In today\u2019s modern electric power industry, transformer oil sampling and analysis has begun to enjoy wide popularity. \u00a0A good oil analysis program provides equipment owners the ability to determine the current condition of a transformer and schedule prevetive maintenance so as to avoid possible failures in future. In addition, the assessment of the transformer\u2019s potential service life requires performing a dissolved gas analysis of the dielectric insulating oil in order to have a complete picture of the health of the transformer.<\/p>\n
The aging of dielectric insulating materials and other parts inside a transformer leads to the creation of harmful and unwanted gases. A thorough analysis of these gases that are generated in a transformer is a necessary tool in performing a comprehensive preventive maintenance service on the transformer.<\/p>\n
Generally speaking, there are a lot of methods available to analyze the content of gases in oil, but a dissolved gas analysis<\/b> is preferred since only a dissolved gas analysis can provide the truest and most accurate results. \u00a0This analysis process consists of sampling and analyzing the oil to determine the kind and amount of gases in the oil.<\/p>\n
According to ASTM D3613, ASTM D3612, and ANSI\/IEEE C57.104 standards, a dissolved gas analysis of transformer oil should be performed every year so that year to year results can be compared and so that problems can be identified early.<\/p>\n
This article considers the possible ways of interpreting the results of the annual analysis. \u00a0Electrical perturbations and thermal destruction will cause the creation of gases in transformers. \u00a0It is also important to remember that some gases are formed in a transformer even at normal operating temperatures and under normal conditions. \u00a0It is therefore, important to perform a dissolved gas analysis annually.<\/p>\n
The composition of dielectric insulating oil contains hydrocarbon molecules that break down into carbon-hydrogen and carbon-carbon compounds when subjected to thermal and electric failures. \u00a0The breakdown process generates atoms of hydrogen and hydrocarbon fragments that create unwanted gases. \u00a0Additionally, the slow degradation process of cellulose insulation results in the production of such gases as methane, hydrogen, and carbon monoxide. \u00a0It is temperature and the amount of material that determine the speed of gas formation. \u00a0A larger amount of cellulose insulation at normal temperatures will produce the same amount of gases as a smaller amount of insulation at higher or more extreme temperatures. \u00a0That is why it is essential to check the content of dissolved gases in oil regularly.<\/p>\n
After a thorough analysis of the samples taken, one should determine the level of each unwanted gas found in the oil. \u00a0Large deviations from the normal\/accapatable values of gas concentration in the oil can indicate potential future failures in the transformer\u2019s operation. \u00a0The table below shows the recognized values for gas concentration provided by ANSI\/IEEE C57.104.<\/p>\n
| \n Gas description<\/strong><\/p>\n<\/td>\n Key gas concentration (in ppm)<\/strong><\/p>\n<\/td>\n<\/tr>\n Normal limits (<)<\/strong><\/p>\n<\/td>\n Action limits (>)<\/strong><\/p>\n<\/td>\n Potential fault type<\/strong><\/p>\n<\/td>\n<\/tr>\n hydrogen<\/p>\n methane<\/p>\n acetylene<\/p>\n ethylene<\/p>\n ethane<\/p>\n carbon monoxide<\/p>\n carbon dioxide<\/p>\n Total combustibles<\/p>\n<\/td>\n H2<\/p>\n CH4<\/p>\n C2H2<\/p>\n C2H4<\/p>\n C2H6<\/p>\n CO<\/p>\n CO2<\/p>\n TDCG<\/p>\n<\/td>\n 150<\/p>\n 25<\/p>\n 15<\/p>\n 20<\/p>\n 10<\/p>\n 500<\/p>\n 10,000<\/p>\n 720<\/p>\n<\/td>\n 1,000<\/p>\n 80<\/p>\n 70<\/p>\n 150<\/p>\n 35<\/p>\n 1,000<\/p>\n 15,000<\/p>\n 4,630<\/p>\n<\/td>\n Corona, arcing<\/p>\n Sparking<\/p>\n Arcing<\/p>\n Severe overheating<\/p>\n Local overheating<\/p>\n Severe overheating<\/p>\n Severe overheating<\/p>\n<\/td>\n<\/tr>\n If the results of dissolved gas analysis show that the amount of gas has increased, it is recommended to carry out additional testing to confirm the obtained results and to determine if the values are still increasing. \u00a0If after rechecking, the results still show that the values are above the acceptabe limits, a transformer should be subjected to a thorough offline inspection.<\/p>\n If the gas concentration in the oil has increased, other methods such as Duval\u2019s Triangle Model, Doernenburg ratios and Rogers ratios should be applied to evaluate the potential problems in the transformer\u2019s operation.<\/p>\n Taking everything into consideration, we should say that dissolved gas analysis of transformer oil makes it possible to predict and prevent the possible breakdown of equipment. \u00a0If there has been a \u00a0sharp increase of unwanted gas concentration in the oil, it is desirable to use diagnostic techniques to detect the nature and cause of the possible problems.<\/p>\n In conclusion, we have determined that the majority of transformer breakdowns are caused by the degradation of the oil\u2019s performance characteristics. \u00a0With this in mind, GlobeCore\u2019s<\/i><\/b> engineering department has developed the CMM line of units that are designed to de-gas and purify transformer oils by removing particulate matter, water, moisture, gases and other contaminants. \u00a0GlobeCore\u2019s<\/i><\/b> equipment has enjoyed wide acceptance and excellent results in more than 70 countries around the world.<\/p>\n","protected":false},"excerpt":{"rendered":" In today\u2019s modern electric power industry, transformer oil sampling and analysis has begun to enjoy wide popularity. \u00a0A good oil analysis program provides equipment owners the ability to determine the current condition of a transformer and schedule prevetive maintenance so as to avoid possible failures in future. In addition, the assessment of the transformer\u2019s potentialRead More <\/a><\/p>\n","protected":false},"author":7,"featured_media":2552,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[198,197,38],"class_list":["post-2551","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-case_studies","tag-analysis","tag-dissolved-gas","tag-transformer-oil"],"acf":[],"language":"en","_links":{"self":[{"href":"https:\/\/oilregeneration.globecore.com\/en\/wp-json\/wp\/v2\/posts\/2551","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/oilregeneration.globecore.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/oilregeneration.globecore.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/oilregeneration.globecore.com\/en\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/oilregeneration.globecore.com\/en\/wp-json\/wp\/v2\/comments?post=2551"}],"version-history":[{"count":0,"href":"https:\/\/oilregeneration.globecore.com\/en\/wp-json\/wp\/v2\/posts\/2551\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/oilregeneration.globecore.com\/en\/wp-json\/wp\/v2\/media\/2552"}],"wp:attachment":[{"href":"https:\/\/oilregeneration.globecore.com\/en\/wp-json\/wp\/v2\/media?parent=2551"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/oilregeneration.globecore.com\/en\/wp-json\/wp\/v2\/categories?post=2551"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/oilregeneration.globecore.com\/en\/wp-json\/wp\/v2\/tags?post=2551"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}} |