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Edith Clarke: Early Pioneer of Grid Analysis

Published On
Jun 21, 2022

When it comes to developing smart grid technologies, the name Edith Clarke speaks volumes for the past and present.

Though born in 1883, when it was highly unlikely for women to become engineers, Clarke created something many electrical engineers throughout the world still consider a milestone invention.

An early pioneer of grid analysis, Clarke was granted a patent in 1925 for the Clarke Calculator. This graphical calculator consisted of a collection of diagrams and mathematical formulas intended to eliminate laborious computations to determine the characteristics of long electrical transmission lines and solve long-distance electrical power transmission problems.

As recently as 2019, IEEE Signal Processing Magazine published an article exploring the value of the Clarke Calculator in the context of today’s smart grid power networks. The authors were six engineering professors with degrees from or affiliated with Imperial College London. While they acknowledged the limitations of the calculator’s application in today’s world and described it as “designed from a circuit theory perspective and only for balanced ‘nominal’ system conditions,” they offered a modernized interpretation of its use. They also saluted Clarke’s legacy of developing mathematical formulas to solve power-related problems.

A sidebar tribute to Clarke accompanies their paper on power grid analysis. It states, “Recent progress toward the smart grid has only reinforced the importance of the Clarke transform as a platform for the wider involvement of signal processing and machine learning in numerous applications related to state estimation, frequency tracking, and fault detection.”

Orphaned at age 11, Clarke wisely used her inheritance to further her education. She graduated from Vassar College, having studied mathematics and astronomy, and was the first woman to earn a master’s from MIT. She was then the first woman in the United States to be professionally employed as an electrical engineer.

Early in her career, she directed a group of human computers for AT&T’s establishment of a transcontinental phone system. For General Electric (GE), she calculated mechanical stresses in high-speed turbine rotors. Her engineering work was incorporated into original turbine installations at Hoover Dam, which the American Society of Civil Engineers once considered one of this nation’s seven modern engineering wonders.

Clarke received additional patents related to electrical engineering and was the first woman to present a paper to the American Institute of Electrical Engineers. She also wrote a seminal textbook on power system losses and the performance of electrical equipment, “Circuit Analysis of A-C Power Systems,” published in 1943.

After retiring from GE, Clarke taught at the University of Texas at Austin for 10 years. She died in 1959. In 2015, she was posthumously inducted into the National Inventors Hall of Fame, which includes the likes of Thomas A. Edison, George Westinghouse Jr. and Nikola Tesla.

About the Author
Susan DeGrane

Susan DeGrane

Susan DeGrane is a Chicago-based freelance writer. She has covered electrical contracting, renewable energy, senior living and other industries with articles published in the Chicago Tribune, New York Times and trade publications. Reach her at sdegra...

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