Using ac VSDs with squirrel cage induction motors

The use of ac Variable Speed Drives (VSDs) in conjunction with squirrel cage induction motors offers added benefits in terms of the start-up, control and running of mill applications within the mining industry. The VSD is able to control and limit starting current, torque, number of starts as well as acceleration during start with minimal limitations. Although the initial capital outlay might be higher for a VSD and Squirrel cage motor combination, the long term benefits in terms of reliability, flexibility of process control and the overall maintenance cost associated with the VSD combination, in comparison with liquid resistance starters (LRS) and wound rotor motor combination, will be a definite benefit.


Take note

  • Ac VSDs used with squirrel cage induction motors require a high initial capital outlay.
  • This combination is reliable, offers flexibility of process control and ensures lower maintenance costs.
  • The ac VSD and squirrel cage induction motor offers controlled start-up, running, torque and current draw.


Published as: Medium Voltage VSDs in mill drive applications

By C Watkins, Zest Electric Motors, Electricity+Control, November 2011 (pgs 40 – 43)