A special liquid resistor is connected in series to the rotor circuit of slip ring motor; the liquid resistor get to work when the motor starts and its resistance gradually decrease during the preset time, so as the motor can start smoothly and accelerate eventually at minimal rated current and maximum torque. After start process is completed, the rotor circuit is shorted by the contactor. Its low starting current results in no impact on motors, load and power system as well as in no harmonic to affect the power system.

No maintenance is needed for the starters as automatic water filling system controlled by electrolyte level sensor and PLC can automatically fill the electrolyte tank with required amount of water when necessary.(optional)