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Project: T162700 #0143

Large turbine generators - whether steam or gas driven - are large, expensive, and complex machines. Utilities strive to maximize the reliability and availability of these assets while simultaneously ensuring that they are operated safely. These machines are designed to have economic lifetimes in the range of 20-50 years. Whether a generator is able to achieve this number of years of service is dependent on the operating environment and the timely application of maintenance. In addition, many large steam turbine generators currently operating may be at or close to end of life. Consequently, the role of maintenance engineers in utilities is becoming critical. In addition to these requirements, utilities are faced with some further challenges, namely –

‒ Increasing load cycling of the generators due to increased penetration of renewable energy sources and/or the demands of new grid codes imposed by transmission system operators

‒ An overall reduction in the industry (OEMs and utilities) of the training, skills, and experience required to safely and reliably operate large turbine generators and other power apparatus

Consequently, the objective of this guide was to provide less experienced or non-specialist engineers with the tools to –

‒ Understand the basic functions and composition of the major generator components (stator core, stator winding, and rotor winding), as well as important auxiliary systems

‒ Be aware of and be able to recognize the many failure mechanisms that may affect these systems during operation

‒ Provide some basic guidance on means of avoiding or repairing the effects of these failure mechanisms

‒ Know the many off- and on-line test techniques available to detect, at an early stage, the existence of deterioration mechanisms that may lead to failure, and their appropriate use

This document also includes a literature survey focused on the effects of flexible operation on major generator components and a survey of utilities to assess their awareness of and reactions to the challenges represented by load cycling and load shifting operation.


Generator, Stator, Core, Rotor, Auxiliary systems, Condition assessment, Diagnostic testing, Maintenance