Optimization of the stress grading layers on the slot exit on stator coils used in high voltage rotating machines with help of FEM model and the comparison to the analytic calculation

The intention of this report is to introduce an option of optimal design of end corona protection - ECP within slot exit of stator bar of high voltage rotating machines. The proposal is realized due to examination of electric potential on semi-conductive coating by means of analytical calculation issued from telegraph equations and this one is compared with calculation outgoing from FEM model. The FEM model is created in the environment of software ANSYS/MAXWELL. Both analytical and FEM model can be configured for a single stage and/or double stage ECP arrangement.