Insulation systems available for PWM inverter fed motors for low voltage pulp and paper applications

This paper focuses specifically on integral horsepower AC induction motors used in the pulp and paper industry. An analysis of the various winding stresses is presented. The different requirements for the two insulation systems are discussed (MG1-Parts 30 and 31 for General Purpose and Definite Purpose Inverter Fed Motors), and test results show the need for higher dielectric insulations when the voltage levels of Part 30 are exceeded. The differences between existing, rebuilt and new motors is also explored. To assist the reader with additional research an extensive reference section is provided.