Replacement of Ring Motors by Standard Motors Driven by Frequency Inverters in Hoisting Devices

Resumen

This work has the purpose to discuss in a summarized way the aspects innate at the functioning of three-phase induction motors emphasizing those that affect their energy efficiency in hoisting devices. Following this, present the techniques used in induction motors driving, applied to lifting equipments, that is, overhead cranes. A comparative between the technologies used and still in use with the modern electronic drives currently used will be presented. It intends show too, in a real way, the benefits, gains and evolutions acquired after the refurbishment of an Overhead Crane with 650/30 tons of lifting capacity. These overhead cranes drove before by slip ring motors and velocity control through of variation at the value of extra rotor resistance, held electromechanically, was completely substituted by a technology based on squirrel cage rotor motors (standard) and speed variation through of variable frequency drives