Vacuum Impregnation Plants Good insulation as well as protection from ambient conditions is vital for electrical equipment. Impregnation under vacuum using various resins and varnishes is the best solution for this purpose. Typical applications are electromagnetic coils, small transformers, instrument transformers, chokes, sintered bushes and similar products. For applications such as large motors and generators, high voltage transformers, special transformers, etc., it is required to apply pressure after impregnation.