Abstract:Three-phase induction machine of high power always uses Star-delta starting to reduce starting current. In theory, star-delta starting can reduce starting current and starting torque as low as Full-voltage starting. But testing shows that reduced multiple has a large gap between theory and practice. By starting test and finite-element analysis on three-phase induction machine of 4 poles 800 kW/6 kV, stator and rotor leakage reactance under full-voltage and star-delta are different in practice, which is constant in theoretical calculation. Detailed reduced multiple of starting current and starting torque are dependent on the degree of magnetic flux density saturation.