
Method as above, described gas to be detected keeps constant temperature 35 °.
The invention have the benefit that
In the method to oil-filled electric equipment fault diagnosis of the present invention, by operating oil-filled electric equipment is analyzed, the concentration of the various gases at starting time mineral oil be included as reason material is estimated, it is thus possible to the failure cause in this oil-filled electric equipment in the future is analyzed and investigates.
Accompanying drawing explanation
Accompanying drawing described herein is used for providing a further understanding of the present invention, constitutes the part of the application, is not intended that inappropriate limitation of the present invention, in the accompanying drawings:
The flow chart of the method for the oil-filled electric equipment diagnosis that Fig. 1 provides for the present invention；
The system construction drawing of the infrared spectrum analysis system that Fig. 2 provides for the present invention.
Detailed description of the invention
Describing the present invention in detail below in conjunction with accompanying drawing and specific embodiment, illustrative examples and explanation in this present invention are used for explaining the present invention, but not as a limitation of the invention.
With reference to Fig. 1, the method for a kind of oil-filled electric equipment diagnosis, it is characterized in that comprising the steps:
The step 1) insulating oil to extracting from operating oil-filled electric equipment uses the operation that infrared spectrum analysis system is measured；
Step 2) gas to be measured is placed in michelson interferometer optical path, will obtain the interference wave that intensity is continually changing during mobile index glass 7 on detector 2；Obtain gas interference pattern to be detected；
Step 3) background interference figure and gas interference pattern to be detected are fourier transformed；Obtain background single spectrum and gas single spectrum to be detected, thus obtain gas transmitted spectrum to be detected；
Step 4) obtains background single spectrum and the ratio relation of gas single spectrum to be detected according to the result in step 3).
Method as above, in described step 4), the ratio relation of background single spectrum and gas single spectrum to be detected obtains according to gas transmitted spectrum to be detected.
Method as above, described step 2) mid-infrared light analysis of spectrum system is made up of data acquisition processing system 1, detector 2, Dewar bottle 3, beam splitter 4, horizontal glass 5, light source 6, index glass 7, described Dewar bottle 3 connects detector 2, and detector 2 connects data acquisition processing system 1.
Method as above, draws the content transformed value of each gas, thus judges fault and the fault type of oil-filled electric equipment according to the ratio relation of background single spectrum and gas single spectrum to be detected.
Its ratio relation is as follows:
| H2 | C2H2 | C2H4 | CH4 | C2H6 | CO | CO2 | H2O | |
| Minimum measured value ( ppm ) | 10 | 1 | 3 | 1 | 20 | 5 | 10 | 5% |
| Repeatable accuracy ( +/-ppm ) | 5 | 0.3 | 0.6 | 0.2 | 5 | 2 | 5 | 3% |
| Measurement scope (ppm) | 10-2000 | 1-1000 | 3-1500 | 1-1500 | 20-1500 | 5-2000 | 10-8000 | 5-95% |
From above-mentioned table, (1) total hydrocarbon is higher, but when acetylene (C2H2) mass fraction is less than 5 ‰, can sentence and know typically thermal property fault.
(2) when total hydrocarbon height, acetylene (C2H2) mass fraction are more than 5 ‰, but the main component of acetylene not total hydrocarbon, the mass fraction of hydrogen (H2) is higher, can sentence and know for serious Superheated steam drier.
(3) total hydrocarbon is the highest, and when the mass fraction of hydrogen (H2) is not more than 100 ‰, methane (CH4) accounts for the main component in total hydrocarbon, can sentence and know partial discharges fault.
(4) total hydrocarbon is the highest, and when the mass fraction of acetylene (C2H2) is more than 100 ‰, the mass fraction of hydrogen (H2) is higher, can sentence and know spark discharge fault.
(5) total hydrocarbon is high, and the mass fraction height of acetylene (C2H2) and the main component of composition total hydrocarbon, the mass fraction of hydrogen (H2) is the highest, can sentence and know Arcing fault.
(6) when the mass fraction of hydrogen (H2) increases, other gas component does not increases, it may be that owing to equipment is intake or has bubble to cause water and iron
Chemical reaction or under high electric field action, water or the decomposition of gas molecule or corona effect and produce.(7) when fault relates to fixed insulation, carbon monoxide (CO), the carbon dioxide (CO2) content in oil can rise appreciably, typically no obvious boundary, for open type transformer, the mass fraction of carbon monoxide is typically below 300 ‰.When carbon monoxide exceeds 300 ‰ as total hydrocarbon is super, it is considered as the possibility that solid insulation is overheated.
