ABSTRACT Dry‐type distribution transformers are widely used in indoor power supply systems on the user side, where their short‐circuit withstand capability is critical for operational reliability. To enhance this capability, this study established field‐circuit coupled and magnetic‐structural coupled simulation models with identical structural dimensions. Taking an SCB‐630 kVA/10 kV transformer as an example, single‐phase‐to‐ground, two‐phase‐to‐ground, and three‐phase short‐circuit faults were simulated to analyse winding current and magnetic field distributions. The Lorentz force under three‐phase fault conditions were calculated, and winding deformation was compared with and without axial constraints at the upper end. The results show that: approximately 85.71% of unqualified transformers failed due to excessive partial discharge during short‐circuit withstand tests; the short‐circuit current increased by about 30 times compared to the rated load, with the magnetic flux density rising by up to 50 times to 0.36 T under all three short‐circuit types; the maximum radial and axial forces on the low‐voltage winding reached 3.64 × 10 6 N/m 3 and 8.20 × 10 5 N/m 3 , respectively; with axial constraints applied, the maximum displacement was 5.49 × 10 − 5 mm. This result provides quantitative data for understanding the damage cause of a dry type transformer under short circuit.A statistical analysis was carried out on 57 sampled 10 kV dry‐type transformers with short‐circuit test data from a testing centre. Taking the SCB‐630 kVA/10 kV model transformer as a simulation type, we established a field‐circuit coupling model and a magnetic‐structure coupling model with the same structural dimensions.
Huang et al. (Thu,) studied this question.