Oh, so many questions unanswered about the OPs needs. As well as the above regarding load sizes ... Does the 3P need to be 4 wire (ie with a neutral), of will 3 wire suffice ? Do the 3 phases need to be balanced (voltage wise) around the neutral ?
Provided a 3wire system is OK, then the simplest way of getting your 415V 3P supply is to use something like a
Transwave Converter. I have one of their static converters which I "acquired" when it was being thrown out at work some years ago. It's basically an auto-transformer to step up the 240V to 415V, together with a pile of large capacitors to generate a 3rd phase. There's a switch on the front to select the amount of capacitance (to suit different loads) and a voltage sensitive relay that switches in some more for starting the connected motor. It works very well.
They also do a rotary converter, which I believe is basically the same arrangement but using the windings of a 3 phase machine instead of a big transformer - ideally this needs a specially wound motor with one 415V winding tapped to inject 240V into it (dunno if this is what they have, their documents are vague on the internals). The advantage of a rotary converter is that the motor acts as a rotary transformer and evens up the balance of the phases - and indeed, you can connect a large 3 phase motor across the output to provide additional balancing.
A while ago we were experimenting at home using some of dad's "useful bits" he'd collected over the years. We'd got as far as a 5kVA transformer, an old manual star-delta starter, some capacitors, and a large (maybe 3-4 hp) 3 pahse with an old Ford Escort flywheel attached. It was working fine, but the transformer needed some adaptations - it needed some turns taking off the secondary as it wasn't the right turns ratio. Plan was to have a setup where running anything 3 phase would mean "switch on the power to the transformer, spin up the motor in star, switch to delta" which would then provide 3P to a separate distribution board.
Never went any further as my mate got divorced and lost the garage it was to go in, and the space where we'd got half way in assembling the 4t 4 poster lift it was to power, and last year most of the bits were in the loads I took to the scrapyard as "stuff I just couldn't keep due to lack of space" with dad gone and mum downsizing.
BTW - you may want to have a read of
Transwave's Layman's Guide.