Apparatus for monitoring phase currents and torsional vibrations of a

Abstract

Apparatus is described for monitoring phase currents and torsional vibrations of a turbine-generator which are indicative of the dynamic response of the machine during operation under load. The monitoring system disclosed includes probes which are operable to sense rotation of the main shaft of the turbine-generator and to feed the resulting signals to a vibration network. The vibration network eliminates from the signals any false components present at frequencies equal to multiples of the rate of rotation of the shaft and produces a composite vibration signal containing only true components of shaft torsional vibration. The composite vibration signal and a set of three phase current signals determined by stepping down, filtering, and amplifying the generator line currents are monitored continuously but recorded only when at least one of two signals derived from selected components of the composite vibration signal and phase current signals exceeds reference levels in an alarm system included in the monitor.