Generator Stator Modernizations
Siemens offers comprehensive investigation and analysis of the generator stator to recommend the optimal course of action for your turbogenerator. We can modernize your stator with innovative and proven technology to significantly improve the long-term availability and reliability of your generator and therefore of your entire power plant. Further benefits can include the extension of scheduled maintenance intervals, shorter maintenance outage durations and lower maintenance costs. The following modernization measures can be performed by Siemens.
Our Stator Modernization Concepts in Detail
Stator Repair & Partial Refurbishment
With our localized in-situ refurbishment approach, repair of few strands up to multiple stator coil replacements can be performed. Furthermore, with an on-site stator core repair minor issues can be rectified. These repair and refurbishment methods are intended to reduce standstills after potential findings.
Fast Stator Rewind
As stator windings age, maintenance requirements or forced outages can increase until it becomes more economical to rewind than to constantly repair. Siemens is able to perform fast stator rewinds with all stator coil materials and insulation technologies.
Stator Core Replacement
As a generator stator ages, issues such as damage, hotspots or looseness are often identified. A complete or partial core replacement can help extend the generator’s lifetime and increase operating availability and reliability.
For specific generator types, Siemens can perform a Rapid Stator ReCore™. This process includes a new GVPI stator core, which is stacked and wound in factory and shipped to site. The original wound core is then removed, and the new wound core is installed. In the event of stator winding damage, a Rapid Stator ReCore™ replacement could be an economically attractive alternative to an on-site stator rewind.
Another option is to partially remove damaged stator core sections and restack with bonded lamination packs, called “Donuts”, on-site. This restacking can be performed with the frame either in vertical or horizontal position on the foundation.
If the replacement of the whole stator is required, Siemens can offer newly designed and manufactured generator stators. The old stator is removed from the foundation and replaced.
Newly designed and manufactured stators include updates and improvements such as advanced stator end winding designs with an improved vibration behavior as well as new stator coil designs to improve electrical, mechanical and thermal performance.
In case of urgently needed replacement stators due to e.g. a forced outage, Siemens could potentially support with a fast implementation of a spare stator if available.
Stator Slot Re-Wedge
The generator wedges are one of the main elements sustaining the tightness of the coils in the stator core slots. Maintaining a positive pressure on the stator coils reduces their movement within the slots, thus minimizing loss of semi conductive coating and wall insulation.
The Siemens procedure used for the stator rewedge was developed to provide high quality re-wedge. Siemens utilizes specially developed wedging tools to increase the efficiency of our procedure without impacting the generator core.
According to your generators configuration, further customized stator modernizations can be offered by Siemens.