Rieter

The motor

Index

Three-phase squirrel-cage induction motors are still used in ring spinning mills. They are cheap, require little maintenance, and are wear-resistant and uncomplicated. One disadvantage is their inflexibility, i.e. only one speed is available. This has compelled machinery manufacturers to provide supplementary devices for varying the speed. One such device could, for example, be a star-delta control. While the machine normally operates on delta at full speed, the motor can be switched to star during start-up, thus reducing power output to 1/3, with the speed being reduced according to the load. However, this also usually still results in increased ends down frequency.