Stress Analysis And Sealing Performance Research Of Large Transformer Main Sealing Surface

In order to prevent the leakage of the insulating material inside the transformer and the intrusion of media such as air,a variety of seals are required to ensure the normal operation of the equipment during the transformer operation.With the development of transformers towards the direction of ultrahigh voltage,ultra-long-distance transmission,and large loads,seals not only need to withstand higher pre-tightening forces,but also need to protect the transformer from generating under various effects such as temperature changes,ultraviolet rays,and magnetic excitation vibration.In order to achieve this goal,higher requirements are imposed on seal materials,mechanical behavior and wear resistance.At this stage,people mainly focus on the finite element analysis of the contact stress and VonMises stress of the flange bolt system,and have obtained many research results.However,few people have established a suitable flange bolting system for the working conditions of the transformer and performed a finite element analysis on the working conditions of the transformer.The temperature change of the rubber gasket during the sealing process will affect the sealing effect of the transformer.In the process of temperature and stress analysis of the flange bolt system,people usually perform conventional thermal coupling.Few people carry out finite element analysis of the temperature change of the transformer affected by the environment.To this end,this paper uses the finite element analysis method to model the main sealing interface of the oil-immersed transformer—bolts,gaskets,and flange systems,and analyzes the stress and deformation of the flange bolts in the pre-tightened state,Explore the change of contact stress with compression rate,fluid pressure,and hardness.Analyze whether the contact stress generated between the sealing gasket and the rigid body meets the requirements of the seal when different loads are applied to the bolt,that is,the contact stress is greater than or equal to the fluid pressure.The simulation results and the test results match well,which further proves the reliability of the finite element analysis method.The numerical simulation method is used to analyze the steady-state temperature field and coupling field of the bolt flange system.Based on this,the stress distribution of gaskets and bolts at different media temperatures and the contact stress changes of gaskets under temperature changes were analyzed and compared.Through the research in this paper,the most vulnerable locations of the flange bolt system will be given,and the stress distribution of rubber gaskets under different hardness,temperature,compression rate,and fluid pressure conditions will be grasped.This thesis promotes the development of rubber seals for large transformers,and at the same time helps to extend the service life of rubber seals for large transformers.