Application Applied to wound-rotor asynchronous motor overloadsmoothly soft start are which three phase current380V,660V,3KV,6KV,12KV, power rating 45~10000KW. Working PrincipleThe controlled of wound-rotor asynchronous motor rotor loop inseries with the three-phase star connection liquid resistance,fluid resistance with starting motor and automatic input,resistance will be stepless reduced within predetermined time,close to zero automatic excision, thus motor access rated currentand maximum torque circumstances no impact on the smooth start-up.Perforamance and features 1.Low starting current and constantly, noimpact on the grid; 2. The starting current is less than 1.3 timesof rated current,it can reduce the capacity of transformers 3. Itcan start under low voltage, power grid voltage can ensure motorrun normally,then starting smoothly 4. It can start for 5~10 timesin succession 5. It smooth start up, little impact of mechanicalstress, can protect the motor and transmission machineryeffectively 6. Applicable to heavy load start 7. Simple structure,convenient installation and maintenance, high reliable WorkingVoltage 3AC380V~20kV±10%,50HZ Temperature 0-40°C Humidity <90%Absolute altitude ≤2000M certifiacte CCC