John Forrest Kelly (March 28, 1859, in the vicinity of Carrick-on-Suir, Ireland – 1922) was an American electrical engineer who made early advances in alternating current equipment.
His first occupation was as assistant to Thomas A. Edison, in the Menlo Park laboratory, his work then principally relating to the chemistry of rare earths.
The art of building transformers and generators of alternating currents was revolutionized, and Mr. Kelly and his colleagues were the first to put polyphase motors into actual commercial service.
He was the first to make a hysteretically stable steel, a matter of vastly more importance than the comparatively spectacular transmission work.
He experimented in electrical transmission, distribution and measuring procedures and equipment: with Chesney and Stanley, he developed the SKC transformer.