Research on Lead Insulation Structure of 750kV Auto-transformer

The insulation structure of transformer leads should not only meet the requirements of temperature rise and reliable mechanical strength during long full load operation, but also withstand various Insulation Withstanding Test. Therefore, the insulation structure design of power transformer leads is one of the important technical problems in the insulation structure design of EHV power transformer. In order to design the insulation of a lead connection, it is necessary to determine the required insulation distance and insulation structure between the leads and the ground components according to the electric field calculation. This paper introduce the lead insulation structure of a 750kV single-phase auto-transformer, calculate the electric field of the 750kV leads by the finite element electromagnetic field simulation software. In this paper, the insulation structure of the high voltage and medium voltage leads of the transformer is calculated in detail, it shows that reasonable shielding measures and separated the oil gap can effectively reduce the field strength of the leads, and it increase the insulation strength and reliability of the leads, and provide guidance for the insulation structure design of EHV power transformer.