if the transformer converts 240v ac to 8V ac, ratio 30:1 then it should step up the voltage by the same ratio, i.e, 15V ac to 450v ac.but it's not the case !!
It must be using different terminals for step up and step down.
Ok firstly,you're going to need ALOT more than 80v if you plan to power a transformer. When in its transport form, be it a plane, car, lorry etc you can run it on ordinary diesel fuel, however in Robot form, In order to make it walk, your transformer would need far more power than a diesel engine could provide. Take Optimus Prime for example, the weight ratio of Prime, which would likely exceed 75 to 80 lbs per inch might be impossible to provide enough power to move your transformer on two legs. If you are well educated in hydraulic engineering, hydraulic power might allow your transformer to walk, but the hydraulic system itself would create a different lot of problems.The hydraulic pipes, along with your transformers fuel lines and electrical wiring, would have to remain undamaged or even untouched during transformation, and a secondary power source must be used to power the hydraulic pumps. In conclusion, If you're planning to power 35 to 40 tons of pure machine, good luck. Hope this helped.
