Power Limit Tests on Southeastern Power and Light Company´s System

The general subject of stability and power limits has been discussed several times before the Institute. Most of the papers have been of a theoretical nature, presenting methods by which the power limit of a system could be calculated, or describing various schemes by which the power limit could be increased. Some papers have been written describing tests on miniature systems and a few, giving the results of tests on actual high-voltage systems on the Pacific Coast. 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 and 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.