Abstract: An insulation system and method are disclosed for insulating formed coils of hydroelectric machines, such as a hydroelectric generator. The system includes strand/turn insulation that may include one or more layers of different materials, depending upon the dielectric requirements. A ground wall insulation is applied over the group of turns. The coil may be sized in a slot cell section. Additional insulation layers are provided, including a slot corona suppression insulation that extends just beyond stator slots, a voltage grading layer, and an armor layer. Time temperature profiles and preheating may be used to cure coil sections via press and heat. The resulting system is suitable for installation in situ, and affords superior resistance to degradation.