Nikola Tesla and Polyphase Power

The following text serves to outline the historical, theoretical, and practical development of the Tesla Four Phase System, from its inception to its initial commercial application at Niagara Falls. This also serves as an introduction to the video presentation.

Four Phase has not found the extent of application and theoretical development as has Three Phase. The application of Four Phase has been mainly confined to signal modulation and electrical servo systems. Its application to power systems is practically non-existent, with the exception of certain Poly-Phase rectifier systems in large radio transmitters.

Four Phase, however, offers certain advantages over Three Phase in electric power applications. A salient advantage is its "self replicating" character, which allows for four phases to be derived from two phases by simple polarity reversal, that is, one phase becomes another phase by reversing the winding of that one phase. Most important is the ease of transforming Four Phase Polyphase power into a pair of "Single Phase" power systems.

It is interesting to note that the conventional "wild phase" Delta connected power distribution system can convert to Four Phase with a very simple transformer connection. This is of great advantage when a Three Phase Polyphase system is required to power a load of an exclusively "Single Phase" character.