(8) total hydrocarbon is high, keeps homeostasis through repeated detection, be ooze owing to the band oil of fuel tank or radiator welds benefit, overload, voltage tap switch unsceptered, on-load voltage regulation etc. and cause caused by equipment local or oil overheating.
Method as above, in described step 1), insulating oil is placed in Dewar bottle under vacuum, and heats the gas to be detected in Dewar bottle, and keeps constant temperature 30 °～45 °.
Method as above, described gas to be detected keeps constant temperature 35 °.
The technical scheme provided the embodiment of the present invention above is described in detail, principle and the embodiment of the embodiment of the present invention are set forth by specific embodiment used herein, and the explanation of above example is only applicable to help to understand the principle of the embodiment of the present invention；Simultaneously for one of ordinary skill in the art, according to the embodiment of the present invention, all will change in detailed description of the invention and range of application, in sum, this specification content should not be construed as limitation of the present invention.
Claims (6)
1. a method for oil-filled electric equipment diagnosis, is characterized in that comprising the steps:
The step 1) insulating oil to extracting from operating oil-filled electric equipment uses the operation that infrared spectrum analysis system is measured；
Step 2) gas to be measured is placed in michelson interferometer optical path, will obtain the interference wave that intensity is continually changing during mobile index glass on detector；Obtain gas interference pattern to be detected；
Step 3) background interference figure and gas interference pattern to be detected are fourier transformed；Obtain background single spectrum and gas single spectrum to be detected, thus obtain gas transmitted spectrum to be detected；
Step 4) obtains background single spectrum and the ratio relation of gas single spectrum to be detected according to the result in step 3).
Method the most according to claim 1, is characterized in that in described step 4), the ratio relation of background single spectrum and gas single spectrum to be detected obtains according to gas transmitted spectrum to be detected.
Method the most according to claim 1, it is characterized in that described step 2) mid-infrared light analysis of spectrum system is made up of data acquisition processing system, detector, Dewar bottle, beam splitter, horizontal glass, light source, index glass, described Dewar bottle connects detector, and detector connects data acquisition processing system.
Method the most according to claim 2, is characterized in that the ratio relation according to background single spectrum and gas single spectrum to be detected draws the content transformed value of each gas, thus judges fault and the fault type of oil-filled electric equipment.
Method the most according to claim 1, is characterized in that in described step 1), insulating oil is placed in Dewar bottle under vacuum, and heats the gas to be detected in Dewar bottle, and keeps constant temperature 30 °～45 °.
Method the most according to claim 5, is characterized in that described gas to be detected keeps constant temperature 35 °.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610181130.9A CN105866055A (en) | 2016-03-28 | 2016-03-28 | Method for diagnosing oil-filled electrical equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610181130.9A CN105866055A (en) | 2016-03-28 | 2016-03-28 | Method for diagnosing oil-filled electrical equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN105866055A true CN105866055A (en) | 2016-08-17 |
Family
ID=56625002
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201610181130.9A Pending CN105866055A (en) | 2016-03-28 | 2016-03-28 | Method for diagnosing oil-filled electrical equipment |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN105866055A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110411971A (en) * | 2019-08-08 | 2019-11-05 | 大连世有电力科技有限公司 | A kind of on-Line Monitor Device of methane and non-methane total hydrocarbons content |
| CN113075152A (en) * | 2021-03-26 | 2021-07-06 | 云南电网有限责任公司电力科学研究院 | Infrared light enhancement system for detecting content of dissolved gas in transformer oil |
| CN114894943A (en) * | 2022-03-21 | 2022-08-12 | 南京智鹤电子科技有限公司 | Transformer oil gas online monitoring method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103411920A (en) * | 2013-07-03 | 2013-11-27 | 安徽建筑大学 | Portable multi-component online monitor of gas dissolved in transformer oil |
