Hi, lighthunter, first, thank you so mutch for your prompt response, i have 2 transformers transformers that i took from the APC UPS 3000. They have the same caractheristics, but i have one doubt, this UPS is 3000va, 48v battery bank imput - 220ac output, the primary has 4 wires, as you see in the photos, to test them i used a serial lamp, put the primary in serie, black-white + black-white. and the secundary also in serie, you can see the pictures, i have the 18v imput and 120 output, the only thing stranger, the serial lamp test, did not came off 100 per cent. What you think, can i go on or i'm going in a wrong way. thank you one more time. NJM