AC modeling and anisotropic dielectric properties of stress grading of form-wound motor coils

The paper addresses the ac modeling and anisotropic dielectric properties of stress grading and conductive armor tapes that are two crucial components in form-wound motor coils. The limitations of the conventional dc conductivity modeling and the necessities of using ac conductivity modeling and anisotropic properties of these materials at high frequencies and high electric field are discussed. The method of measurement of the dielectric parameters at high frequency and high electric field for 2D modeling is also presented. The transient FEM simulations from conventional modeling and the proposed ac modeling are compared to experimentally obtained results. Good agreement is only obtained from the latter modeling.