Worked on the PyPSA/PyPSA repository to address a critical issue in transformer data handling by resolving a pandas dtype warning in the transformation pipeline. Focused on improving data consistency, the developer refactored transformer attribute assignments into a single operation and implemented explicit dtype casting to align with existing DataFrame types. This approach prevented potential type-mismatch errors and reduced runtime warnings, enhancing the reliability of downstream analyses and simulation reproducibility. Leveraging Python, Pandas, and refactoring skills, the work contributed to a more stable data flow within the project, supporting robust and maintainable data processing for power system analysis workflows.