Rotary machine diagnostic system

A rotary machine system comprising:

• a power supply that supplies three-phase alternating current power;
• an electric motor that receives the three-phase alternating current power from the power supply;
• power supply lines interconnecting the power supply and the electric motor;
• a diagnostic system including a current sensor that measures current of the power supply lines and outputs current measurement data, voltage sensors that detect respective electric potentials of the power supply lines and output voltage measurement data, and a data processing apparatus that receives the current measurement data and the voltage measurement data and performs transient response analysis on a predetermined equivalent circuit model, which is equivalent to a leakage current path of the electric motor, using the current measurement data and the voltage measurement data that are respectively measured at predetermined time intervals having a predetermined time width by the current sensor and the voltage sensors, and extracts parameters of the leakage current path equivalent circuit model.