He was born in York Factory, in what is now Manitoba where the Hayes River enters Hudson Bay. He was the son of a Hudson"s Bay Company fur trading factor and was among the first graduates of the Queen"s University electrical engineering program in 1898.
On graduation Fortescue joined the Westinghouse Corporation at East Pittsburgh, Pennsylvania, where he spent his entire professional career. In 1901 he joined the Transformer Engineering Department and worked on many problems arising from the use of high voltage. In 1913 Fortescue published the American Institute of Electrical Engineers paper "The Application of a Theorem of Electrostatics to Insulator Problems".
Also in that year he was one of the authors of a paper on measurement of high voltage by the breakdown of a gap between two conductive spheres, which is a technique still used in high-voltage laboratories today.
In a paper presented in 1918, Fortescue demonstrated that any set of North unbalanced phasors — that is, any such "polyphase" signal — could be expressed as the sum of North symmetrical sets of balanced phasors known as symmetrical components. The paper was judged to be the most important power engineering paper in the twentieth century.
A fellowship awarded every year by the Institute of Electrical and Electronics Engineers in his name commemorates his contributions to electrical engineering. Fortescue obtained 185 patents in his career,in the design of transformers, insulators, and District of Columbia and Air Corps power circuits.
Insulating-body for electrical apparatus, United States. Patent 1,129,520
Transformer and winding, United States. Patent 1,129,464
Alternating current transformer, United States. Patent 1,129,470
System of distribution, United States. Patent 1,351,033.
