Rotor-mounted scanners for hydroelectric generators

A distributed array of sensors mounted between poles on the rotor of an operating salient-pole hydrogenerator continuously provides the powerhouse control room with position-resolved, noncontact surveillance of both the stator core and the end turns. As the rotor spins, the sensors scan the stator for various symptoms of distress, including infrared, acoustic, and RFI (radio-frequency interference) emissions, which are sensitive indicators of hot spots, corona and/or partial discharges, and loose coils and/or wedges. The installation of the rotor-mounted scanner (RMS) greatly reduces the chances of forced outages resulting from catastrophic generator failure. As a diagnostic system, the RMS enables the utility to make realistic decisions relative to corrective actions, such as reducing machine load or scheduling a repair outage that has minimum impact on the economic dispatch of system generation. The RMS is described in detail along with a reliability verification.<>