Economic application of powder resin based groundwall insulation for low voltage electric drives

Powder coating already forms an established variant of groundwall insulation although being used almost exclusively for small, flyer-wound rotors mostly due to the lack of economic application and curing processes for larger drives. However, insulation layers based on powder coatings are able to perform significantly better than common aramid-based slot liners. Regarding recent developments in powder application and curing, efficient application methods regarding energy consumption and process time are able to increase yield significantly. Regarding the altering topological characteristics of modern traction drives e.g. for electric vehicles, powder application and achievable results have to be investigated to assess the value of an industrial implementation. Experiments were performed using an electrostatic coating cell and a fixture simulating various characteristics of modern drives including inner diameter, slot width and -depth. These characteristics as well as available process values were analyzed towards the target figure coating thickness using DoE methods. Results predict a valid application of electrostatic powder coating within certain limits for larger traction drives. Package length should not exceed 80 mm and the diameter to package-length ratio has to be lower than 1.0 in order to achieve consistent, repeatable results. Electrostatic Powder Coating can be a valid alternative regarding groundwall insulation for traction drives, although the regarded process is expected to be best-suited for hybrid applications, due to large diameters and small package lengths of electric drives in this field.