Revision Standard - Active. Categorized in this guide are three direct-axis and four quadrature-axis models, along with the basic transient reactance model. Also discussed are some of the assumptions made in using various models. The fundamental equations and concepts involved in generator/system interfacing are presented. Covered, generally, are the various attributes of power system stability, recognizing two basic approaches. The first is categorized under large disturbance nonlinear analysis; the second approach considers small disturbances, where the corresponding dynamic equations are linearized. Applications of a range of generator models are discussed and treated. The manner in which generator saturation is treated in stability studies, both in the initialization process as well as during large or small disturbance stability analysis procedures is addressed. Saturation functions that are derived, whether from test data or by the methods, of finite elements are developed. Different saturation algorithms for calculating values of excitation and internal power angle depending upon generator terminal conditions are compared. The question of parameter determination or verification is covered. Two approaches in accounting for generator field and excitation system base quantities are identified. Conversion factors are given for transferring field parameters from one base to another for correct generator/excitation system interface modeling, Suggestions for modeling of negative field currents and other field circuit discontinuities are included.