The 66kV series power transformer products are based on the combination of European advanced technology and the use of computer-aided design and advanced stacking technology in the design, which fully guarantees the roundness of the iron core in the design and production. During the suit, the inner winding cardboard cylinder and the iron core are equipped with a log brace at the opposite position of the inner winding brace, so that the inner winding cardboard cylinder and the iron core log brace are closely matched, providing a reliable fulcrum for the inner winding when bearing the short circuit impact, so that the short circuit force can be reliably transferred to the iron core, and ensuring that the inner winding does not deform when bearing the short circuit impact. The winding design makes the current and temperature uniformly distributed along the winding, and makes the winding obtain the best voltage distribution when it is used under full wave and chopped wave impact conditions. The winding can withstand short circuit, overload, and overvoltage without local overheating. The winding and lead are bound firmly enough to form a steel body to prevent relative displacement due to transportation, vibration and short circuit during operation. It has the characteristics of low noise, low partial discharge, low temperature rise, short circuit resistance, impact resistance, no leakage and beautiful appearance. The performance of the transformer conforms to European energy efficiency standards and Chinese energy efficiency standards.