Applications for secure isolation transformer, isolation, leakage current, clean power, eliminating the third harmonic and suppress common mode interference occasions. Suitable for AC 50Hz to 400Hz, the following circuit voltage of 1000V, widely used in lighting, electrical machines, machinery and electronic equipment, medical equipment, such as an isolation transformer rectifier unit is divided into two categories according to use purposes; one is to prevent accidents and electrocution for the safety of the power supply transformer isolation. Another type of isolation transformer is an electromagnetic interference signal isolation, it is widely used in electronic circuits, suppressing noise and electromagnetic interference.