Abridgment of an investigation of transmission-system power limits

Results of theoretical analysis, verified by miniature-system tests of the power limits of transmission systems, are discussed, among the major conclusions being the following: The criterion for stability under all conditions is the steady-state power limit. The charging kv-a. exercises marked detrimental effects on stability. The characteristics of synchronous terminal apparatus are of great importance. Improvements can be made by modifying present apparatus design. Automatic voltage regulators, suitable exciters, and fast relays are essential. The mercury-arc rectifier, as an adjunct in excitation circuits, shows real advantages.