Research On Process Control Measures Of Partial Discharge In Oil-immersed Transformer

The oil-immersed transformer plays a prominent role in the power system at the present stage,and enough attention should be paid to the partial discharge during the manufacure of transformer,because the partial discharge is one of the most common reasons caused power transformer faults.The partial discharge measurement test should be done before the transformer leaves the factory and the value of the partial discharge should be controlled within a certain range to ensure its electric strength.ACLD test and ACSD test are done to measure the partial discharge according the different values of the maximum equipment voltage.According to the paractial tests of transformers,several oil-immersed transformer examples with partial discharge are selected in this paper from the reasons of defects in insulation and the foreign bodys.Their specific reasons are unevenness of insulation,bubble,improper drying of insulation,faults during vacuum oil filling,metal foreigh body,suspended metals and transformation of conductor.The test data are introduced,which cover the values of partial discharge,the ultrasonic results and the chromatographic dignals.The cases are introduced and analyzed from evenness of insulation,bubble,drying of insulation,requirements of vacuum oil filling,metal foreigh body,suspended metals and transformation of conductor.The positions and the reasons of these cases are analyzed and the repairing plans are stated.Tthe key points of the process controlling and the corresponding technical measures are stated.And the meaures include more and higher requirement about the pressboard manufacturing,drying the extra insulation by vapor phase drying,higher parameter requirement on vacuum oil filling,improving the transformation of conductor by using the semi-conductive paper rolling leads and so on.By taking the measures stated in this paper,the partial discharges are removed in these cases.