Thermalastic Epoxy Insulation
The stator insulation system for our synchronous machines is Thermalastic Epoxy Insulation. This is a premium insulation system, developed by Westinghouse and proven in more than thirty years of outstanding performance on thousands of Westinghouse motors and generators. Thermalastic is under continuous development to maintain its position, as the worlds finest. The outstanding record of Thermalastic can be attributed to the fact that it is a mica-based insulation system. Mica has long been recognized as the most reliable insulating material due to its superior dielectric and voltage endurance capabilities.
Careful manufacturing procedures, including rigorous testing at critical points in the process, assure a distinctly superior insulation system. First, mica insulation is applied to the formwound stator coils. The coils are then installed in the slots and the completely wound stator is post-impregnated with epoxy resin in a vacuum pressure tank. Next, it is transferred to a baking oven for resin polymerization. The cycle is repeated for double protection. The result is a stator insulation system free of corona-generating voids, able to withstand prolonged voltage stresses, moisture, abrasion, dirt, thermal cycling, and frequent starting surges.
Various types of Thermalastic insulation are used depending on the physical size and voltage rating of the machines. On machines over 7000 volts, slot sections of the insulated coil are wrapped with a semi-conducting tape which, in conjunction with a corona-suppressing semi-conducting coating applied at the ends of the straight portion, protects the stator from corona damage. For very large diameter machines, Thermalastic insulation is applied to individual coils. Each coil is vacuum-pressure impregnated with solventless resin and cured before being wound into stator core slots. An additional resilient elastometric outer coating is available for applications in which the insulation is subjected to abrasive atmospheres. |
