Hydro Generator High Voltage Stator Windings: Part 4 – Type and Routine Production Testing

Abstract A rigorous program of type and routine testing is applied before and during the manufacturing of high voltage (HV) hydro generator stator windings. The purpose of type tests is to qualify the insulation system as suitable for its purpose, and the purpose of routine production testing is to ensure there are no manufacturing defects and deficiencies built into the coils during the manufacturing process. The testing for hydro generator windings is often specified by the purchaser, and quite commonly includes accelerated ageing tests. This paper outlines hydro generator winding type and routine production testing most commonly encountered in modern practice. The electrical tests carried out during and immediately after the winding installation are briefly covered at the end of this paper. The described tests apply equally to the resin rich coils and coils that are Vacuum Pressure Impregnated (VPI) in the coil shop before installation. Given the large physical sizes of hydro generators, globally processed VPI stators are rarely encountered and therefore not covered here.