{"id":877,"date":"2014-05-06T20:08:38","date_gmt":"2014-05-06T18:08:38","guid":{"rendered":"http:\/\/globecoreoil.com\/?p=877"},"modified":"2014-05-06T20:08:38","modified_gmt":"2014-05-06T18:08:38","slug":"quality-assurance-methods-of-transformer-oil-testing","status":"publish","type":"post","link":"https:\/\/aceite.globecore.com\/quality-assurance-methods-of-transformer-oil-testing","title":{"rendered":"Quality Assurance: Methods of Transformer Oil Testing"},"content":{"rendered":"

The performance characteristics of transformer insulating oil are monitored and tested at several stages during its service life.\u00a0 Regular monitoring of the oil\u2019s quality and condition is a part of the process of servicing electric power equipment. The condition of the oil, its purity and contamination level will greatly help in indicating the condition of the transformer’s solid insulation.\u00a0 It is therefore, essential to the life of the transformer to periodically monitor the condition of the insulating oil.\u00a0 The heart of the transformer is the solid insulation, but the insulating oil is the life blood of the transformer.\u00a0 Without the life blood, the heart will die.
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The ability of insulating oil to maintain its original performance characteristics during long term operation of electric equipment is referred to as “oil stability.”<\/em>\u00a0 If the electric power equipment has no defects and operates in accordance with design and expectations, the performance characteristics of new oil will change and degrade slower.\u00a0 When new, transformer oil has a very light color and complies with performance standards that include dielectric strength and other important characteristics.\u00a0 During the course of the oil’s service life, the stability of the oil decreases and visible changes occur and oil’s color slowly becomes darker and darker.<\/p>\n

Contaminated oil usually has a high ash content, increased acidity and presence of low molecular acids.\u00a0 Acidic sludge forms in contaminated oil and aggressively attacks the cellulose insulation and reacts with the metals of the transformer\u2019s other internal components.<\/p>\n

Timely oil monitoring and oil analysis programs can identify when the oil needs to be changed or serviced through an oil purification and\/or oil regeneration process.\u00a0 Servicing the oil before it becomes aggressive against the solid insulation is the key to extending the service life of your transformers.<\/p>\n

The main physical and chemical properties tested are the oil\u2019s dielectric strength, dissipation factor, flashpoint, color, amount of solid particulate matter, water content, gas content and the oil’s acid number.<\/p>\n

Dielectric strength is one of the most important indications of oil stability and this is often the first test performed.\u00a0 The “dielectric breakdown test”<\/em> is calculated as an average of five breakthroughs achieved in a standard discharger with two electrodes submersed in the oil at 2.5 mm distance from each other.\u00a0 Six breakthroughs are achieved in the test and the last five are averaged.\u00a0 If the oil is fresh, the lowest allowable breakthrough voltage is 30 kV.\u00a0 In some transformers, that meets the minimum operating standard.<\/p>\n

Decreasing dielectric strength is caused by contamination of the oil by gas, moisture, cellulose fibers or other particulate matter.<\/p>\n

A similar process is used to calculate the oil’s “dissipation factor.”\u00a0 It is the the oil\u2019s ability to neutralize energy, prevent breakthroughs and cool the transformer. \u00a0 It is a characteristic of the oil\u2019s quality and purity and acidity.\u00a0 In general, an increased dissipation factor means degradation of the oil\u2019s dielectric capabilities.<\/p>\n

The color of transformer oil changes from light yellow to cloudy brown under the influence of temperature, contaminants and electric current.\u00a0 The color is not in itself an indication of any specific problem, but a dark color is usually an indication of aged and\/or contaminated oil.<\/p>\n

The presence of solid particles in the oil and the acid number of the oil are two related oil purity characteristics.\u00a0 Unsolved materials accumulated in the oil in the form of sludge or suspended particles (fibers, dust, solved paint, metal particles, ash etc) degrade the oil\u2019s dielectric properties and promote oil oxidation.\u00a0 The more particles that are present in the oil, the faster the oil ages. The acid number is expressed as milligrams of KOH required to neutralize all acids in a gram of oil and indicates the degree of oil aging.\u00a0 A normal and acceptable acid number is 0.25 mg KOH\/g, while the limit of contaminant content is 515 parts per million (ppm).<\/p>\n

Moisture and gas content in transformer oil must be tested for thoroughly.\u00a0 Water and gases are very damaging to your transformer insulation system and are two main cause of the oxidation process and oil aging process.<\/p>\n

Moisture and water content is measured as amount of hydrogen when reacting the oil with calcium hydride in a certain period of time.\u00a0 Gas content is measured by an absorptiometric analyzer or a chromatographer.<\/p>\n

The oil’s flashpoint and the oil’s setting point are two indications of the general fire safety of the oil and the oil’s ability to operate in adverse temperature conditions both hot and cold.<\/p>\n

The are distinct advantages of testing and analyzing transformer oil before starting your electric power equipment and during scheduled maintenance events.\u00a0 Oil testing allows the operator to determine the equipment\u2019s operating efficiency, conditions and the possibility of future malfunctions.\u00a0 If the purity and quality standards are followed, the equipment will be less likely to experience failures and downtime and unscheduled maintenance and repair costs.<\/p>\n","protected":false},"excerpt":{"rendered":"

The performance characteristics of transformer insulating oil are monitored and tested at several stages during its service life.\u00a0 Regular monitoring of the oil\u2019s quality and condition is a part of the process of servicing electric power equipment. The condition of the oil, its purity and contamination level will greatly help in indicating the condition ofRead More <\/a><\/p>\n","protected":false},"author":24,"featured_media":887,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[20,28,16,8],"class_list":["post-877","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tierra-fuller","tag-oil-filtration","tag-oil-reclamation","tag-oil-testing","tag-transformer-oil"],"acf":[],"language":"en","_links":{"self":[{"href":"https:\/\/aceite.globecore.com\/en\/wp-json\/wp\/v2\/posts\/877","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aceite.globecore.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/aceite.globecore.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/aceite.globecore.com\/en\/wp-json\/wp\/v2\/users\/24"}],"replies":[{"embeddable":true,"href":"https:\/\/aceite.globecore.com\/en\/wp-json\/wp\/v2\/comments?post=877"}],"version-history":[{"count":0,"href":"https:\/\/aceite.globecore.com\/en\/wp-json\/wp\/v2\/posts\/877\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/aceite.globecore.com\/en\/wp-json\/"}],"wp:attachment":[{"href":"https:\/\/aceite.globecore.com\/en\/wp-json\/wp\/v2\/media?parent=877"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/aceite.globecore.com\/en\/wp-json\/wp\/v2\/categories?post=877"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/aceite.globecore.com\/en\/wp-json\/wp\/v2\/tags?post=877"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}