Clarke's early work focused on developing methods for analyzing long transmission lines, which are essential for the efficient and reliable distribution of electrical power over long distances. Her work considered line impedance, voltage drops, and power losses.

The Clarke Calculator was a groundbreaking tool that simplified the complex calculations involved in power system analysis. It used graphical methods to quickly determine the electrical characteristics of transmission lines.

Clarke made significant contributions to the application of the symmetrical components method in power system analysis. This method simplifies the analysis of unbalanced faults, which are common occurrences in electrical grids.

Clarke's textbook, 'Circuits Analysis of A-C Power Systems,' became a standard reference for electrical engineers. The book presented a comprehensive and accessible treatment of power system analysis, including the symmetrical components method.

The second volume of Clarke's textbook expanded on the concepts presented in Volume I, providing even more detailed coverage of power system analysis techniques. This further solidified her reputation as a leading expert in the field.