Optimization of Thermal Cycle Testing Setup of Bars of High-Voltage Turbo Generator

Thermal cycling (TC) test of the major windings elements: coils, and bars for High Voltage Rotating Machines (HVRM) became a highly employed test required to verify the reliability of the windings for these machines. IEEE Standard 1310–2012 provides thermal cycling guidelines for form-wound stator bars and coils in high-voltage rotating machines. It emphasizes temperature uniformity but prescribes only one test setup, without considering alternative configurations that may achieve equivalent or superior results. Our team has developed and tested a modified setup to improve temperature uniformity during TC tests, involving actual reassembly and reconnection of samples. This paper extends our prior research [2] [3], focusing on TC tests for large turbo bars with approximately 3 square inches (~1900 sq. mm.) copper cross-sections and 6 mm ground wall insulation thickness. These TC tests, critical for verifying the reliability of high-voltage rotating machines (HVRM) windings, are conducted to compare calculated and measured temperatures across various setups and cooling modes. This study explores an empirical and simulation-based approach, utilizing Finite Element Analysis (FEA) to identify optimal setups that predict uniform temperature distributions. This dual approach aims to reduce the need for physical sample reconfiguration and streamline the testing process. We propose that future revisions of IEEE 1310 prioritize temperature uniformity criteria, with setup guidelines relegated to the Annex to allow greater flexibility in achieving standardized results across the industry.