Analysis And Improvement On Breakdown For Dry Type Transformer

The dry-type transformers become more and more popular at present quickly-developing social economy, due to the advantages of no pollution and less maintenance. Since there is a big demand on the dry-type transformer, the issue to improve the voltage class and breakdown has to be highlighted by all the manufacturers who have been aware of the very important subject on how to avoid insulation breakdown during transformer running.In this thesis, the comprehensive analysis on insulation classification and characteristic and arcing classification are presented for the three most important part of dry type transformers: core, winding and leads. It also contains the insulation relationship and inner insulation structure with understanding that the air contributes the substantial for main insulation while epoxy resin for minor insulation. In order to find out the insulation defect, the insulation tests have to be carried out, such as Power Frequency withstand testing, induced voltage withstand testing and partial discharge testing. The insulation testing result can produce feedback to the calculation of insulation clearance between each parts based on Electric field strength requirements of transformer components and the adjustment of insulation clearance could help to reduce Electric field strength. It becomes practical to improve processing control and avoid burrs, bubbles and dehiscence in windings so that the insulation performance can be guaranteed.Analysis and efficient measurements on breakdown for dry type transformer are taken into consideration to reduce Electric field strength and improve the manufacturing process. The three insulation tests have been taken to produce the efficient measurement which could improve the insulation performance and guarantee the reliability of dry-type transformer running at practice.