Speed starters - connect, adjust and start: The new speed starter with particularly intuitive operation This compact solution offers all the necessary functions for different speeds, soft start and safe stopping thanks to Safe Torque Off (STO). Operating three-phase asynchronous motors safely, simply and efficiently is an important goal in many applications. The CONTACTRON speed starter offers simple operation at different speeds from normal speed, creep speed and soft start up to energy efficient mode and ramp function.