TITLE: Effects of Invertors on Rotating Machine Insulation Systems
ABSTRACT: Voltage source inverters (VSI) are now widely employed by utilities and industry to control the speed/power of motors rated up to 80 MW and to control the AC frequency of wind turbine generators. Applications include industrial motor speed control, electric vehicles, aircraft (both for adjusting flight control surfaces and as well for lifting/propulsion in small all-electric aircraft). Unfortunately VSI produce voltage impulses of relatively high magnitude, with risetimes as short as 20 ns. Such impulses can accelerate the aging of electrical insulation in rotor and stator windings. This presentation will overview low and high voltage VSIs and the impulses they create, identify the ways such pulses can age winding insulation in different environments, and outline how industry has addressed this problem.