| CN104237153A (en) * | 2013-06-07 | 2014-12-24 | 恒能华工监测技术(北京)有限公司 | Online rapid detection system for gas content of transformer oil |
| CN104914066A (en) * | 2015-05-04 | 2015-09-16 | 华北电力大学 | Detection device of dissolved gases in transformer oil based on infrared spectrum absorption |
-
2016
- 2016-03-28 CN CN201610181130.9A patent/CN105866055A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104237153A (en) * | 2013-06-07 | 2014-12-24 | 恒能华工监测技术(北京)有限公司 | Online rapid detection system for gas content of transformer oil |
| CN103411920A (en) * | 2013-07-03 | 2013-11-27 | 安徽建筑大学 | Portable multi-component online monitor of gas dissolved in transformer oil |
| CN104914066A (en) * | 2015-05-04 | 2015-09-16 | 华北电力大学 | Detection device of dissolved gases in transformer oil based on infrared spectrum absorption |
Non-Patent Citations (2)
| Title |
|---|
| 刘先勇 等: "用傅里叶红外变换实现在线溶解气体分析的研究", 《变压器》 * |
| 李红雷等: "用于变压器在线监测的傅里叶红外定量分析", 《电力系统自动化》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110411971A (en) * | 2019-08-08 | 2019-11-05 | 大连世有电力科技有限公司 | A kind of on-Line Monitor Device of methane and non-methane total hydrocarbons content |
| CN110411971B (en) * | 2019-08-08 | 2021-11-23 | 大连世有电力科技有限公司 | On-line monitoring device for methane and non-methane total hydrocarbon content |
| CN113075152A (en) * | 2021-03-26 | 2021-07-06 | 云南电网有限责任公司电力科学研究院 | Infrared light enhancement system for detecting content of dissolved gas in transformer oil |
| CN114894943A (en) * | 2022-03-21 | 2022-08-12 | 南京智鹤电子科技有限公司 | Transformer oil gas online monitoring method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Jiang et al. | TDLAS-based detection of dissolved methane in power transformer oil and field application | |
| Gómez et al. | Dissolved gas analysis (DGA) of natural ester insulating fluids with different chemical compositions | |
| Degeratu et al. | Condition monitoring of transformer oil using thermal analysis and other techniques | |
| Kalathiripi et al. | Analysis of transformer oil degradation due to thermal stress using optical spectroscopic techniques | |
| CN107389809B (en) | FR3 vegetable insulating oil oil dissolved gas ostwald coefficient measuring method | |
| CN105866055A (en) | Method for diagnosing oil-filled electrical equipment | |
| CA3005371C (en) | Analyzing fault gas concentration in liquid | |
| Zhang et al. | Detection of decomposition products of C4F7N-CO2 gas mixture based on infrared spectroscopy | |
| Alshehawy et al. | Evaluating the impact of aging in field transformer oil using optical spectroscopy techniques | |
| Wang et al. | Research on infrared spectrum characteristics and detection technology of environmental-friendly insulating medium C5F10O | |
| Narang et al. | Fault detection techniques for transformer maintenance using Dissolved Gas analysis | |
| Hamid et al. | Dissolved gas analysis (DGA) of vegetable oils under electrical stress | |
| Alshehawy et al. | Condition assessment of aged transformer oil using optical spectroscopy techniques | |
| Palmer et al. | Effect of aging on the spectral response of transformer oil | |
| Gu et al. | Detection of methanol dissolved in transformer oil by laser Raman spectroscopy | |
| Chen et al. | A review on a novel method for aging evaluation of transformer insulating paper based on methanol | |
| Boudraa et al. | Study of spectral response of transformer oil under low electrical discharge and thermal stress | |
| Miao et al. | Application research of laser gas detection technology in the analysis of Sulphur hexafluoride | |
| Jiang et al. | Dissolved acetylene detection in power transformer oil based on near-infrared absorption spectrum method | |
| Weesmaa et al. | Study of stray gassing measurements by different methods | |
| Borges et al. | Evaluation of the use of near infrared spectroscopy (NIR) in on-line monitoring of power transformer insulation oil | |
| Yun et al. | Infrared absorption properties analysis of dissolved gases in transformer oil | |
| Thiviyanathan et al. | Detection of inhibitor content in transformer oil at wavelengths below 1000 nm | |
| Munajad et al. | Dissolved gas analysis (DGA) and fourier transform infra red (FTIR) spectroscopy of thermal-aged natural ester-paper composite | |
| Hussain et al. | Incipient fault diagnosis of power transformers using optical spectro-photometric technique |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20160817 |
|
| WD01 | Invention patent application deemed withdrawn after publication |