Synchronous machines, used in thermal, hydraulic and nuclear power plants, represent an essential part of the argentinian electrical system, being responsible of generating most of the energy that is supplied to the national grid. In this work, it is described a testing system oriented towards trying out generators control systems and protections, which is composed mainly of a real-time synchronous machine simulator and its multiplatform user interface. Hardware-in-the-loop simulations done with the developed simulator and a simple automatic voltage regulator are presented and their results are compared with computer simulations. Finally, some aspects on which it is possible to work in the future, in order to increase the capabilities of this simulator, are propounded.