Slip-Ring Motor Starters are part of the series of resistors applied to rotor circuits in order to control the speed/torque characteristics of a motor.
Rotor starters are mainly used for motor startup applications requiring high-starting torque, such as loaded belt conveyors in the mining industry. By using external resistors, it is possible to shift the motor’s maximum (break-down) torque up to the starting torque point for motors under heavy loads during start-up. The resistors are split into steps and controlled via contactors by a motor startup control system. As the motor speed increases, the external rotor resistors are eliminated by shorting contactors until all external resistors have been shorted out.
Slip-ring motor starters are made in two types: dry- or oil-immersed.
- Crane systems
- Mill application