Long service life, maintenance-free operation. Sealed boxes along with the transformer cover bolts or welded structure coupling, oil and air cut off contact, not damp insulation, insulation aging greatly reduce speed and improve the service life. Compact design, low operating noise. Due to the introduction of new materials and new technology to reduce noise, no conservator height lower than similar products. In the normal lifetime without an oil change, to improve the safety and reliability of the network operation. Corrugated tank is small, beautiful appearance. S11-type power transformer tank using corrugated sheet cooling, when the oil temperature, changes in the volume of oil by the elastic expansion corrugated sheets shrink to adjust compensation. Hanging core and oil-free testing. Transformer package, using vacuum filtration oiling process to completely remove the moisture in the transformer oil. After sealing the inside of the transformer is not in contact with the air, effectively prevent oxygen and moisture into the insulation performance degradation caused by a transformer.