Three-Phase Dump Loads in Hydropower Plants: The Story of a Poor Design

Hydroelectric power plants are typically equipped with spillways to drain excess water and regulate power production according to the load. However, these systems are not always available and alternative solutions must be adopted. A possible alternative to spillways is the use of a dump load consisting of a three-phase rheostat. The purpose of this paper is to present the history of a poorly designed refurbishment of a three-phase rheostat and to compare its performance with that of the old solution. Critical insights into the behavior of such devices are provided in order to avoid the same mistakes in the future.