The S11 oil-immersed transformer is a new-generation transformer developed in recent years, featuring low noise and low loss. Its iron core is seamless, significantly reducing no-load losses and current, cutting the no-load current by 60% to 80%. The high and low voltage windings are continuously wound on the core column, with tight winding and good coaxiality, enhancing the product's anti-theft characteristics. Noise reduction exceeds 10 decibels. Temperature drop is 16-20K. Due to the continuous winding of the iron core (with a pure circular cross-section), the orientation of silicon steel sheets is fully utilized, reducing no-load losses by 20% to 30%.