3Phase Genset Application

Rotary converters (mg sets) are quite efficient, maybe 97 percent:

http://www.northamericaphaseconverters.com/faq/

Most sets on the market are used to convert single phase to three phase, but there is no reason the opposite could not be done.

Probably a more common method these days is to rectify the 3 phase to DC, then drive a single phase inverter.

Lots of different approaches. Have you looked at these?

Let do some basic calculation. Assume the data as follows:

GENERATOR SINGLE PHASE Diesel (6000W) Specifications:-
Engine :10HP
Rated Watts :5500 watts
Surge Watts :6000 watts
Run Time : 8.5 hours at 50% load
AC Output :120V/240V

This is the single phase diesel engine generator specification

From the data above you need a 3 phase 10HP motor to run a 6000 watts generator which will give you approximate 25 ampere of current at 100% efficiency. But due to the generator losses the maximum current generated is only 22.9 Ampere.

The total power consumption will be 10HP x 0.764 = 7.64 kW. Therefore, for a month of electricity bill will be 7.64 x 24 x 30 days = 5,500.8kW multiply with your electrical charge per unit and you will get the total electrical bill per month.

The final electrical bill will be turn out to be higher than you though it is. Another factors is that your single phase generator will be running all the time at full speed even you don't use the electricity. Therefore, in this case the energy wastage from the single phase generator will be much-much higher than the power supply from the local utility.