Rotating electrical machines are embedded in nearly every sector of modern industry; they are widely used in industrial settings, as motors in transportation applications - including electric vehicles - and in power generation, where they are a key component of wind turbines.Technical advances are transforming what these machines can achieve. New developments in rotating electrical machinery have arisen from novel or improved materials, including new insulation materials, as well as advances in electrical steels and high-performance permanent magnets, and more rapid mass production techniques. These improvements deliver benefits such as cheaper and faster manufacturing and enhanced performance from the final products. At the same time, condition monitoring and maintenance techniques are also changing rapidly through increased application and further research and development, and are becoming essential to ensuring reliability, availability and cost-effectiveness for electrical machine systems, from small industrial drives to multi-megawatt generators.Condition Monitoring of Rotating Electrical Machines has established itself as a definitive reference for researchers and engineers in the energy, transport, process engineering and manufacturing industries and in related academic research. Coverage includes fundamental principles of condition monitoring, plus in-depth discussion of reliability, signal processing, online temperature, chemical and vibration monitoring, current, flux and power monitoring, partial discharge detection, drive monitoring, off-line monitoring, condition-based maintenance, use of AI and machine learning, and safety and training.This 4th Edition has been expanded, revised and updated throughout, and features new chapters, addressing novel machine designs, new materials, clean energy and transport, the use of AI, and strategies for reliability, availability and maintenance.