The importance of grounding brushes to the safe operation of large turbine generators

Four sources of voltage on the shafts of large turbine generators are identified. Techniques for measuring these voltages are outlined. The consequences of not providing effective shaft-grounding brushes to reduce shaft potential, the magnitude of shaft potentials, and specific components which are at risk are discussed. Recommendations for basic installation and maintenance procedures for shaft-grounding brushes are made. Two unusual experiences attributed to grounding brushes are discussed