Conference Agenda

Thermocycling (TC) 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.

The IEEE 1310 standard, introduced in 2012, provides guidelines for thermal cycle testing of form-wound stator bars and coils in large rotating machines, emphasizing temperature uniformity across test samples. However, the standard specifies only one test assembly without accounting for alternative setups that may achieve similar or superior uniform temperature distributions. 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 presented in 2024 at the IEC conference, focusing on thermocycling (TC) tests for large turbo bars with 3-inch 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.

The health and safety of workers using chemical compounds (resins, paints and solvents) when installing, refurbishing or maintaining hydro generators is paramount. Recently observations have necessitated technological development to better achieve this goal. The uses of such chemical compounds include generator rewinds, painting of the stator winding and core, stator frame, rotor field poles, rotor mechanical assembly, etc. and the clean up when the work is ongoing and finally completed.

An analysis of the types of chemical compounds shows significant health and safety risks for workers such as Carcinogens, Mutagens and Reproductive (CMR). While Personal Protective Equipment (PPE) is reasonably effective in minimizing short time exposure, longer term exposure is still a concern. A new and preferred approach is the reformulation of the chemical compounds to eliminate the substances that pose risk. The authors of this paper have been working collaboratively to develop and qualify chemical compounds that eliminate these known health risks while still ensuring that the technical efficacy remains as good or better than the original.

While this work does not eliminate the need for PPE for site workers, the newly formulated and qualified chemical compounds eliminate the worst chronic risks for workers. The use of PPE to control more acute hazards such as eye, throat, and respiratory irritation will be maintained.

This paper will present the work done to qualify a family of products developed that eliminate the CMR risks. All chemical compounds presented will have been subject to laboratory and field testing with good overall technical performance that meets or exceeds the existing. Most important is solid feedback from personnel at site performing the work.

While this work presents new chemical compounds and technology, a list of currently qualified materials and their suggested applications will be provided so that users may start to take advantage thus reducing personnel risk at site.

It should be recognized that studies of the health affects of various chemical compounds continues, and as studies continue, new and further materials may be identified that have more extreme risks for workers. The materials currently presented are CMR free based on today’s technology, but overall, this type of work and mindset must continue into the future.