The first thing I think of is that there is something wrong with that older 3HP motor so you are not getting 3HP out of it.
The HP rating on electric motors mostly depends on heat. A motor can make some amount of power for some period of time before it gets too hot as long as you feed it enough electricity.
A motor that can make 10 HP continuously may well be able to make 100HP for 10 seconds from a cold start, the amps needed may be 15 times as much. |