Tesla's AC motor patents became a cornerstone of which Westinghouse-marketed AC system?

Tesla’s AC motor patents became a cornerstone of Westinghouse’s polyphase system. The system used alternating currents with different phase relationships to distribute power and create rotating magnetic fields in motors.

Tesla’s key breakthrough was the practical induction motor, which could run without a commutator and brushes. Its rotating magnetic field made it better suited to AC power networks than the high-maintenance DC motors then in common use. In 1888, George Westinghouse licensed Tesla’s motor and related transformer patents.

Westinghouse engineers later refined the technology and developed a workable commercial network. By the early 1890s, the company marketed the complete arrangement as the “Tesla Polyphase System.” At the 1893 World’s Columbian Exposition in Chicago, Westinghouse used polyphase AC to demonstrate reliable electric lighting and machinery.

Polyphase does not mean direct current, and it is not the same as a single-wire system. Modern three-phase power is the best-known example, although Tesla’s early Westinghouse motors commonly used two-phase designs.