The guidelines for online monitoring of large synchronous generators are described in this guide. High-level discussions of each of the proposed monitoring methods, and recommended threshold values, whenever there is a general agreement on those values, are included in this standard. Instrumentation that is clearly understood to belong to the protection scheme of the generator (e.g., differential protection) is not covered by this guide.

This document describes guidelines for online monitoring of large synchronous generators with ratings of 10 MVA and above. The scope includes generators with salient-pole rotors as well as generators with cylindrical rotors. This standard also provides basic information on the various online monitoring techniques described as well as recommended threshold values for initiating a remedial or compensating action, whenever those values are typical within the power generation industry. This standard does not cover those instruments that are clearly associated with the protection scheme of the generator, such as: differential, out-of-step, over/under frequency, and so forth.

The purpose of this guide is to a) Describe mechanisms of degradation and applicable monitoring devices. b) Describe methods available for online monitoring of large synchronous generators included within the scope of this standard. c) Recommend which of the online monitoring techniques described in this standard ought to be adopted based on machine type. d) Recommend monitored threshold values for initiating remedial or compensating actions when widely agreed industry practice exists.