C-5 Insulation
This inorganic-based surface insulation (equivalent to ASTM Type C-5 coating) is suggested for use where superior insulation is required after a stress-relief an- neal. It provides a uniform, high-resistance insulation for the more severe requirements of large electrical apparatus. C-5 insulation has a minimum effect on lami- nation factor. It can be exposed to ordinary stress-relief annealing temperatures without impairment of its superior insulation resistance when specified protective annealing atmospheres are used. In addition, C-5 insulation is not affected by oils, and provides some rust resistance. A small amount of organic material is contained in C-5 insulation to enhance die life relative to the standard surface finish and C-4 insulation. C-5 insu- lation is especially useful in large transformers made with stacked, flat laminations and in large motors and generators