Which Capacity Diesel Engine I Buy Kindly Suggest

That means 5 loads are on two phases while the third phase carries 6. So simple arithmetic means with no diversity 22.5kW x 6 x 3 phases = 405kW, giving 10% capacity increase for another 2 flats. However, diversifying the loads will reduce this demand by a factor that the forum cannot see.

Alternatively, if all loads are on one phase, then a generator of 22.5kW x 15 x 3 = 1MW+ is needed to support it with no spare capacity, with two phases doing nothing. However, diversifying the load will reduce this demand by a factor the forum cannot see.

but the current carrying in three phase supply is 2 times & in the case of single phase is 4.5 times.means 410 kw is 1815 amp for single phase. then from whom i can decide my diesel engine by kw or by amp.

Well, the starting point is how the load is distributed across the phases, about which the forum knows nothing.

How did you evaluate the load in each flat,did you consider diversity in each flat as well as overall diversity?.