Practices for Generator Synchronizing Systems (TR 121)

A synchronizing system that is designed and verified to operate within a generator's synchronizing limits is critical in helping maintain the life of generating plant assets and improving stability of the power system. There have been an increasing number of reported out-of-phase synchronizing events that have damaged generators and generator step-up transformers. This report presents the current practices for generator synchronizing systems. It includes an overview of synchronizing system components, their design considerations for different system and generating plant configurations, commissioning practices to verify that a synchronizing system will perform within limits, methods to monitor synchronizing system performance, and detect and alarm or trip for out-of-phase synchronizing events.