Many industrial processes require variable speed load drive devices, such as pumps for varying liquid flow; fans for variation of air flow; transport systems to vary the transport speed; lathes for variation of cutting speed; winding machines to compensate for the variation of the coil diameter.
For a long time, variable speed industrial applications have been dictated by process requirements and limited by technology because of cost, efficiency and maintenance requirements and components employed. https://www.mrosupply.com/couplings-collars/elastomer-couplings/5002443_017129_dodge/ In the past, the speed variation was made by a fixed speed induction motor and was the first electric energy conversion device for mechanical energy, energy conversion device through mechanical, hydraulic or electromagnetic components (according to the energy conversion device .
A motor starting device joins all the components necessary to control and protect an electric motor and the selection of the components to constitute a device conditions the performance of the installation. The main components required are: protection level, fixed or variable speed operation, sectioning, protection against short circuits, protection against overload and switching.