generate questions: One of the things Tesla developed at that laboratory in 1887 was an induction motor that ran on alternating current, a power system format that was starting to be built in Europe and the United States because of its advantages in long-distance, high-voltage transmission. The motor used polyphase current which generated a rotating magnetic field to turn the motor (a principle Tesla claimed to have conceived in 1882). This innovative electric motor, patented in May 1888, was a simple self-starting design that did not need a commutator, thus avoiding sparking and the high maintenance of constantly servicing and replacing mechanical brushes.
What did Tesla develop in 1887? {sep_token} When was Tesla's innovative motor patented? {sep_token} What did Tesla's design not need? {sep_token} What did his design avoid in not having a commutator? {sep_token} what sort of design was this motor? {sep_token} When did Tesla make the induction motor? {sep_token} Why was AC electricity gaining popularity? {sep_token} What high maintenance part did Tesla's AC motor not require? {sep_token} When did Tesla patent the motor? {sep_token}