Pushing 800W of Wireless Power at 5 Meters

While testing a high-frequency transformer at our engineering lab in San Francisco last June, another transformer located across the lab began to smoke profusely, melting a grounding lead placed across its primary winding. Normally this might not be interesting, except that the transformer responsible for this misdeed was physically disconnected from any source of power. Unable to explain what had just happened, we set up a series of experiments to determine the cause.


Using the twin transformers in Figure 1 below, we discovered that the electric field between even widely spaced coils is quite capable of passing large amounts of power... without wires. Our test setup was able to wirelessly power 800 watts of light bulbs at a distance of 5 meters. By comparison the MIT/Intel wireless system using magnetic coupling is capable of 60 watts at 2 meters.