Hello Colleague Antonioguanta. I have this simple, but complete transfer circuit for power plants with battery and starter: It is easy to modify it to suit your requirements: As indicated by the Greenmaster Colleague, for generators of less than 15 Kw, it is preferable to use selectors or blades, because the instability of the voltage and frequency that produce some loads of high consumption at start-up, can make contactors, timers and Reles failed. It is also possible to replace the contactor Ge1 and timer SA3 with 24V or 12V DC devices and supply them from a DC source so that the capacitor of said source avoids these possible intermittent faults in small generators. I am currently redesigning it with a Siemens brand logo, whose programming is extremely simple. Depending on my free time, I will probably be ready in 2 weeks. This is the selector or blade circuit: The power plant that I particularly use, is also a small generator (single phase) for consumption that I could have at home, for that reason I used a selector for 30 Amp contacts and instead of connecting it to the input wires of the brequera , in this case I connected it only to the 2-pitch output cables with lighting loads, fridge (refrigerator) and a few sockets with TV, computers and the like. Nor did I pass the neutral through the selector, that is, it does not comply with the standards, but in this personal case, it is of little importance to me, because here in Venezuela, the neutral is terrified from the residential distribution transformer and poles. This is the diagram I used: I hope I helped you. Luck. QRV