Stress-strain analysis and safety check during arc discharge in UHV transformers

Abstract

Arc discharge caused by short-circuit faults is one of the most serious faults in UHV transformers， with the potential for inducing deformation， rupture， burning， or even explosion of the oil tank. In order to analyze the stress-strain levels induced by arc discharge in transformers， a finite element model for a 1，000 kV single-phase UHV transformer was established. The simulation and analysis focused on the pressure distribution within the oil tank caused by arc discharge at different locations and energy levels. Stress-strain levels in both the oil tank and bolts were calculated， with a comprehensive safety check on their mechanical properties based on material parameters. Additionally， the discharge energy thresholds leading to tank wall rupture or bolt damage were determined. The findings reveal that the maximum stress during arc discharge near the high-voltage winding in the oil tank is located at the corner of the tank wall， and the maximum deformation is observed in the middle of the tank wall along the long axis. Furthermore， the maximum stress during arc discharge inside the lifting seat is concentrated at the support of the elevated seat， with the maximum deformation observed at the turning point of the elevated seat.

Keywords

• uhv transformer
• arc discharge
• oil tank
• bolt
• stress
• strain
• safety check