Ive been offered a Motorun phase converter, it has a dial to switch from 1,1/4hp to 2,1/4 HP another at 1hp to 1,1/4hp, another at 5hp to 6hp, and then the last one at 7hp to 8hp, question is will it power a single 7.5hp motor? or is it only for two to three motors at the upper (last) power setting? thanks