SYSTEM FOR MONITORING METAL-TO-METAL CONTACT IN ROTATING MACHINERY

摘要

16 A rub detector for rotating machines such as turbines wherein a grounding arrangement for the turbine rotor is monitored to detect coincidence between a rotor potential discharge and resulting current flow through the grounding arrangement. In the absence of such coincidence, a rub is suspect. In another arrangement in which a grounding strap is utilized, the strap is elevated from ground by means of a diode arrangement and the rotor voltage is monitored and compared with a predetermined reference which may not be exceeded. If the reference potential is attained by the rotor, then the rotor is discharged such that during cyclical operation, a certain discharge waveform is produced, and which waveform is modified in the presence of a rub condition. Means are also provided for imparting a potential to the rotor during initial start-up conditions.