| Abstract [eng] |
Each dielectric situated in electromagnetic field polarizes. When through it flows electric current, which dissipates a certain amount of electric power. This power turns into thermal energy. In other words, during the period of polarization, there is a certain amount of electric power, which is throwed away in dielectric. Normally this kind of losses in dielectric material is directly proportional to voltage. During the period of operation, transformers collide with many harmful factors such as high temperature, vibration, electric field as well as appearance of moisture, oxygen, acids and other chemicals. These factors gradually reduce properties of isolation. Since moisture always is especially harmful bi-product, so that assesment of its amount is beneficial aging indicator. Isolation could be determined as dielectric model. With increasing amont of moisture, it causes corresponding changes. Comparing performed measurements results with model curves, there could be assesed major isolation parameters such as amount of moisture in paper and oil conductivity. In order to determine overall dielectric condition and its losses, there is selected transformer of High Voltage Laboratory of Kaunas University of Technology. The research is performed with OMICRON DIRANA test set, which operating is based on frequency domain spectroscopy with FDS and PDC methods. |
