On this day in 1905 Andrew Gray was granted the patent for Circuit Breaker and Closers for Alternating Currents. U.S. Patent No. 792,020.
This inventions relates to circuit-closers for heaving alternating currents; and its object is to prevent sparking, which is done according to this invention by causing the current from the dynamo, whenever it is passing, to hold the contact-maker stationary, so that it can only be moved when the current is at zero between two alternations. For this purpose the contact-maker is carried by the armature of the electromagnet energized by a coil in the dynamo-circuit.