The synchronous generators' excitation is usually regulated by means of a real-time digital control system, while other apparatuses are dedicated to secondary functions (e.g human machine interface, remote control unit, logic and control functions). A performance increase and a cost reduction can be achieved by integrating all the functions into a single platform. However, this requires assessing the dependability performance of the control systems currently in use, to set a base benchmark for future evaluations. In this paper, the quantitative dependability analysis of a digital excitation control system is performed, by using as a case study a real system installed in a hydroelectric power station. Two configurations are analyzed, and their dependability performance are compared.