Handling high torque starts in new and retrofit applications

Many applications have a higher starting torque requirement and it is sometimes a struggle to provide smooth starting performance. VFD starts are known to reduce starting stresses but may not always provide the best overall solution when economics, performance and process control are considered. This paper will review considerations for new and retrofit applications, touching on torques required by various loads, matching this with torque characteristics of direct on line (DOL), reduced voltage and VFD starting controllers. It will also cover aspects of tuning and control issues with the controllers mentioned to maximize torque performance and minimize commissioning issues with an induction motor (IM) starting.