On the basis of the S9 series, the S11 series products have an average no-load loss of 20%. The no-load current is 70-85% lower than the S9. The temperature rise is reduced by 10K, and the service life is more than doubled. Even under the load of 20%. it can still be used for a long time. The running noise is reduced by 2-4 decibels. High and low voltage windings, body assembly, fuel tank structure, protection device, etc. are similar to S9 series transformers. It also adopts non-suspension structure, adopts vacuum drying, vacuum oil filtering and oil filling process, adopts corrugated oil tank, and has no oil storage cabinet and other structures.