--- title: "Hydro generators: introduction to stator windings" date: 2019-10-01T13:47:00-04:00 author: jessica napert canonical_url: "https://www.bbaconsultants.com/en-ca/publications/hydro-generators-introduction-to-stator-windings" section: Publications --- 1. A variety of stator winding types (coil, bar and concentric) can be found in our hydropower generating units. The lifespan of a winding varies depending on the use, type of insulation (asphalt, polyester, epoxy, B-stage, VPI, etc.), quality of fabrication and installation, and maintenance. The stator winding is the part of hydropower generating equipment that has the highest operating costs due to equipment price, installation complexity, production loss and risk of unplanned breakage. With the loss of knowledge among most operators and the aging generating fleet, it is imperative to develop a maintenance strategy that incorporates specialized tests and regular inspections/assessments. Assessing the winding is key to its sound management and extending its remaining service life, its real purpose. Once the condition of the winding is known, there are different strategies available. The complete rewinding of the stator is the most obvious strategy, and it is also the one that requires the most effort and greatest investment. Other alternatives exist and may prove to be successful strategies for prolonging the winding’s remaining service life at a lower cost and for managing acceptable risk levels. This paper covers side packing, slot wedging, coil jumping, single bar replacement or neutral and phase inversion. We explore these topics both in this publication and in future articles. This content is for general information purposes only. All rights reserved ©BBA 1. ![François St-Germain](https://www.assets.bbaconsultants.com/bba-production-assets/production/images/avatars/_size_avatar/3188/Francois-St-Germain.webp) François St-Germain, P.Eng. Principal Engineer, Industrial and Hydro [ ](https://www.linkedin.com/in/fran%C3%A7ois-st-germain-785ba967/) - [ 27 Jul 2026 Mining and Metals Early tailings decisions shape long-term mine performance - ![Geraldine Cosset](https://www.assets.bbaconsultants.com/bba-production-assets/production/images/avatars/_size_avatar/206707/Geraldine-Cosset.webp) - ![Jared Purdy](https://www.assets.bbaconsultants.com/bba-production-assets/production/images/avatars/_size_avatar/212424/Jared-Purdy.webp) ](https://www.bbaconsultants.com/en-ca/insights/early-tailings-decisions-shape-long-term-mine-performance "Early tailings decisions shape long-term mine performance") - [ 02 Jul 2026 Mining and Metals Python: A key tool for data analysis in mineral processing - ![Charles Blais](https://www.assets.bbaconsultants.com/bba-production-assets/production/images/avatars/_size_avatar/211197/Charles-Blais.webp) - ![Juan Pablo Vergara](https://www.assets.bbaconsultants.com/bba-production-assets/production/images/avatars/_size_avatar/211266/Juan-Pablo-Vergara.webp) ](https://www.bbaconsultants.com/en-ca/insights/python-a-key-tool-for-data-analysis-in-mineral-processing "Python: A key tool for data analysis in mineral processing") - [ 19 Jun 2026 Mining and Metals Speed is earned early in projects - ![Mm employee men jean lheureux retouch web SQ LR BBA](https://www.assets.bbaconsultants.com/bba-production-assets/production/images/avatars/_size_avatar/204266/mm_employee_men_jean-lheureux_retouch_web_SQ_LR_BBA.webp) - ![Mm employee men benoit richard retouch web SQ LR BBA](https://www.assets.bbaconsultants.com/bba-production-assets/production/images/avatars/_size_avatar/203602/mm_employee_men_benoit-richard_retouch_web_SQ_LR_BBA.webp) ](https://www.bbaconsultants.com/en-ca/insights/speed-is-earned-early-in-projects "Speed is earned early in projects") - [ 17 Jun 2026 Industrial data platforms: building a solid foundation to optimize your operations - ![Pierre Boucher](https://www.assets.bbaconsultants.com/bba-production-assets/production/images/avatars/_size_avatar/2671/Pierre-Boucher.webp) Pierre Boucher, P.Eng. Senior Engineer, Operational Technology and Infrastructure ](https://www.bbaconsultants.com/en-ca/insights/industrial-data-platforms-building-a-solid-foundation-to-optimize-your-operations "Industrial data platforms: building a solid foundation to optimize your operations") [ See all ](https://www.bbaconsultants.com/en-ca/insights "Go to Publications listing page") Let’s see what we can do together [ Contact us ](https://www.bbaconsultants.com/en-ca/contact) 1. A variety of stator winding types (coil, bar and concentric) can be found in our hydropower generating units. The lifespan of a winding varies depending on the use, type of insulation (asphalt, polyester, epoxy, B-stage, VPI, etc.), quality of fabrication and installation, and maintenance. The stator winding is the part of hydropower generating equipment that has the highest operating costs due to equipment price, installation complexity, production loss and risk of unplanned breakage. With the loss of knowledge among most operators and the aging generating fleet, it is imperative to develop a maintenance strategy that incorporates specialized tests and regular inspections/assessments. Assessing the winding is key to its sound management and extending its remaining service life, its real purpose. Once the condition of the winding is known, there are different strategies available. The complete rewinding of the stator is the most obvious strategy, and it is also the one that requires the most effort and greatest investment. Other alternatives exist and may prove to be successful strategies for prolonging the winding’s remaining service life at a lower cost and for managing acceptable risk levels. This paper covers side packing, slot wedging, coil jumping, single bar replacement or neutral and phase inversion. We explore these topics both in this publication and in future articles. This content is for general information purposes only. All rights reserved ©BBA