Some commonly used models of induction motors may give erroneous results in bus transfer studies of auxiliary systems which contain induction motors driving low inertia loads.A thorough bus transfer study must consider three time periods: the disconnect period, the period immediately after reenergization, and the longer time period during which bus voltage and motor speeds are restored. This paper provides a report on a current investigation to determine if improved accuracy can be obtained using different induction motor models than presently being employed by the authors [1,2] for bus transfer simulations where the loads have low inertias.Bus transfer simulations are presented using five different models.Based on a comparison of these simulations, a motor model for each of the three time periods of interest is recommended.

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The ability to model the entire auxiliary system of large generating stations during emergency shutdown conditions aids the station designer in selecting the proper bus transfer scheme or schemes t o implement. The purpose of this paper is to provide one approach to developing such a model.The paper addresses representation of the power sources and the most popular types of transfer schemes. It also provides discussions on the major plant loads and their representations.Finally, results from the model presented are compared with an actual field test for reclosing an auxiliary bus in a fossil-fired generating station.

Approximately 15 years ago the Southern electric system (SES) launched an assessment program on bus transfer of station service loads in power generating stations during emergency shutdown. As a result of these activities, new bus transfer schemes were implemented on system units.The primary emphasis of this paper is to report on the initial assessment phase and to present the application philosophy developed for evaluating bus transfer performance. A brief overview of the types of transfer schemes available, the motivating factors and the criteria for transferring loads are given. Finally, the techniques for evaluating transfer performance and general results for a sample evaluation are presented.

Development and testing of emergency transfer of generating plant auxiliary system loads on the Southern electric system (SES) dates back approximately 15 years. Results of the bus transfer testingprogram have led to the refinement of automatic-supervised transfer schemes that allow for a safe and orderly shutdown in the event of a unit trip. The purpose of this paper is to present results from selected full scale tests and to demonstrate the value of a testing program. The discussion of each test will include a comparison of the actual test results with computer simulations.