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Maxwell and Felici developed the theoretical basis of geometrical stress control during the period 1846 to 1862. The first practical implementation, however, was that of Nagel in Germany in 1906 (Figure 1). He developed the socalled Nagel-bushing on the basis of conductive layers . Around the same time, the Swiss professor Kuhlmann invented the refractive method . His aim was to decrease the electrical stress at the points where it was highest, rather than distributing it to other areas. The famous Rogowski profile was introduced in 1923. The basic principles are the same today, although the applications have become more complex, and stress control is still an important research area in HV engineering. Developments in stress control during the last 50 years (Figure 1) have been due mainly to new materials and production processes, and modern technologies, which have made possible to create cable accessories of more compact design and to improve their reliability. These developments have included impedance stress control based on heat-shrinkable tubing, and nonlinear stress control. In both cases the driving force was the need to improve the stress-control system of cable accessories.