The rational use of energy is a term very used at present, it�s a topic considered of general interest that presents innumerable laboral options and development of systems to achieve its aim. In the area of the electronic engineering the designs focus towards the efficient control of the energetic resources, application in lighting, vigilance of ignitions among other application. The current demand of energy, the enormous consumption of the energetic resource, among other factors, stimulate the development of technologies that help to realize a rational intelligent use of energy, an element very used at present by the companies is the use of the electronic instrumentation that controls and gives a suitable use of the energetic resources of the companies and homes.