Design of ZnO microvaristor end corona protection for electrical machines

For the stator winding of electrical machines, end corona protection arrangements including semi-conductive microvaristor lacquers are analyzed using finite element method (FEM) simulations. Those materials feature nonlinear resistive properties depending on the local electric field. Hence, electroquasistatic FEM simulations considering capacitive and nonlinear resistive material behavior are performed. End corona protection arrangements using semi-conductive materials are compared. The resulting voltage distributions, tangential electric fields and ohmic losses are presented.