{"id":3882,"date":"2024-01-11T09:08:41","date_gmt":"2024-01-11T08:08:41","guid":{"rendered":"https:\/\/rd-coach.com\/?p=3882"},"modified":"2024-09-20T11:38:56","modified_gmt":"2024-09-20T09:38:56","slug":"result-analysis-of-a-discharge-test","status":"publish","type":"post","link":"https:\/\/rd-coach.com\/en\/result-analysis-of-a-discharge-test\/","title":{"rendered":"Result analysis of a discharge test"},"content":{"rendered":"\n

Initial situation<\/h3>\n\n

Two types of transformer bushings from my customer were subjected to a special test. It was checked how the bushings would behave in the event of a breakdown inside the insulator and whether the oil in the transformer could catch fire due to the short circuit.<\/p>\n\n

Both types failed the test. I was asked to use simulations to find out the reasons for the failure and to use the knowledge gained to work out improvements.<\/p>\n\n

Realisation<\/h3>\n\n

For the simulation of the fast processes during the internal breakdown in the bushing, I have chosen LS-Dyna – an explicit simulation method. I realised the energy deposited by the breakdown in the bushing with an ambient condition coupled with an equation of state of a gas. The idea behind this is that the insulation material in the plasma channel is in a gaseous state.<\/p>\n\n

The energy in the plasma channel is represented by the gas temperature. I calculated this with a complex model in LT-Spice, which shows the different temporal phases of the spark resistance in detail. As the processes take place quite quickly and therefore the temperature in the surrounding insulation material hardly rises, a very large temperature reservoir can be assumed. I have taken into account the heat conduction from the plasma to the reservoir with a constant layer thickness. This leads to a plasma temperature of several thousand Kelvin which, however, remains almost constant after the first quarter of the period. This is in agreement with observations in high-energy water breakdowns[1]<\/a>.<\/p>\n\n

I set the temperature curve over time as an input parameter in LS-Dyna for the equation of state. To save time and licence fees, not the entire bushing was modelled but only a section. While I used the Euler formalism for the plasma channel, the components of the bushing use the Lagrangian method. This required a lot of attention to the coupling between the two regimes.<\/p>\n\n

The simulation made it possible to roughly reproduce the observed failure behaviour. This allowed me to suggest measures that would minimise the probability of failure. In addition, I found test parameters within the given text conditions that should make a successful test more likely.<\/p>\n\n

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[1]<\/a> R. Zange – Application-related process model of the conversion of electrical energy into energy of the power sound impulse – Dissertation University of Magdeburg (2000)<\/p>\n\n

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Targets and key figures<\/h4>\n\n
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<\/path><\/svg><\/span>Plasma temperature calculated from test parameters<\/span><\/div>\n\n\n\n
<\/path><\/svg><\/span>LS-Dyna model of the implementation simulated<\/span><\/div>\n\n\n\n
<\/path><\/svg><\/span>Euler, Lagrangian method and their coupling created<\/span><\/div>\n\n\n\n
<\/path><\/svg><\/span>Improvement principle and optimized test parameters proposed<\/span><\/div>\n<\/div><\/div>\n<\/div>\n<\/div>\n\n
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August – September 2023<\/p>\n<\/div>\n<\/div>\n\n

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Budget 14’000 CHF<\/p>\n<\/div>\n<\/div>\n\n

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Independent project work<\/p>\n<\/div>\n<\/div>\n\n

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Energy technology<\/p>\n<\/div>\n<\/div>\n\n

Testimonial<\/h4>\n\n
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“Mr M\u00fcller-Siebert carried out this project with seriousness and interest. He worked very independently and searched for the necessary and missing information in the literature.Without the cooperation of Mr. M\u00fcller-Siebert, we would never have had these valuable results due to a lack of capacity and expertise. He delivered the results in a professional report.”<\/div>
Development Manager<\/span>Customer wants to remain anonymous<\/span><\/div><\/div><\/div><\/div><\/div><\/div><\/div>\n\n
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<\/a><\/path><\/svg><\/span>PDF<\/span><\/div>\n<\/div><\/div>\n\n\n\n
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<\/a><\/path><\/svg><\/span>Back<\/span><\/div>\n<\/div><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

Initial situation Two types of transformer bushings from my customer were subjected to a special test. It was checked how the bushings would behave in the event of a breakdown inside the insulator and whether the oil in the transformer could catch fire due to the short circuit. Both types failed the test. I was […]<\/p>\n","protected":false},"author":1,"featured_media":2236,"comment_status":"open","ping_status":"open","sticky":false,"template":"wp-custom-template-projekte","format":"standard","meta":{"_acf_changed":false,"_uag_custom_page_level_css":"","footnotes":""},"categories":[69,68],"tags":[],"class_list":["post-3882","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-highvoltage","category-productdeveloper"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t