Abridgment of power limit tests on Southeastern power and light company's system

Calculations and tests on small models have indicated that power systems at or near the theoretical power limit could not be operated safely, since any slight disturbance would cause instability with the resultant separation of the power transmission system. Very often, tests on small models do not closely check the results obtained on the real system; therefore, as a result of certain troubles which occurred on the Southeastern Power & Light Company's system in 1925, apparently due to instability, it was decided to attempt to determine by actual tests the amounts of power which could be safely carried over certain transmission lines, and to compare the results with the calculated values. The General Electric Company offered to cooperate with the engineers of the Southeastern Power & Light Company in conducting such tests, and made them of further value by suggesting experimentation with certain schemes of high-speed excitation which could be applied to the generator excitation systems, in an effort to increase the maximum power limit which could safely be carried over the transmission lines. This paper presents the results of these tests and the conclusions to be drawn from them.