Slot insulation is the common name for shielding material used for the rotor inside a power generator. The slot insulation process for electric motors provides a barrier between the copper wirings and the steel lamination for all stator, armature and rotor products.[1] This shielding material separates the rotor's electrically conductive winding from its body.[2]
Due to their operating environment, slot insulation must be capable of withstanding high temperatures. In the 1970s, slot insulation materials often had a Class F temperature rating (an operational range up to 155 °C).[3] Today, there are commercially available slot insulation materials with a Class H temperature rating (an operational range up to 180 °C)[4] Its composite of laminate materials, consisting of epoxy, aramid, and dielectric film, create its insulating properties.[5]